Solutions of Chemical Reactions and Equations (Page No - 48) - Chemistry Lakhmir Singh, Class 10 | Extra Documents, Videos & Tests for Class 10 PDF Download

Question 43:
(a) Explain the term “corrosion” with an example. Write a chemical equation to show the process of corrosion of iron.
(b) What special name is given to the corrosion of iron ?
(c) What type of chemical reaction is involved in the corrosion of iron ?
(d) Name any three objects (or structures) which are gradually damaged by the corrosion of iron and steel.
Solution :
(a) Corrosion is the process in which metals are eaten up gradually by the action of air, moisture or a chemical (such as an acid) on their surface. Rusting of iron metal is the most common form of corrosion.
During the corrosion of iron, iron metal is oxidised by the oxygen of air in the presence of water (moisture) to form hydrated iron oxide called rust.

(b) Rusting.
(c) Oxidation.
(d) Railings, car bodies and bridges.

Question 44:
(a) Explain the term “rancidity”. What damage is caused by rancidity ?
(b) What type of chemical reaction is responsible for causing rancidity ?
(c) State and explain the various methods for preventing or retarding rancidity of food.
Solution :
(a) The condition produced by aerial oxidation of fats and oils in foods marked by unpleasant smell and taste is called rancidity. It spoils the food materials prepared in fats and oils which have been kept for a considerable time and makes them unfit for eating.
(b) Oxidation.
(c) Rancidity can be prevented by adding anti-oxidants to foods containing fats and oils.

1. It can be prevented by packaging fat and oil containing foods in nitrogen gas.
2. Rancidity can be retarded by keeping food in a refrigerator.
3. Rancidity can be prevented by storing food in air-tight containers.
4. Storing foods away from light can also prevent rancidity.

Question 45:
(a) What happens when an aqueous solution of sodium sulphate reacts with an aqueous solution of barium chloride ?
(b) Write the balanced chemical equation for the reaction which takes place.
(c) State the physical conditions of reactants in which the reaction will not take place.
(d) Name the type of chemical reaction which occurs.
(e) Give one example of another reaction which is of the same type as the above reaction.
Solution :
(a) When barium chloride solution is added to sodium sulphate solution, then a white precipitate of barium sulphate is formed along with sodium chloride solution.

(c) Solid sodium sulphate and Solid barium chloride
(d) Double displacement reaction.
(e) Double displacement reaction between silver nitrate solution and sodium chloride solution forms a white precipitate of silver chloride and sodium nitrate solution.