Carbon is a chemical element with the symbol C and atomic number 6. It’s nonmetallic and tetravalent, which means it can form covalent chemical bonds with four electrons. It is in group 14 of the periodic table. Carbon accounts for only about 0.025% of the Earth’s crust. Carbon is the 15th most abundant element in the Earth’s crust and, by mass, the fourth most abundant element in the universe, following hydrogen, helium, and oxygen. Carbon’s abundance, the unique diversity of organic compounds, and unusual ability to form polymers at common Earth temperatures allow it to serve as a common element of all known life. After oxygen, it is the second most abundant element in the human body by mass (about 18.5 %).
Properties of Carbon
Some of the important properties of Carbon elements are listed below:
- Carbon generates four electrons in order to form a covalent bond.
- It exists in a variety of allotropes and other forms. Diamond and graphite are two examples of materials with distinct properties.
- Under normal conditions, carbon is extremely inert.
- This chemical element is denoted by the symbol C.
- It has the atomic number 6 because it has 6 protons in its nucleus.
- Carbon is nonmetallic as well as tetravalent.
- It comes in a variety of shapes.
- The chemical element can form bonds with other elements.
Application of Carbon
- It is a free element with numerous applications. These include using diamond or black pigment to decorate the rims of automobiles or printer ink.
- Graphite is another type of carbon that has been used in high-temperature crucibles, arc lamp electrodes, dry cells, and pencil tips.
- Another amorphous state of carbon is vegetal carbon, which is used as a bleaching agent and a gas absorbent.
- They use carbon dioxide and a fire extinguisher to carbonate drinks.
- Carbon in the solid form is known as dry ice.
- Carbon monoxide is also useful for the reduction in a variety of metallurgical processes.
- Carbon disulphide and carbon tetrachloride are two notable inclusions in industrial solvents.
Physical and Biological role of Carbon
Carbon is ranked 19th in the order of elemental abundance based on weight. It is estimated that the universe contains at least 3.5 times as many carbon atoms as silicon atoms. Except for carbon, only helium, oxygen, hydrogen, nitrogen, and neon are naturally abundant in the universe. When helium is burned, the cosmic product is carbon. Three helium nuclei with atomic weight 4 are fused in this process to produce a carbon nucleus with atomic weight 12.
Elemental carbon is a minor complement in the Earth’s crust. Carbon is widely distributed in the form of coal and organic compounds. They are made up of natural gas, petroleum, and plant and animal tissue. Carbon is an essential component of the photosynthesis process. It is a natural chemical reaction sequence that involves the conversion of the carbon cycle to form atmospheric carbon dioxide and carbohydrates.
Occurrence of Carbon
After hydrogen, helium, and oxygen, carbon is the fourth most abundant chemical element in the observable universe by mass. Carbon is abundant in the sun, stars, comets, and most planets’ atmospheres. Some meteorites contain microscopic diamonds that formed when the solar system was still in the form of a protoplanetary disc.
The great majority of carbonate rock masses contain carbon (limestone, dolomite, marble and so on). Coal is the most abundant commercial source of mineral carbon and is very rich in carbon (anthracite contains 92–98 %). The majority of diamond deposits are found in Africa. Diamonds are now being recovered from the seafloor off the coast of the Cape of Good Hope. Diamonds are found naturally, but approximately 30% of all industrial diamonds used in the United States are now manufactured.
Carbon can be found in the Earth’s atmosphere and is dissolved in all bodies of water. Carbon can also be found in hydrocarbons (such as coal, petroleum, and natural gas). Coal reserves are estimated to be around 900 gigatons. Carbon can also be found in methane hydrates found in the polar regions and beneath the seas.
It can also be found in the atmosphere as carbon dioxide, hydrocarbons as natural gas and petroleum, cellulose in wood, and limestone in combined states. Carbon compounds such as calcium and magnesium carbonates aid in the formation of common minerals such as dolomite, magnesite, limestone, and marble. Furthermore, the shells of clams, oysters, and corals are calcium carbonate.
Question 1: What is the composition of carbon?
Six neutrons and six protons make up carbon. It is a chemical element known for its ability to create patterns.
Question 2: Define carbon from the perspective of molecular formation
Carbon can form polymers, which are resilient, long chains of carbon linked with the same chemical element. Because of electron management, it can form bonds with four different atoms. A cloud of electrons surrounds the nucleus in which the atoms are arranged.
Question 3: Why does graphite conducts electricity, but not a diamond?
In the case of diamond, each carbon atom in a single crystal is covalently bound to four other carbon atoms, forming the four corners of a regular tetrahedron. There are no free electrons available due to the four covalent bonds with each carbon atom. Diamond is a poor conductor of electricity due to the lack of free electrons within its crystalline structure.
Every carbon atom in a single crystal of graphite is covalently bonded to three other carbon atoms. Due to the fact that each carbon atom has four valence electrons, one valence electron is left free for each carbon atom. By applying electric potential, these free electrons can be easily made to flow within the crystalline structure of graphite. As a result, graphite is an excellent electrical conductor.
Question 4: What are the physical properties of carbon compounds?
The physical properties of carbon compounds are as follows:
- Since they have covalent bonds between their atoms, they do not form ions. As a result, they are poor conductors of electrical current.
- These substances have low melting and boiling points.
- They are insoluble in water but soluble in organic solvents such as ether, carbon tetrachloride, and others.
Valence Electrons in Carbon
Carbon is a nonmetal in the periodic table’s group 14. Carbon, like the other elements in Group 14, has four valence electrons. The electrons in an atom’s outer energy level that are engaged in chemical bonds are known as valence electrons. The electron dot diagram in the Figure below depicts the valence electrons of carbon.
Carbon with four valence electrons
To fill its outer energy level, carbon requires four more valence electrons, for a total of eight valence electrons. The most stable arrangement of electrons is a whole outer energy level. Four covalent bonds can be formed by Carbon. Chemical bonds between nonmetals are known as covalent bonds. Two atoms share a pair of electrons in a covalent bond. Carbon shares four pairs of electrons by establishing four covalent bonds, thus filling its outer energy level and ensuring stability.
How Carbon Forms Covalent Bonds?
Gas is said to be a noble gas in nature if it has 8 electrons in its valence shell or two electrons in its valence shell in the case of Helium. Noble gases are also called inert gases or stable gases because they are stable in nature. Every atom tries to attain a noble gas configuration through bonding.
Noble Gases nearest to Carbon are Helium (He = 2) and Neon (Ne = 2, 8) are the inert gases nearest to carbon. Now, carbon has two choices to attain this configuration either by gaining four electrons (attaining Ne configuration) or by losing 4 electrons (attaining He configuration). But both of the choices with the Ionic Bond Formation are not feasible because:
- Formation of Carbon Anion by the gain of four electrons: By gaining four electrons, carbon becomes a C-4 Anion.
Anions are negatively charged ions formed when the atom has more electrons than protons. Here, Carbon has 6 protons and 10 electrons.
Although carbon attains Ne configuration it becomes difficult for the nucleus to hold ten electrons with six protons. So, it’s unstable and this bonding doesn’t take place.
- Formation of Carbon Cation by the loss of four electrons: By losing four electrons, carbon becomes C+4 Cation.
Cations are positively charged ions formed when the atom has more protons than electrons. Here, Carbon has 6 protons and 2 electrons
Although carbon attains He configuration it becomes difficult for the nucleus to hold two electrons with six protons. So, it’s unstable and this bonding doesn’t take place.
These two reasons don’t support the formation of Ionic Bonds in the case of Carbon. So, to its rescue Carbon completes its octet by sharing electrons and completing its octet. Such type of bonding where element completes their octet by sharing electrons is known to be Covalent in nature.
Thus, Carbon always forms Covalent Bonds.
Covalent bonds can be formed between carbon atoms or between carbon atoms and the atoms of other elements. Carbon and hydrogen frequently form bonds. Hydrocarbons are compounds that simply contain carbon and hydrogen. A hydrocarbon is something like methane (CH4), which is modelled in the diagram below. One carbon atom forms covalent connections with four hydrogen atoms in methane. All of the shared valence electrons are depicted on the left in the diagram below. Each pair of shared electrons is represented by a dash (–) in the figure on the right in the Figure below, which is called a structural formula.
Question 1: What are the atomic number and atomic configuration of Carbon?
Carbon possesses atomic number 6 and has configuration 2,4.
Question 2: Can carbon form Ionic Bonds? If yes, give example.
Carbon cannot form Ionic Bonds. It only forms Covalent bonds with other atoms.
Question 3: Define Covalent Bonding.
Bonding where there is no loss or gain of electrons and bond formation takes place by sharing electrons is called bonding having covalent nature or simply covalent bonding.
Question 4: Give examples of Carbon with Covalent bonds formation taking place.
CO2, CCL4, CH4 are all examples of Carbon making Covalent Bonds with other atoms.
Question 5: Explain the bond formation of CO2. What type of bonding takes place between the atoms of CO2? Diagrammatically explain its bond formation.
The nature of bonding between the atoms of CO2 is covalent in nature. Carbon and oxygen share electrons among them and there is no give or take of electrons. Carbon has 4 electrons in its valence shell shares its electrons with Oxygen having 6 electrons in its valence shell. In this way, there is sharing of electrons between atoms which takes place in CO2.
The diagrammatic representation of CO2 Bond formation is represented below:
Formation of CO2 by Covalent Bonding of Carbon with Oxygen
What are Allotropes?
Allotropy is the occurrence of an element existing in two or more forms with distinct physical qualities but similar chemical properties, and the different forms are known as allotropes.
Allotropes of Carbon
Allotropy is a phenomenon that occurs in carbon, and it appears in two sorts of allotropic forms:
- Carbon in crystalline allotropic forms: Carbon has four allotropes with well-defined crystal structures are,
- Carbon Nanotubes
- Carbon in amorphous allotropic forms: Amorphous allotropic forms of Carbon include:
- Wood charcoal
- Animal charcoal
- Sugar charcoal
- Gas Carbon
Diamond is a kind of carbon that has its atoms organised in a diamond cubic crystal structure. Another solid form of carbon known as graphite is the chemically stable form of carbon at normal temperature and pressure, although diamond nearly never transforms to it.
Diamond has the highest hardness and thermal conductivity of any natural substance, characteristics that make it ideal for cutting and polishing equipment in the industry.
Structure of Diamond
Jewel has a three-dimensional organization of carbon molecules combined through solid covalent bonds. Every Carbon iota is in the condition of sp3 hybridization and connected tetrahedrally to four adjoining Carbon molecules. This organization stretches out into three measurements. All Carbon-Carbon (C–C) bonds are equivalent and equivalent to 154 pm, and every C–C–C bond point is 109∘28′.
Structure of Diamond.
Properties of Diamond
- It is the most perfect and densest assortment of Carbon. Its thickness is 3.51 gcm–3.
- It is the hardest regular known substance and has an extremely high softening point (3843K) It is insoluble in all solvents.
- It is straightforward and measures a high refractive record.
- It is a terrible conveyor of power. This is on the grounds that all the valence electrons of every Carbon are engaged with the Carbon-Carbon Sigma (σ) bonds, and no unpaired electrons are left in the precious stone.
- Synthetically, jewel is impervious to practically all acids, antacids, and salts. In any case, it is followed up by melded Sodium Carbonate. When warmed with a combination of potassium dichromate and sulphuric corrosive to 475 K, it gradually gets oxidized to Carbon dioxide.
- The worth of a jewel relies on its size and shading. Pale blue-white jewels are more valuable than those having a low tone. Dark precious stones are the least expensive and not utilized in adornments.
Uses of Diamond
- Diamonds are used to cut glass cutters, marble saws, and rock drilling tools, among other things.
- Because of their exceptional brightness, diamonds are utilised in jewellery.
- Sharp-edged diamonds are used by eye surgeons to remove cataracts from the eyes with remarkable precision.
- Diamond dies are used to draw very thin metal wires such as tungsten.
Graphite: A Non-metallic Conductor
Each Carbon atom in graphite is in a state of sp2 hybridization, which means it is covalently linked to three other carbon atoms in the same plane. Planar hexagonal rings are produced as a result. The length of the Carbon-Carbon bond in this ring is 142pm.
Layers are formed by hexagonal rings. Van der Waal’s force holds the layers together, while 142pm separates them. Because these layers are able to slide over one another, graphite is soft and lubricious.
Properties of Graphite
- It has a metallic sheen and is dark grey in colour.
- Touching it feels extremely soft and oily.
- The fourth valence electron of each Carbon is free to travel since only three electrons of each Carbon are required to make hexagonal rings in graphite. As a result, graphite is a strong heat and electrical conductor.
- Dilute acids, alkalis, and chlorine do not harm it. It is slowly oxidised to carbon dioxide using a combination of potassium dichromate and sulphuric acid.
Uses of Graphite
- It’s used to make carbon arcs and electrodes.
- It’s a lubricant for equipment that operate at high temperatures.
- Lead pencils are made with this material. Graphite powder is combined with clay and formed into sticks. Pencils are made from these sticks.
- It is employed in atomic reactors as a moderator.
- It’s utilised in steel production as a reducing agent.
- It’s a component of high-strength composites.
- It’s utilised to make Crucibles, which can resist extremely high temperatures.
Buckminsterfullerenes: A Synthetic Allotrope of Carbon
Fullerenes are the main unadulterated type of Carbon since they don’t have astonishing edges or surface securities that draw in different iotas, as on account of graphite or jewel.
Fullerene is an enormous circular particle of arrangement C2n where n≥30. Fullerene is for all intents and purposes delivered by warming graphite in an electric bend in an inactive gas, for example, helium or argon when a dirty material is framed by the buildup of Cn little atoms.
The dingy material so shaped predominantly comprises of C60 with a more modest amount of C70 and hints of different fullerenes. The C60 and C70 Fullerenes can be promptly isolated from the fullerenes residue by extraction with benzene or toluene followed by chromatography over alumina.
Structure of C60 Fullerenes
Structure of fullerenes
In honour of American architect Robert Buckminster Fuller, the C60 fullerenes are sometimes known as Buckminsterfullerene or simply fullerene. Fullerene is a 60-vertices saucer-ball-shaped molecule having a Carbon atom at each vertex. It has 20 rings with six members and 12 rings with five members.
Six-membered rings can be fused to other six-membered rings as well as five-membered rings, whereas five-membered rings can only be fused to other six-membered rings. Single and double bonds with Carbon-Carbon lengths of 142pm and 138.3pm, respectively, are present.
Properties of Fullerene
- When the temperature is changed, the behaviour and structure of fullerene changes. The fullerene is transformed to the C70 form at a greater temperature.
- Under changing pressures, the structure of fullerene changes.
- Fullerene has an ionisation enthalpy of 7.61 electron volts.
- Fullerene has an electron affinity of 2.6 to 2.8 electron volts.
- In chemical processes, fullerene (C60) mimics an electrophile.
- Fullerene has the ability to behave as an electron acceptor. It can readily receive three or more electrons. As a result, it has the potential to act as an oxidising agent.
- To achieve superconductivity, fullerenes are doped with alkali or alkaline earth metals.
- Fullerene has the property of ferromagnetism.
- Fullerene is abundant in carbon compounds. It’s extremely soluble in organic solvents as a result of this.
Use of Fullerene
- Conductors made of fullerene are utilised.
- It has the ability to absorb gases.
- Lubricants made of fullerene are utilised.
- Fullerenes are utilised in the manufacture of cosmetics-related products in several forms.
- Graphene sheets make up carbon nanotubes.
- Fullerenes are utilised in biological applications in some ways.
Question 1: What is the purest form of Carbon?
Because it lacks the glittering edges and surface bonds that attract other atoms seen in graphite and diamond, fullerene is the cleanest form of carbon.
Question 2: How is fullerene obtained?
When graphite is heated in an electric arc in an inert atmosphere such as helium or argon, a sooty substance is produced by the condensation of Cn tiny molecules, resulting in fullerene. Extraction with benzene or toluene followed by chromatography over alumina separates the C60 and C70 fullerenes found in sooty material from the fullerenes soot.
Question 3: What are the uses of Graphite?
1) It’s used to make carbon arcs and electrodes.
2) It’s a lubricant for equipment that operate at high temperatures.
3) Lead pencils are made with this material. Graphite powder is combined with clay and formed into sticks. Pencils are made from these sticks.
4) It is employed in atomic reactors as a moderator.
5) It’s utilised in steel production as a reducing agent.
6) It’s a component of high-strength composites.
7) It’s utilised to make Crucibles, which can resist extremely high temperatures.
Question 4: How does carbon form a bond with other atoms?
Carbon has an atomic number of 6, which indicates that the electronic configuration of the carbon atom is 2,4. Because a carbon atom’s outermost shell has four electrons, it shares those electrons and reaches the inert gas state. As a result, the carbon atom creates covalent connections with other atoms.
Question 5: What are the uses of Diamond?
- Diamonds are used to cut glass cutters, marble saws, and rock drilling tools, among other things.
- Because of their exceptional brightness, diamonds are utilised in jewellery.
- Sharp-edged diamonds are used by eye surgeons to remove cataracts from the eyes with remarkable precision.
- Diamond dies are used to draw very thin metal wires such as tungsten.
All living organisms, such as plants and animals, contain organic compounds. All organic compounds were originally derived from natural minerals obtained from living things. As a result, it was assumed that organic compounds could only be generated within a living body (plant or animal body) and that the preparation required a ‘vital force’ that creates living things.
In 1828, a scientist named Friedrich Wohler disproved this vital force theory of organic compounds. Urea is an organic compound that was previously assumed to be formed only inside the bodies of living beings such as animals. In the laboratory,
Friedrich Wohler synthesized the organic compound urea [CO(NO2)2] from the inorganic compound ‘ammonium cyanate’ (NH4CNO). As a result, the vital force theory for the synthesis of organic compounds was rejected.
Why organic compounds are generally Covalent?
The organic compounds have low melting points and low boiling points. Organic compounds (or carbon compounds) have low melting and boiling points, indicating that the forces of attraction between their molecules are weak. They are, therefore, covalent compounds. Furthermore, most organic compounds are non-conductors of electricity, which indicates they do not contain ions. This also shows that organic compounds are naturally covalent.
Existence of a Large number of Organic compounds
There are more than 5 million organic compounds recognized at this time. Every day, scientists prepare a large number of new organic compounds. The number of organic compounds outnumbers the total number of compounds made up of all other elements.
The two properties of carbon elements that lead to the formation of a large number of organic compounds are catenation and tetravalency that are discussed further below:
The ability of carbon atoms to join with one another via covalent bonds to form long chains or rings of carbon atoms is one reason for the existence of a large number of organic compounds or carbon compounds. Carbon has an unusual property since it can form the longest chains with its atoms.
Catenation is the property of the carbon element that allows its atoms to link together to form long carbon chains. We term a property catenation when an element forms bonds between its atoms to form large molecules. Self-linking is another term for catenation.
For example- In molecules like some proteins, carbon may form the longest chains, containing millions of carbon atoms. Catenation is a chemical bonding that occurs only between atoms of the same element that have a valence of at least two and create relatively strong bonds with each other.
This property is prevalent among carbon atoms, notable among sulphur and silicon atoms, and slightly present among germanium, nitrogen atoms. As a result, a large number of organic compounds are due to the property of catenation of carbon elements. Three types of chains can be formed when carbon atoms combine. As shown below, there are three types of chains: straight chains branched chains, and closed chains or ring type chains.
Various carbon chains
The carbon atom has a total of 6 electrons because its atomic number is 6. Its electronic configuration can be written as 2,4. It means the outermost shell has four electrons. To achieve a stable electronic configuration, carbon requires four electrons to achieve the inert gas configuration. So carbon follows the octet rule and makes four covalent bonds with other atoms. As a result, carbon is tetravalent, meaning it has a valency of four and can create four covalent bonds with not just carbon atoms but also with other atoms. This is referred to as carbon tetravalency.
Carbon has the remarkable property of forming extremely strong covalent bonds, making carbon molecules extremely stable. Another reason for the abundance of organic compounds or carbon compounds is that carbon has a valency of four, which is relatively big. Because of its large valency of 4, a carbon atom can make covalent bonds with numerous other atoms, including hydrogen, oxygen, nitrogen, sulphur, and many others. As a result, a large number of compounds are formed.
Question 1: Name some elements that exhibit catenation property.
Catenation is a property when an element forms bonds between its own atoms to form large molecules. Carbon, sulphur, and silicon exhibit the property of catenation.
Question 2: Why does carbon mostly form compounds by covalent bonds?
Most carbon compounds are non-conductors of electricity, which indicates they do not contain ions. Therefore, carbon forms compound mainly by covalent bonds.
Question 3: What are carbon-hydrogen compounds called?
The name of carbon-hydrogen compounds is hydrocarbons.
Question 4: How was the vital force theory for the synthesis of organic compounds rejected?
It was assumed that organic compounds could only be generated within a living body and the preparation required a vital force. When Friedrich Wohler synthesised the organic compound urea from the inorganic compound ammonium cyanate, the vital force theory for organic compound synthesis was rejected.
Question 5: Why do organic compounds have relatively low melting and boiling points?
Individual molecules are held together by covalent bonds in organic compounds. Molecules are attracted to each other by relatively weak forces. Since the attraction forces between molecules are weak, it takes little energy to disrupt them, resulting in low melting and boiling points for organic compounds.
Naming of Hydrocarbons
The International Union of Pure and Applied Chemistry (IUPAC) established the official names or systematic names of organic compounds in 1958, and they are known as IUPAC names or IUPAC nomenclature. The following points should be kept in mind while using the IUPAC method to name hydrocarbons.
- The number of carbon atoms in a hydrocarbon is represented by the stem below.
|One carbon atom||Meth|
|Two carbon atoms||Eth|
|Three carbon atoms||Prop|
|Four carbon atoms||But|
|Five carbon atoms||Pent|
|Six carbon atoms||Hex|
|Seven carbon atoms||Hept|
|Eight carbon atoms||Oct|
|Nine carbon atoms||Non|
|Ten carbon atoms||Dec|
- The term ‘ane’ is written after the stem to denote a saturated hydrocarbon with single bonds.
- The term ‘ene’ is written after the stem to denote an unsaturated hydrocarbon with double bonds.
- The word ‘yne’ is written after the stem to denote an unsaturated hydrocarbon with triple bonds.
Naming of Saturated Hydrocarbons
- The naming of CH4– This chemical has one carbon atom, which is denoted by ‘meth’. It’s saturated since it’s made up entirely of single bonds. The ‘ane’ at the end denotes a saturated hydrocarbon. When the ‘meth’ and ‘ane’ are combined, the IUPAC nomenclature for this substance is ‘methane’ (meth+ane=methane). Methane is the IUPAC name as well as the common name for the hydrocarbon CH4.
Structure of Methane CH4
- The naming of C2H6– The letter ‘eth’ denotes the presence of two carbon atoms in this molecule. It’s saturated since it’s made up entirely of single bonds. The ‘ane’ at the end denotes a saturated hydrocarbon. When ‘eth’ and ‘ane’ are combined, the IUPAC name for this combination is ‘ethane’ (eth+ane=ethane). The IUPAC and common names for the hydrocarbon C2H6 are identical, ethane.
Structure of Ethane C2H6
IUPAC Nomenclature for Branched-Chain Saturated Hydrocarbons
The following rules should be kept in mind when using the IUPAC technique to name saturated hydrocarbons with branching chains.
- In the structure of the compound to be named, the longest chain of carbon atoms is located first. The compound is then classified as a derivative of the alkane hydrocarbon, which is the carbon atom chain with the largest length. This is referred to as “parent hydrocarbon.”
- The alkyl groups found as side chains (branches) are referred to as substituents and are denoted as methyl (CH3-) and ethyl (C2H5-) respectively.
- The longest carbon chain’s carbon atoms are numbered in such a way that the alkyl groups (substituents) receive the lowest possible number.
- The number of the carbon atom to which the alkyl group is attached is used to denote its position.
- Writing the ‘position and name of alkyl group’ exactly before the name of the ‘parent hydrocarbon’ yields the IUPAC name of the compound.
Naming of Unsaturated Hydrocarbons with Double Bond
- The naming of C2H4– The letter ‘eth’ denotes the existence of two carbon atoms in this molecule. This hydrocarbon is unsaturated because it has a carbon-carbon double bond. The ‘ene’ at the ending is used to denote a double bond. When the letters ‘eth’ and ‘ene’ are combined, the IUPAC name for this combination is ‘ethene’ (eth+ene=ethene). Ethene has a common name known as ethylene.
Structure of ethene C2H4
- The naming of C3H6– The letter ‘prop’ denotes the presence of three carbon atoms in this molecule. This hydrocarbon is unsaturated because it has a carbon-carbon double bond. The ‘ene’ at the ending is used to denote a double bond. When the letters ‘prop’ and ‘ene’ are combined, the IUPAC nomenclature for this combination is ‘propene’ (prop+ene=propene). Propane has a common name known as propylene.
Structure of Propene, C3H6
Naming of Unsaturated Hydrocarbons with Triple Bond
- The naming of C2H2– The letter ‘eth’ denotes the presence of two carbon atoms in this molecule. This hydrocarbon is unsaturated because it has a carbon-carbon triple bond. The ‘yne’ at the ending is used to denote a triple bond. When the letters ‘eth’ and ‘yne’ are combined, the IUPAC name for this combination is ‘ethyne’ (eth+yne=ethyne). Acetylene is the common term for ethyne.
Structure of ethyne, C2H2
- The naming of C3H4– The letter ‘prop’ denotes the presence of three carbon atoms in this molecule. This hydrocarbon is unsaturated because it has a carbon-carbon triple bond. The ‘yne’ at the ending is used to denote a triple bond. When the letters ‘prop’ and ‘yne’ are combined, the IUPAC nomenclature for this combination is ‘propyne’ (prop+yne=propyne). Propyne has a common name known as methyl-acetylene.
Structure of Propyne, C3H4
What are Isomers?
A molecular formula represents only one substance in inorganic chemistry. For example, HSO stands for sulphuric acid, which is a single compound. However, in organic chemistry, a single molecular formula can be used to represent two or more distinct molecules. This is because the identical carbon atoms in organic molecules can be arranged in a variety of ways to produce distinct structures and thus different compounds. In organic chemistry, for example, the same chemical formula C4H10 can represent two different compounds: normal-butane and iso-butane. The following example will help to clarify this topic.
- Consider the chemical molecule butane (C4H10). This chemical has four carbon atoms that can be linked in two ways to create two different structures. To begin, all four carbon atoms are connected in a continuous straight chain to form the structure seen below. The compound normal butane, abbreviated as n-butane, is represented by this structure.
- In the second case, three carbon atoms can be combined in a straight chain and the fourth carbon atom can be joined in a side chain, resulting in the structure illustrated below. Iso-butane is the chemical that has this structure.
Although n-butane and iso-butane have the same chemical formula (C4H10), their structures are distinct. They’re known as isomers. Isomers are chemical molecules with the same molecular formula but distinct structures. In other words, isomers are organic molecules that have the same chemical formula but differ in their carbon atom configurations. Isomers include normal butane and isobutane, which have the same chemical formula but distinct structures or arrangements of carbon atoms. Iso-butane has a branched-chain structure, whereas normal butane has a straight-chain structure. It’s also worth noting that the IUPAC names for n-butane and iso-butane are 2-methylpropane or simply methyl propane.
Isomerism refers to the existence of two or more distinct chemical molecules with the same molecular formula but different structures. Only hydrocarbons with four or more carbon atoms can have two or more distinct configurations of carbon atoms, making isomerism possible. Since only one arrangement of carbon atoms is allowed in hydrocarbons with 1, 2, or 3 carbon atoms per molecule, no isomerism is possible.
For example, no isomerism is possible in methane, ethane, or propane since they contain only one, two, or three carbon atoms, respectively, and various configurations of carbon atoms are not possible with only 1, 2, or 3 carbon atoms. The chemical butane (C4H10) can have two isomers. Butane’s two isomers have already been discussed. There are three isomers of the chemical pentane (C5H12), and five isomers of the compound hexane (C6H14). The number of potential isomers increases rapidly as the number of carbon atoms in an alkane molecule increases.
What are Homologous Series?
In the same way that all elements with similar electron structures have similar chemical properties and are grouped together in the same periodic table group, all organic compounds with similar structures have similar properties and are grouped together in the same group or series. The organic compounds are then organized in increasing molecular mass order.
A homologous series is a collection of organic compounds with identical structures and chemical characteristics that differ only in the CH2 group between them. Homologous refers to the different chemical molecules that make up a homologous series. The two neighbouring molecules are clearly separated by one carbon atom and two hydrogen atoms (or CH2 group).
Homologous Series of alkanes- Since all alkanes have identical structures with single covalent bonds and chemical characteristics, they can be classified together in a homologous series. The first five alkanes in the homologous series are listed below.
The homologous series of alkanes have the general formula CnH2n+2, where n is the number of carbon atoms in one molecule of alkane. One carbon atom makes up the first member of the alkane series. The second alkane series member has two carbon atoms. The third alkane series member has three carbon atoms. The fourth alkane series member has four carbon atoms, while the fifth alkane series member has five carbon atoms.
Homologous Series of alkenes- The homologous series of alkenes has the general formula CnH2n, where n is the number of carbon atoms in one molecule of alkene. The first five alkenes in the homologous series are listed below.
The alkene series begins with the first member, which has two carbon atoms. The second member of the alkene series has three carbon atoms. The third member of the alkene series has four carbon atoms. The fourth members of the alkene series have 5 carbon atoms, whereas the fifth member has 6 carbon atoms.
Homologous Series of alkynes– The homologous series of alkynes has the general formula CnH2n-2, where n is the number of carbon atoms in one molecule of alkyne. The first five alkynes in the homologous sequence are listed below.
The alkyne series begins with the first member, which has two carbon atoms. The second member of the alkyne series has three carbon atoms. The third member of the alkyne series has four carbon atoms. The fourth member of the alkyne series each has 5 carbon atoms, whereas the fifth member has 6 carbon atoms.
Characteristic of Homologous Series
The following are the properties of the Homologous Series.
- The chemical characteristics of all substances in a homologous series are similar. All alkane series molecules, such as methane, ethane, propane, and others, undergo substitution reactions with chlorine.
- A homologous series’ members can all be represented by the same general formula.
- In their molecular formulas, any two neighbouring homologous differ by one carbon atom and two hydrogen atoms.
- With increasing molecular mass, members of a homologous series display a steady change in their physical properties.
- Any two neighbouring homologous molecules have a molecular mass difference of 14u.
Question 1: Are the isomers of C3H8 possible?
For the given compound C3H8, there are 3 carbon atoms. Since only one arrangement of carbon atoms is allowed in hydrocarbon with three carbon atoms, so no isomerism is possible. Hence the isomers of C3H8 are not possible.
Question 2: The given compounds, C3H8, C4H10 are the neighbouring compounds of the same homologous series or not?
The two neighboring compounds of the same homologous series are separated by one carbon atom and two hydrogen atoms. Since the given compounds differ by one carbon atom and two hydrogen atoms, i.e. CH2 group. So these compounds are the neighbouring compounds of the same homologous series.
Question 3: The name of the hydrocarbon CH2=CH2 is ethane or not?
In the given compound, there are two carbon atoms, so ‘eth’ denotes the existence of two carbon atoms. There is a double bond between carbon carbon atoms, which is indicated by ‘ene’ at the end. So, the name of the given compound should be ethene. But at the end of given name ‘ethane’ there is ‘ane’ which indicated a single bond. Hence ethane is not the name of CH2=CH2.
Question 4: Name a hydrocarbon other than pentane, which has more than three isomers.
A hydrocarbon, which has more than three isomers is hexane, C6H14.
Question 5: An alkene has 34 carbon atoms in its molecule. How many hydrogen atom does this molecule have?
The general formula CnH2n, where n is the number of carbon atoms in one molecule of alkene. Since it is given that there are 34 carbon atoms, so n=34. Putting the value of n in the above formula,we get C34H2(34), or C34H68. So there are 68 hydrogen atoms in this molecule.
Types of Hydrocarbons: Hydrocarbons are of two types which are saturated hydrocarbons and unsaturated hydrocarbons.
A saturated hydrocarbon is one in which all of the carbon atoms are connected by a single bond. Saturated hydrocarbons are also called alkanes.
An alkane is a hydrocarbon in which the carbon atoms are only connected together by a single covalent bond. In an alkane, there are no double or triple bonds. As a result, the hydrocarbons methane, ethane, propane, and butane form a series of compounds known as alkanes. All of these saturated hydrocarbons have ‘ane’ at the end of their names.
The general formula of saturated hydrocarbons or alkanes is CnH2n+2 where n is the number of carbon atoms in one molecule of the alkane.
- If an alkane has 1 carbon atom in its molecules, then n= 1, and its molecular formula will be C1H2(1)+2 or CH4.
- If an alkane has 2 carbon atoms in its molecule, then n= 2, and its molecular formula will be C2H2(2)+2 or C2H6.
- If an alkane has 3 carbon atoms in its molecule, then n= 3, and its molecular formula will be C3H2(3)+2 or C3H8.
- If an alkane has 4 carbon atoms in its molecule, then n= 4, and its molecular formula will be C4H2(4)+2 or C4H10.
Methane (CH4), ethane (C2H6), propane (C3H8), and butane (C4H10), are all saturated hydrocarbons which contain only carbon-carbon single bonds are shown below.
Structural formulae of some alkanes.
An unsaturated hydrocarbon is one in which two carbon atoms are connected by a double bond or triple bond. Two important unsaturated hydrocarbons are ethene (C2H4) and ethyne (C2H2) because ethyne contains a triple bond and ethene contains a double bond between the two carbon atoms.
A double bond is formed by sharing two pairs of electrons between two carbon atoms whereas, a triple bond is formed by sharing three pairs of electrons between two carbon atoms.
Unsaturated hydrocarbons are typically obtained from petroleum through a process known as cracking. Unsaturated hydrocarbons are of two types,
- those containing carbon-carbon double bonds called alkenes and
- those containing carbon-carbon triple bonds called alkynes.
An alkene is an unsaturated hydrocarbon with two carbon atoms connected together by a double bond. Alkenes have a double bond between two carbon atoms that are formed by sharing two pairs of electrons, resulting in a total of four electrons.
Since they have a double bond between two carbon atoms, ethene (CH) and propene (CH) are alkenes. Since an alkene has a double bond between two carbon atoms, the molecule of the most simple alkene will have two carbon atoms. There can not be only a single carbon atom in an alkene. Alkene has the general formula CnH2n where n is the number of carbon atoms in one molecule of the alkene.
- If an alkene has 2 carbon atoms in its molecules, then n= 2, and its molecular formula will be C2H2(2) or C2H4.
- If an alkene has 3 carbon atoms in its molecule, then n= 3, and its molecular formula will be C3H2(3) or C3H6.
- If an alkene has 4 carbon atoms in its molecule, then n= 4, and its molecular formula will be C4H2(4) or C4H8.
An alkyne is an unsaturated hydrocarbon with two carbon atoms connected together by a triple bond. Alkynes have a triple bond between two carbon atoms that are formed by sharing three pairs of electrons, resulting in a total of six electrons.
Since they have a triple bond between two carbon atoms, ethyne and propyne are alkynes. Since an alkyne has a triple bond between two carbon atoms, the molecule of the most simple alkyne will have two carbon atoms. There can not be only a single carbon atom in an alkyne. Alkyne has the general formula CnH2n-2 where n is the number of carbon atoms in one molecule of the alkyne.
- If an alkyne has 2 carbon atoms in its molecules, then n= 2, and its molecular formula will be C2H2(2)-2 or C2H2.
- If an alkyne has 3 carbon atoms in its molecules, then n= 3, and its molecular formula will be C3H2(3)-2 or C3H4.
- If an alkyne has 4 carbon atoms in its molecules, then n= 4, and its molecular formula will be C4H2(4)-2 or C4H6.
The simplest alkene is ethene and the simplest alkyne is ethyne.
Structural formulae of ethene and ethyne.
Question 1: Mention an important difference between a saturated hydrocarbon and an unsaturated hydrocarbon.
Saturated hydrocarbons have only single bonds and are unreactive whereas unsaturated hydrocarbons have double or triple bonds and are quite reactive.
Question 2: How many carbon atoms does the simplest alkene have?
An alkene has a double bond between two carbon atoms, so a simplest alkene will have two carbon atoms.
Question 3: Mention an important difference between an alkane and alkene.
An alkane has carbon-carbon single bonds only and an alkene has carbon-carbon double bonds only.
Question 4: Identify if the given compound C3H4 is an alkene or alkyne.
The alkenes have carbon-carbon double bonds and their general formula is CnH2n. The alkynes have carbon-carbon triple bonds and their general formula is CnH2n-2. Here in the given compound n= 3. Now put n= 3 in the general formula of alkene, we get C3H2(3) i.e., C3H6 which does not match the given compound, so it is not alkene. Now put n= 3 in the general formula of alkyne, we get C3H2(3)-2 i.e., C3H4 which is the given compound. So the given compound is an alkyne.
Question 5: Write the molecular formula of alkane, if the hydrocarbon molecule has 3 carbon atoms.
The general formula of alkane is CnH2n+2 where n is the number of carbon atoms in a molecule. Given that there are 3 carbon atoms in the given hydrocarbon, so n= 3. Now put n= 3 in the general formula of alkane, we get C3H2(3)+2 i.e., C3H8. So the molecular formula of alkane having 3 carbon atoms is C3H8.
What are Functional Groups?
A functional group is an atom or a group of atoms that makes a carbon compound or an organic compound reactive and determines its properties.
Functional groups are atoms within molecules that have distinct properties regardless of the other atoms in the molecule. In organic chemistry, functional groups are the substituent atoms or groups of atoms that are connected to certain molecules. The halo group, alcohol group, aldehyde group, ketone group, carboxylic acid group, alkene group, alkyne group, etc. are some of the most important functional groups in organic chemistry.
List of Functional Groups
All the useful functional groups can be listed as follows:
- Halo (Alkyl Halide) Group
- Alcohol Group
- Aldehyde Group
- Ketone Group
- Carboxylic Acid Group
- Alkene Group is a carbon-carbon double bond. The compounds containing the alkene group are known as alkenes. The homologous series of alkenes have the general formula CnH2n, where n is the number of carbon atoms in one molecule.
- Alkyne Group is a carbon-carbon triple bond. The compounds containing the alkyne group are known as alkynes. The homologous series of alkynes have the general formula CnH2n-2, where n is the number of carbon atoms in one molecule.
Halo (Alkyl Halide) Group
Depending on whether a chlorine, bromine, or iodine atom is attached to a carbon atom of the organic compound, the halo group can be chloro (-Cl), bromo (-Br), or iodo (-I). Since the elements chlorine, bromine, and iodine are collectively known as halogen, the Chloro, Bromo, and Iodo groups are referred to as halo groups and are denoted by the symbol -X.
Haloalkanes are formed when one hydrogen atom in an alkane is replaced with a halogen atom. Haloalkanes have the general formula CnH2n+1X, where X represents the halogens. R-X is the formula for haloalkanes, where R is an alkyl group and X is the halogen atom.
One oxygen and one hydrogen atom are joined together to form the alcohol group (-OH) and they are also known as the hydroxyl group. Any class of organic compounds that include one or more hydroxyl (OH) groups linked to a carbon atom of the alkyl group is an alcoholic group.
Alcohols are organic water (H2O) derivatives in which one of the hydrogen atoms has been replaced by an alkyl group, which is often represented by R in organic structures.
Ethanol [C2H5OH] and methanol [CH3OH] are the most common examples of alcohol. The homologous series of alcohols have the general formula CnH2n+1OH. Alcohols are employed as sweeteners and in the manufacture of perfumes, as well as being important intermediates in the synthesis of other compounds.
One carbon atom, one hydrogen atom, and one oxygen atom are joined together to form the aldehyde group (-CHO). Any organic compound in which a carbon atom has a double bond with an oxygen atom, a single bond with a hydrogen atom, and a single bond with another atom or group of atoms (designated R in general chemical formulas and structure diagrams) is called an aldehyde.
Aldehydes have the general molecular formula CnH2nO, where n is the number of carbon atoms in one molecule. Many aldehydes have pleasant scents, and they are created by dehydrogenation (removal of hydrogen) from alcohols, which is how the term “aldehyde” was derived. The two simple aldehydes are formaldehyde HCHO also known as methanal and acetaldehyde CH3CHO also known as ethanal.
One carbon atom and one oxygen atom make up the ketone group (-CO-). The presence of a carbonyl group, in which the carbon atom is covalently bonded to an oxygen atom, distinguishes ketone from other organic molecules. Other than oxygen carbon is attached to the alkyl groups or hydrocarbon radicals (R) form the remaining two bonds.
Since a ketone group is always found in the middle of a carbon chain, a ketone must have at least three carbon atoms in its molecules, one ketone group carbon atom, and two carbon atoms on both sides. Ketones with less than three carbon atoms are not really possible. Ketone has the general molecular formula CnH2nO where n is the number of carbon atoms in one molecule. The simplest ketone is acetone CH3COCH3, also known as propanone.
The physiological effects of ketone molecules are significant. They can be present in a variety of sugars as well as pharmaceutical chemicals such as natural and synthetic steroid hormones. The anti-inflammatory drug cortisone contains three ketone groups in its molecules.
Carboxylic Acid Group
Carboxylic acids, often known as organic acids, are organic molecules that include the carboxylic acid group. Carboxylic acids are sometimes known as alkanoic acids.
The carbonyl (C=O) and hydroxyl (-OH) groups together make up the carboxyl (-COOH) group, where carbon from carbonyl group is attachd to hydroxyl group with single bond.
The homologous series of carboxylic acids have the general formula R-COOH, where R represents an alkyl group. Acetic acid CH3COOH also known as ethanoic acid is the most common carboxylic acid.
The image added below shows the nomenclature of the various functional groups.
The Ether group is similar to alcohols but instead of hydrogen, there is an alkyl group attached to oxygen. The oxygen molecule (-O-) is attached to two alkyl groups (R and R’) with a single bond, forming the ether group. R-O-R’ is the general formula for the ether group. Ethers are very useful and diverse compounds as they are used in the formation of resins, dyes, plastic, paints, oils, etc.
Functional Group Table
The table of most of the useful functional groups is as follows:
|Functional Group and Formula||Suffix||Example|
|Halo Alkanes, R-X||Alkyl Halide||Ethyl Chloride|
|Alcohol, R-OH||-ol||Butanol, Propanol|
|Aldehyde, R-CHO||-al||Methnal (Formeldehyde)|
|Carboxylate, R-COO–||-oate||Sodium Ethanoate (Sodium Acetate)|
|Carboxylic Acid, R-COOH||-oic acid||Ethanoic Acid (Acetic Acid)|
|Ester, R-(CO)-O-R’||Alkyl Alkanoate||Ethyl Butanoate (Ethyl Butyrate)|
|Acyl Halide, R-(CO)-X||-oyl halide||Ethanoyl Chloride (Acetyl chloride)|
|Ether, R-O-R’||Alkyl Ether||Diethyl Ether (Ethoxyethane)|
Nomenclature of Common Functional Groups
The nomenclature is the systematic way of naming organic molecules with a set of rules established by the IUPAC (International Union of Pure and Applied Chemistry). The basic rules of this system are as follows:
- Firstly, identify the longest chain in the organic compound.
- Number the chain of carbon from the side which contains a higher-priority functional group.
- Name the chain with the prefix meth, eth, prop, but, pent, etc with respect to the number of carbon present in the longest chain.
- Name the functional group of the compounds using the appropriate suffixes according to the present functional group.
- If there is more than one functional group present in the chain, the highest priority functional group decides the suffix, and other functional groups are used as a prefix, with alphabetic order (if there is still more than one functional group left after deciding the suffix)
Example: Name the organic compound, CH3CH2CHClCOOH.
Number the carbon atoms in the given compound, from -COOH side as it is the most reactive group in the given compound. i.e.,
As, there are 4 carbon in the longst present chain. It’s name starts with bute, and there is chlorine at second carbon.
Thus, its name is 2-chloro buten-1-oic acid.
Example: What is the IUPAC name of the organic compound CHClBrCH2CHO?
Number the carbon atoms in the given compound, from -CHO side as it is the most reactive group in the given compound. i.e.,
As there are 3 carbon present in the longest chain, it’s name starts with prop root word and there are bromine and cholrine attached to the third carbon.
Thus, name of the given compounds is 3-bromo-3-cholor propen-1-al
Learn more about, Nomenclature of Alcohols, Phenols, and Ethers
Sample Questions on Functional Groups
Question 1: Write the molecular formula for the alcohol group with 4 carbon atoms.
The molecular formula for the alcohol group is CnH2n+1OH. If there are 4 carbon atoms then n=4, this means C4H2(4)+1OH or C4H9OH. So the required molecular formula is C4H9OH
Question 2: Can the compound C2H4O be a ketone group?
A ketone must have at least three carbon atoms in its molecules, one ketone group carbon atom, and two carbon atoms on both sides. Ketones with less than three carbon atoms are not really possible. In the given compound, we have 2 carbon atoms, so it is not a ketone group.
Question 3: What is the molecular formula of aldehyde which is derived from butane?
Aldehydes have the general molecular formula CnH2nO, where n is the number of carbon atoms in one molecule. Since butane C4H10 has 4 carbon atoms, so n=4, this means C4H2(4)O or C4H8O. Hence the molecular formula of aldehyde which is derived from butane is C4H8O.
Question 4: Identify the functional group present in the compound C3H8O.
In the given compound C3H8O, the number of carbon atoms is 3, so n=3. First check if it satisfies the molecular formula of alcohol, aldehyde, ketone, or carboxylic acids. Since it has only one oxygen atom, so it cannot be a carboxylic group. Alcohol has the general molecular formula CnH2n+1OH, where n is the number of carbon atoms in one molecule. Put n=3 in this formula, we get C3H2(3)+1OH or C3H7OH or C3H8O which matches the given compound. So the given compound have alcohol as its functional group.
Question 5: Write the molecular formula for the alkene group and alkyne groups containing 5 carbon atoms.
Given that there are 5 carbon atoms, so n=5. Alkenes have the general formula CnH2n, where n is the number of carbon atoms in one molecule. Put n=5 in this formula, C5H2(5) or C5H10.
Alkynes have the general formula CnH2n-2, where n is the number of carbon atoms in one molecule. Put n=5 in this formula, so C5H8 or C5H8.
Hence the molecular formula for the alkene group is C5H10 and the alkyne group is C5H8.
Hydrogenation of Oils
An addition reaction occurs when an unsaturated hydrocarbon reacts with another substance to produce a single product. All unsaturated hydrocarbons with a double or triple bond give rise to addition reactions. This indicates that all alkenes and alkynes provide addition reactions. Now we’ll look at an addition reaction that involves adding hydrogen to unsaturated hydrocarbons with carbon-carbon double bonds. When ethene is heated in the presence of a nickel catalyst, it combines with hydrogen to produce ethane.
CH2=CH2 + H2 → CH3-CH3
(Ethene) (Hydrogen) (Ethane)
In this reaction, one hydrogen atom (H) is added to each carbon atom (C) in ethene, enabling the double bond to break and ethane to become a single bond. In general, unsaturated hydrocarbons add hydrogen to produce saturated hydrocarbons in the presence of catalysts such as nickel (Ni). Hydrogenation is the process of adding hydrogen to an unsaturated hydrocarbon to produce a saturated hydrocarbon.
The hydrogenation reaction occurs in the presence of nickel metal, which acts as catalysts. The hydrogenation process is widely used in industry, and it is used to make vegetable ghee or vanaspati ghee from vegetable oils.
Groundnut oil, cotton oil, and mustard oil are examples of unsaturated molecules with double bonds. At room temperature, they are in a liquid condition. Vegetable oils, like alkenes, undergo hydrogen addition to generate a saturated product called vegetable ghee or vanaspati ghee, which is solid or semi-solid at room temperature due to the presence of double bonds. The addition of hydrogen to vegetable oil, known as hydrogenation, results in vegetable ghee, also known as vanaspati ghee.
Example of Hydrogenation of Oils
Unsaturated fats with double bonds between some of their carbon atoms are called vegetable oils. A saturated fat called vegetable ghee or vanaspati ghee is generated when a vegetable oil, such as groundnut oil, is heated with hydrogen in the presence of finely divided nickel as a catalyst. This process is known as the hydrogenation of oil and can be represented as follows.
Hydrogenation of Oils.
Unsaturated fatty acids found in vegetable oils are beneficial to human health. As a result, cooking should be done with oil. Sunflower oil, soyabean oil, and groundnut oil are some of the most used cooking oils. Sundrop, Saffola, Fortune, and Dalda refined oil are some of the brand names available in the market. Saturated fats, such as vegetable ghee, which are made by hydrogenation of oils, are bad for your health. They are sold under the brand name Dalda among others, in the market. Saturated fats from animals, such as butter and desi ghee, contain saturated fatty acids, which are said to be harmful to one’s health if consumed in large amounts.
Uses of Hydrogenated Oils
As a preservative, hydrogenated oil is used by food manufacturers. It’s also used to improve flavour and texture. Food manufacturers use hydrogenated oils in their products for a variety of reasons, which are listed below.
- Food preservation
- Enhancing the sense of taste
- Texture enhancement
To improve taste and texture, manufacturers utilize a combination of oils rather than partially hydrogenated oils.
Question 1: Which catalyst is used in the hydrogenation of oil?
Nickel catalyst is used in the commercial hydrogenation of edible oils.
Question 2: In the hydrogenation of oils, what gas is used?
In the presence of nickel as a catalyst, hydrogen gas is used to hydrogenate oils.
Question 3: In the hydrogenation of oil, why is nickel used as a catalyst?
Since the atomic structure of nickel is such that it attracts the atoms of hydrogen and unsaturated compounds to its surface where they come in contact with each other and react to form the saturated compound.
Question 4: Name some foods that contain hydrogenated oil.
Some foods that contain higher levels of hydrogenated oils are canned frostings, baked goods, snack foods, etc.
Question 5: How do you know if an oil is fully hydrogenated?
The chemical process of hydrogenation transforms liquid vegetable oil into solid fat. Oils that have been partially hydrogenated are semi-soft, and fully hydrogenated oils are firmer.
Question 6: Among the hydrocarbons CH4, C2H2, which one undergoes the addition reaction?
Only the unsaturated hydrocarbons, i.e., alkenes and alkynes undergo the addition reaction. Out of the given hydrocarbons, CH4 is an alkane and C2H2 is an alkyne. So, C2H2 undergoes the addition reaction.
What is Ethanol?
Ethanol is the second member of the homologous series of alcohol whose first member is methanol. Ethanol is also known as Ethyl alcohol which is the most prevalent and commonly used alcoholic beverage, therefore it is sometimes referred to simply as alcohol.
Ethanol is produced at a large scale using the fermentation of carbohydrates (the method used for alcoholic beverages) and the hydration of ethylene. In the fermentation process, yeast is used to convert carbohydrates (sugarcane, beets, wheat, corn, etc.) to ethanol, and in the hydration of ethylene method, ethanol is produced by passing a mixture of ethylene and steam over an acidic catalyst t temperature and pressure.
Ethanol Molecular Formula
One molecule of Ethanol contains two atoms of Carbon, one atom of Oxygen, and 6 atoms of Hydrogen, thus the molecular formula of Ethanol is C2H5OH, where -OH represents the alcohol functional group in the formula. Sometimes this formula can be written in the form C2H6O, which doesn’t clear anything about ethanol’s structure or containing functional group. Thus, the formula of ethanol written in the form C2H5OH is more useful and informational.
Ethanol Molecular Weight
The Molecular weight of Carbon, Oxygen, and Hydrogen respectively are 12, 16, and 1. Thus, the molecular weight or atomic weight of ethanol can be calculated using the sum of all the individual atoms of the compound.
The molecular Weight of Ethanol is 12 × 2 + 16 + 1 × 6 = 46 a.m.u.
Ethanol has one functional group i.e., -OH or alcohol group, and the structure of ethanol can be given by the following diagram.
Physical Properties of Ethanol
The following are some of the physical properties of ethyl alcohol:
- Ethanol is a colorless liquid with a pleasant odor and a burning flavor.
- Ethanol or ethyl alcohol is a very volatile liquid with a low boiling point of 78.5 °C.
- The melting point and flash point (the temperature at which any organic compound gives off sufficient vapor to ignite the air) of Ethanol are respectively -114 °C and 9-11 °C.
- As the specific gravity of ethanol is 0.8, thus it has a lower density than water.
- Ethanol is soluble in water and can be mixed with water in any ratio, this is due to the presence of a hydroxyl group in ethyl alcohol contributing to its water solubility.
- Ethanol is neutral in nature since it contains no hydrogen ions. As a result, no litmus solution is altered by ethyl alcohol.
- Ethyl alcohol is a covalent compound.
Chemical Properties of Ethanol
Some of the chemical properties of ethanol include combustion, oxidation, dehydration, esterification, and reaction with sodium metal, which are explained as follows:
The liquid ethyl alcohol is extremely flammable. It easily catches fire and begins to burn. It quickly burns in the air, producing carbon dioxide and water vapor as well as a large amount of heat and light.
C2H5OH + 3O2 → 2CO2 + 3H2O + Heat + Light
(Ethanol) (Oxygen) (Carbon dioxide) (Water vapor)
Controlled combustion is referred to as oxidation. Ethyl alcohol is oxidized to ethanoic acid when heated with an alkaline potassium permanganate solution of acidified potassium dichromate solution(or any other strong oxidizing agent). To perform this reaction, dropwise add a 5% aqueous potassium permanganate in sodium hydroxide solution to ethyl alcohol until the purple color of the potassium permanganate solution no longer exists. Ethyl alcohol is oxidized to ethanoic acid when the test tube holding ethyl alcohol and alkaline potassium permanganate solution is gently warmed in hot water. This reaction, which is carried out in the presence of an alkaline potassium permanganate solution, is given below.
CH3CH2OH + 2[O] → CH3COOH + H2O
(Ethanol) (Nascent oxygen) (Ethanoic acid) (Water)
Dehydration refers to the loss of water molecules from alcohol. When ethyl alcohol is heated to 1700C with excess concentrated sulfuric acid, it dehydrates to generate ethene. The concentrated sulphuric acid acts as a dehydrating agent, removing water molecules from the ethyl alcohol molecule in this reaction. At 1700C, this reaction takes place in the presence of concentrated H2SO4.
CH3CH2OH → CH2=CH2 + H2O
(Ethanol) (Ethene) (Water)
Reaction with Sodium Metal
Sodium ethoxide and hydrogen gas are formed when ethyl alcohol reacts with sodium. This reaction is used to detect the presence of ethyl alcohol.
2C2H5OH + 2Na → 2C2H5O–Na+ + H2
(Ethanol) (Sodium) (Sodium ethoxide) (Hydrogen)
When the Alcohal group reacts with carboxylic acid, the product of this reaction is ester, which is why it is called esterification. The reaction of Ethanol with Ethanoic acid is one example of esterification, i.e., when ethyl alcohol is heated in the presence of a few drops of strong sulphuric acid, it combines with ethanoic acid to form ethyl ethanoate, a sweet-smelling ester. Esterification is the reaction in which a carboxylic acid reacts with an alcohol to form an ester.
C2H5OH + CH3COOH → CH3COOC2H5 H2O
(Ethanol) (Ethanoic acid) (Ethyl ethanoate) (Water)
Ethanol is used in modern times very aggressively in many fields, some of those applications are as follows:
- Alcoholic Beverages
- Ethanol Blending
- Chemical Synthesis
Most alcoholic beverages have Ethanol and water as their main components, other than ethanol other alcohol compounds, carbonyl compounds such as aldehyde, hydroxy acids, etc. are also present in these beverages in minute quantities.
When ethanol is mixed with traditional fuel such as petrol to create a new fuel blend, this process is called ethanol blending. It is done to reduce greenhouse gas emissions and increase the octane rating of the fuel. Also as ethanol is a renewable biofuel that can be created using the fermentation of carbohydrates such as sugar cane and corn.
Learn more about, Ethanol Blended Petrol
For the synthesis of many organic compounds such as esters, acetic acid, diethyl ether, ethyl amines, etc, ethanol is used as a raw material.
In the fragrance and perfume industries, ethanol is used as a solvent for essential oils and fragrances and can carry them from the bottle to the place of application.
In hospitals and medications, ethanol or other alcohol is used for many purposes such as sterilizing wounds, as hand sanitizer for doctors, cleaning the thermometer, etc.
Harmful Effects of Drinking Alcohol
We should not consume alcoholic beverages because of the following negative consequences.
- When you consume a large amount of alcohol on a single occasion, you will experience staggering movement, slurred speech, blurred vision, dizziness, and vomiting. A man becomes unconscious after consuming large amounts of alcohol and may even die.
- Since alcohol reduces the activity of the nervous system and the brain, a person’s judgment is compromised and his reaction is slowed. As a result, a driver under the influence of alcohol is unable to assess the situation accurately or respond swiftly in an emergency. As a result, drunken driving causes a rise in traffic accidents.
- Drinking a lot of alcohol for a long time can harm your stomach, liver, heart, and even your brain. Alcohol-induced liver damage, known as ‘cirrhosis,’ can be fatal.
- As a result of the loss of inhibitions caused by alcohol consumption, a drunken person gets irritable. As a result, there are more quarrels and clashes, which leads to a rise in violence and crime in society.
- A person who consumes a lot of alcohol becomes addicted to it.
- Drinking methyl alcohol-containing contaminated alcohol produces severe poisoning, which can result in blindness and even death.
In the manufacturing of various items, a lot of ethyl alcohol is used. The government does not charge a production tax on ethyl alcohol used for industrial purposes. As a result, industrial alcohol is significantly less expensive than commercial alcohol. To prevent industrial alcohol from being used for drinking or black market purposes, it is denatured by adding small amounts of harmful substances such as methanol, pyridine, or copper sulphate, among others.
The harmful compounds added to ethyl alcohol make it unfit for consumption. Denatured alcohol is ethyl alcohol that has been made unfit for drinking by adding small amounts of harmful substances such as methanol, pyridine, copper sulfate, and other poisonous substances. A little amount of copper sulfate is added to industrial ethyl alcohol to give it a blue color that makes it easy to identify.
What are Soaps?
Soap is produced by saponification reaction between sodium hydroxide or potassium hydroxide and vegetable oil or animal fats. Thus, soaps are potassium or sodium salts of a long chain of fatty acids. Soaps are water-soluble in nature.
Saponification reaction is the reaction between an ester and base to give alcohol and soap as the products. The general form of saponification reaction is shown below.
Ester + Base → Alcohol + Soap
Properties of Soaps:
- Hard in nature: Soaps are generally hard in nature i.e. they are in solid form.
- Cleansing Action: Soaps are effective to clean away the dirt from a surface. Soaps have a hydrophobic tail and hydrophilic head which are equally important in the cleaning process.
- Lather formation: Soaps form lather with soft water.
- Conditioners: Soaps contain conditioners called emollients that are responsible to moisturize our skin once we use the soap.
- Fragrant: Soaps generally have a unique fragrance added to them. These fragrances help calm us, soothe our minds and remove our body odours.
Structure of Soap
A soap molecule is a sodium or potassium salt of a long chain of fatty acids. Thus soap has two parts, one is the ionic part and the other is a long carbon chain. The two parts of the soap molecules possess very different properties. These two parts are known as:
- Hydrophobic tail: This part of the soap is water repellent in nature and dissolves in oils. It is ionic in nature.
- Hydrophilic head: This part of the soap molecule is water attractive or water-loving and dissolves in water. It is made up of a long chain of hydrocarbons.
As shown in the above image the soap molecule has a hydrophilic head which is generally the ionic part and a hydrophobic tail which is a long hydrocarbon chain and is generally represented using R. An example of soap is C17H35COO−Na+.
Structure of Soap.
Cleansing Action of Soap
The dirt is generally oily in nature and insoluble in water. The soap cleanses the dirt by the process of micelle formation. Before we study the cleansing action of soap in detail, we need to understand what micelle is.
What is micelle?
A micelle is formed by the cluster of molecules where the molecules arrange themselves in a spherical shape with the hydrophobic end facing inwards and the hydrophilic end facing outwards.
The soap molecules form micelles in water and perform cleansing action as follows:
- As we know soap has a hydrophobic and hydrophilic part, so when the soaps are dissolved in water, the hydrophilic end is attracted by water and faces outwards while the hydrophobic tail is repelled by water and faces inwards. The below image shows soap molecules with the hydrophobic end facing away from water while the hydrophilic end facing towards water.
- Now, these molecules start aggregating around the dirt molecule with the hydrophilic head outwards and the hydrophobic tail towards the dirt molecule i.e. away from the water and form a spherical cluster of molecules that are known as a micelle. Micelle formation by soap molecule is shown below in the image.
- The soap molecule in form of micelles can clean the dirt as the dirt is now trapped within the micelle.
- The micelles formed to make a colloidal solution with the water.
- When the cloth or surface is washed with soap and water, the hydrophilic end gets attracted by water and the dirt molecule that has been trapped inside the micelle gets washed away with the water.
- This is how the cleansing action of soaps take place.
Advantages of soaps:
- Soaps are readily available, cheap and convenient to use.
- Soaps are very effective for cleaning in soft water
- They are 100% biodegradable in nature and do not cause pollution as they are easily degradable by the bacteria in the sewerage.
Disadvantages of soap:
- Soaps are not effective for cleaning in hard water as they form scum with hard water instead of lather formation. The reaction of soap with magnesium ions in hard water is shown below. Soaps react with magnesium and calcium ions from hard water to form calcium or magnesium salts of fatty acids which do not dissolve in water and form a white precipitate that is called scum.
2RCOO−Na+ + Mg2+ → (RCOO)2Mg + 2Na+
- Scum sticks to clothes and makes washing difficult
- Highly branched soaps are not easily degradable and cause pollution.
- As soaps are basic in nature, they cannot be used to clean woollen garments as they have acidic dyes.
Question 1: Define soaps.
Soaps are sodium or potassium salts of vegetable fats and are produced as a result of saponification reaction i.e. reaction between sodium or potassium hydroxide and vegetable oil or animal oil. Soaps are soluble in water.
Question 2: What are the two parts of soap molecules?
The two parts of soap molecule are:
- Hydrophobic tail: This part of soap is water repellent in nature and dissolves in oils.
- Hydrophilic head: This part of soap molecule is water attractive or water loving and dissolves in water.
Question 3: State two properties of soaps?
The 2 properties of soap molecules are as follows:
- Cleansing Action: Soaps are effective to clean away the dirt from a surface.
- Lather formation: Soaps form lather with soft water.
Question 4. What are the disadvantages of soaps?
Disadvantages of soap are:
- Soaps are not effective for cleaning in hard water as they form scum with hard water instead of lather formation
- Scum sticks to clothes and makes washing difficult
- Highly branched soaps are not easily degradable and cause pollution.
Question 5: Define micelle.
A micelle is the aggregate cluster of molecules where the molecules arrange themselves in a spherical shape with the hydrophobic end facing inwards and the hydrophilic end facing outwards.
Question 6: State the reaction of soap in hard water.
The reaction of soap in hard water is as follows:
2RCOO−Na+ + Mg2+ → (RCOO)2Mg + 2Na+
Here RCOO−Na++ is the soap molecule which reacts with Mg+2 ions from hard water to form scum i.e. (RCOO)2Mg.
What are Soaps and Detergents?
Soaps and detergents are the basic cleaning product that are used for cleaning various objects, soaps are generally used to clean soft and delicate objects such as human skin and others, whereas detergents are used to clean rough objects and they have a rough action on the human skin. Soap and Detergents are called Surfactants as they reduce the surface tension of water.
Now let’s learn about soap and others in detail in this article.
Soap is a compound made by combining Sodium Hydroxide or Potassium Hydroxide with vegetable oil or animal fats in a saponification reaction. Soaps are potassium or sodium salts of fatty acids with a long carbon chain. Soaps are naturally water-soluble.
A soap molecule is made up of two components. These two components are referred to as:
- Hydrophobic tail: This part of the soap is water-repellent in nature and dissolves in oils. It is ionic in nature.
- Hydrophilic head: This part of the soap molecule is water attractive or water-loving and dissolves in water. It is made up of a long chain of hydrocarbons.
Properties of Soap
Soap of have various properties that differentiate them from detergents. Some of the properties of the soap are,
- Soaps are large chain aliphatic compounds. They are formed by reacting Potassium or Sodium salts with fatty acids
- Soaps are prepared using a reaction called saponification.
- Soaps are the substances that reduces the surface tension of the liquid in which they are dissolved.
- A soap molecule has two parts a Hydrophobic tail and a Hydrophilic head.
Manufacturing of Soap
A soap consists of long-chain fatty acids with a metal ion head. Soaps are sodium or potassium salt of long-chain fatty acid. The process of making soap is called saponification. In Saponification, oil and fat are heated and then reacted with alkali which results in the formation of soap, water, and glycerine. The other process of making soap is Neutralization. In the Neutralization method, oil and fats are hydrolyzed with the help of high-pressure steam which results in the formation of Glycerine and crude fatty acid. The so-formed fatty acid then undergoes distillation and is then neutralized by alkali to produce soap and water.
Detergents are compounds that have ionic groups connected to the end of a lengthy hydrocarbon chain. Detergents are long-chain carboxylic acid quaternary ammonium or sulfonate salts.
Detergents, often known as surfactants, are substances that lower water’s surface tension. Detergents were developed during World War 2 due to the lack of vegetable oils to make soaps. Detergents also contain two parts.
- Hydrophobic Tail: This part of the detergent is water-repellent similar to the soaps. It is the ionic or polar or charged group that is present at the end of the hydrocarbon chain.
- Hydrophilic Head: This part is water attractive or water-loving. It is made up of a long alkyl hydrocarbon chain.
Types of Detergents
Detergents are further classified into 3 types depending on the polarity of the polar group or hydrocarbon chain. These are:
- Cationic Detergents
- Anionic Detergents
- Non-ionic detergents
Properties of Detergents
Various properties of the detergents are,
- Detergents are Potassium or Sodium salts of a long alkyl chain that contains a sulfonate group at the end of it.
- Detergents are water-soluble compounds.
- Detergents reduce the surface tension of water and are called surfactants.
- Detergents are soluble in water like soaps. Detergents are even soluble in hard water and do not form scum so they overcome the major limitation of soap.
- This is because the ionic group present in detergents does not interact with the Mg or Ca ions present in hard water.
Manufacturing of Detergent
Detergents are manufactured by two methods, anionic surfactant, and non-ionic surfactant method. In Anionic Surfactant Method, hydrocarbons that are derived from petrochemicals react chemically to produce acids that resemble fatty acids. These newly produced acids are reacted with alkali to give an anionic surfactant. In the Non-Ionic surfactant method, hydrocarbons are first converted to alcohol which then is reacted with ethylene oxide. After the reaction with ethylene oxide, it is then reacted with acid-containing atoms of sulfur to give another anionic surfactant.
Difference between Soap and Detergent
The difference between soap and detergent is that soap is a fatty acid and detergent is a combination of surfactants. We use them to clean the house. To distinguish between soap and detergent, we must analyze their characteristics:
|1.||Soaps are sodium or potassium salts of a long chain of carboxylic acids.||Detergents are ammonium or sulfonate salts of long chains of carboxylic acids.|
|2.||Soaps are mostly biodegradable.||Detergents are non-biodegradable.|
|3.||Soaps do not clean well in hard, acidic, and saline water.||They are effective in hard, saline, and acidic water as well.|
|4.||They form scum with hard water.||They form lather with hard water.|
|5.||They are made from natural compounds such as fatty acids or vegetable or animal fats.||Detergents are synthetically derived from chemicals.|
|6.||Soap is generally prepared from plant and animal fats through saponification.||Petroleum (Petrochemicals) was found to be a plentiful source for the manufacture of detergent.|
|7.||Soaps are not ionic in nature.||Detergents may be cationic, anionic, or non-ionic in nature.|
|8.||They are not effective in hard water and saline water||They do not lose their effectiveness in hard water and saline water.|
|9.||Examples: Sodium Stearate||Examples: Sodium lauryl sulfate|