Acids, Bases and Salts NCERT Solution, study material, CBSE Notes

NCERT Solution: Acids, Bases and Salts

What happens when nitric acid is added to egg shell?

When nitric acid is added to egg shell, it dissolves egg shell. Egg shell is composed of calcium carbonate which dissolves in nitric acid. The reaction between nitric acid and calcium carbonate yields calcium nitrate and carbon dioxide gas.

CaCO₃ + HNO₃ → Ca(NO₃)₂ + CO₂ + H₂O

A student prepared solutions of (i) an acid and (ii) a base in two separate beakers. She forgot to label the solutions and litmus paper is not available in the laboratory. Since both the solutions are colourless, how will she distinguish between the two?

The student can use other indicator; like phenolphthalein or methyl orange to check the acidity or alkalinity of a particular solution. The student can also use turmeric powder to check the solutions. It is mentioned that litmus paper is not available. So, we can assume that the laboratory may have other indicators.

How would you distinguish between baking powder and washing soda by heating?

When baking powder is heated, carbon dioxide is produced. This can be shown by following equation.

2NaHCO₃ + Heat → Na₂CO₃ + CO₂ + H₂O

Evolution of carbon dioxide can be confirmed by passing the gas into lime water. if lime water turns milky, it indicates evolution of carbon dioxide gas. This reaction does not happen when washing soda is heated.

Salt A commonly used in bakery products on heating gets converted into another salt B which itself is used for removal of hardness of water and a gas C is evolved. The gas C when passed through lime water, turns it milky. Identify A, B and C.

Salt A is sodium hydrogen carbonate (baking soda). When it is heated, it turns into sodium carbonate; which is salt B. In this reaction, carbon dioxide gas is also produced; which is the gas C.

2NaHCO₃ + Heat → Na₂CO₃ + CO₂ + H₂O

Sodium hydrogen carbonate is used in bakery products. Sodium carbonate is used for removing hardness of water.

In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with lime water to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y giving the chemical equation of the reactions involved.

Sodium chloride is subjected to chloralkali process to manufacture sodium hydroxide. Chlorine and hydrogen gas are formed during this process.

2NaCl + 2H₂O → 2NaOH +Cl₂ +H₂

Chlorine reacts with lime water to give bleaching powder.

Ca(OH)₂ + Cl₂ → CaOCl₂ +H₂O

X is chlorine. Y is bleaching powder.

Fill in the missing data in the following table.

ANS

What are strong and weak acids? In the following list of acids, separate strong acids from weak acids. Hydrochloric acid, citric acid, acetic acid, nitric acid, formic acid, sulphuric acid.

Acids which get completely ionized in aqueous solution are called strong acids, e.g. hydrochloric acid, nitric acid and sulphuric acid. Acids which do not get completely ionized in aqueous solution are called weak acids, e.g. acetic acid, citric acid, and formic acid.

When zinc metal is treated with a dilute solution of a strong acid, a gas is evolved, which is utilised in the hydrogenation of oil. Name the gas evolved. Write the chemical equation of the reaction involved and also write a test to detect the gas formed.

Following reaction takes place when zinc is treated with a dilute solution of a strong acid.

Zn +H₂SO₄→ ZnSO₄ + H₂

In this reaction, hydrogen gas is produced; which is utilized in the hydrogenation of oil. When a burning matchstick is brought near hydrogen gas, the matchstick burns with a pop sound. This confirms the evolution of hydrogen gas.