Revising Carbon and Its Compounds (Science Class X)

Versatile nature of carbon/catenation: A carbon atom is tetravalent element i.e., it has 4 valance electrons, so it can form 4 covalent bonds with other atoms. Further because of small size and tetravalency, carbon atoms show a great tendency to form long chains by combining with each other.

Q. Give reason: The element carbon forms a very large number of compounds.

Q. Why does carbon has maximum tendency for catenation?

Hydrocarbon: Compounds of carbon and hydrogen are called hydrocarbons. Hydrocarbons that have single bonds only are called saturated hydrocarbons. Hydrocarbons that have multiple bonds i.e,. single or double bonds are called unsaturated hydrocarbons.

Q. What are hydrocarbons?

Q. What is the difference between a saturated and an unsaturated hydrocarbon?

Q. What do you mean by homologous series?

Nomenclature: Naming of the carbon compounds is done according to the following two rules give by IUPAC.

• The longest continuing chain of carbon atoms should be identified first.
• The presence of a functional group is indicated by adding either a suffix or prefix to the base or root name.

(Refer to section 4.2.5 Nomenclature of Carbon Compounds in your NCERT text book.)

Q. In an organic compound, which parts largely determine its physical and chemical properties?

Q Name the following compound:

Q. Give the names of the functional groups: (i) — CHO  (ii) — OH

Q. Write the chemical formula of the simplest ketone.

Q. Write the formulae for the given compounds and name the functional groups present in each of them:
(i) Ethanoic acid (ii) Propanone (iii) Nitromethane

Chemical properties of carbon:

• Combustion: All the hydrocarbons produce carbon dioxide and water after combustion along with a large amount of energy in the form of heat.

Q. Name the product other than water formed on burning of ethanol in air

• Addition and substitution reactions: All the saturated hydrocarbons undergo substituting reactions while unsaturated hydrocarbons undergo addition reactions. Hydrogenation of vegetable oil into vegetable ghee is an example of addition reaction.

Q. What is Hydrogenation reaction? Give one industrial application of this.

Ethanol and Ethanoic acid: Ethanol and ethanoic acid both are the second members of alcohol and carboxylic acid homologous series. They undergo various chemical reactions. The following two chemical reactions are the most important.

o Esterification reaction

o Saponification reaction.

Q. What happens when a small piece of sodium is dropped into ethanol?

Q. Distinguish between esterification and saponification reactions of organic compounds.

Q. With a labelled diagram describe an activity to show the formation of an ester.

Q. Write a chemical equation to represent the reaction of ethanol with acidified solution of potassium dichromate?

Q. What is vinegar?

Q. Describe with a chemical equation, what happens when sodium hydrogen carbonate reacts with ethanoic acid?

Q. Four students observed the colour and odour of acetic acid and its reaction with sodium hydrogen carbonate. They tabulated their observations as given below.

The correct set of observation is that of student:

(1) A  (2) B  (3) C  (4) D

Q. A student mixed some acetic acid with water. He would observe the solution formed as

(1)  Green and transparent

(2)  Pink and opaque

(3)  Yellow and transparent

(4)  Colourless and transparent

Q. Name the organic acid present in vinegar. Write a chemical equation which represents the commercial method for the preparation of this acid from methanol.

Q. Give reasons for the following:

(a) Alcohol supplied for industrial purposes is mixed with poisonous substances such as copper sulphate.

(b) The reaction CH₃COONa + NaOH ® CH₄ + Na₂CO₃ is classified as a decarboxylation reaction.

(c) Formalin is used for preserving biological specimens.

Soap and detergents:

• Soaps are sodium and potassium salts of long chain fatty acids containing 12 to 18 carbon atoms. Soaps are made from natural fats and oils and so are fully biodegradable, so it does not cause any water pollution.
• Detergents are ammonium or sulphonate salts of long-chain carboxylic acids. They do not react with calcium and magnesium salts present in the water and give good lather. Detergents are nonbiodegradable and cause water pollution.

Q. Explain the use of synthetic detergents causes pollution of water.

Q. What are detergents? What change has been made in detergents to make them easily bio-degradable? Explain the cleansing action of detergents.

Q. Differentiate between a soap and a detergent on the basis of their chemical constitutions. For cleansing action when is a detergent preferred over a soap?

All the best!

Team Meritnation