NCERT Solutions for Class 10 Chemistry Chapter 4 : Carbon and its compounds

NCERT Solutions for Class 10 Science Chapter 2 Carbon and its Compounds – Brief Overview

Carbon

Carbon is a necessary ingredient for all life on Earth. Carbon chains are classified into three types: branched, ring, and straight. Carbon is regarded as a significant source of fuel. It is nonmetallic and tetravalent, which means it can form covalent chemical bonds with four electrons. Covalent bonds are formed with oxygen, chlorine, hydrogen, nitrogen, sulphur, and itself. Carbon is one of the most common elements and can be found in a wide variety of compounds, such as carbon dioxide, carbon monoxide, and carbon disulphide.

Allotropes of Carbon

Allotropy, also known as allotropism, is the ability of some chemical elements to exist in two or more different physical states. Carbon has 3 types of allotropes –

1. Diamond – In this, a carbon atom is connected to four other carbon atoms to build three-dimensional structures. It is the toughest and most insulating substance. It is used for drilling and cutting rocks. It's also used to make jewellery.
2. Graphite – Graphite is an allotropic type of carbon composed of hexagonally organized carbon atom layers in a planar condensed ring structure. Each carbon atom is connected to three other carbon atoms in this. It is a good electrical conductor and is used as a lubricant.
3. Buckminster Fullerene – It is a carbon-containing cluster of 60 carbon atoms linked together to create spherical molecules. Each carbon atom is connected by three bonds. At room temperature, it is a black solid.

Homologous Series

A homologous series is a group of hydrocarbons that share the same general formula and have similar chemical characteristics. Methane, ethane, propane, butane, and other alkanes, for example, are all members of the alkane homologous series. A CH₂ unit separates the molecular formulas of two adjacent members of a homologous series. A general formula can represent all the elements of a homologous series:

Alkane – C_nH_2n+2

Alkyne – C_nH_2n-2

Alcohol – C_nH_2n+1OH

Ketone – C_nH_2n+1COC_nH_2n+1

Alkene – C_nH_2n

Haloalkane – C_nH_2n+1X

Aldehyde – C_nH_2n+1CHO

Carboxylic acid – C_nH_2n+1COOH

Chemical properties of carbon compounds

• Combustion Reaction – The combustion reaction is a chemical reaction that occurs when a substance burns in the presence of air or oxygen. Carbon, in all of its allotropic forms, burns in oxygen to produce carbon dioxide as well as heat and light. Example,

C + O₂ → CO₂ + Heat + Light

CH₄ + 2O₂ →  CO₂ + 2H₂O + Heat + Light

• Oxidation Reaction – Oxidation is the addition of oxygen to a substance during burning. In addition to combustion, oxidation can be caused by substances capable of providing oxygen to others, i.e., oxidising agents.
• Addition Reaction – In organic chemistry, an addition reaction is simply an organic reaction in which two or more molecules combine to generate a bigger one in the presence of a catalyst. Catalysts are chemicals that cause a reaction to occur or progress at a different rate without affecting the reaction itself.
• Substitution Reaction – The reactions in which an atom or group of atoms from a molecule is replaced by another atom with no change in structure in the remaining part of the molecule. Example,

CH₄ + Cl₂ →  CH₃Cl + HCl (in the presence of sunlight)