on passing the gas A through B it turns milky. Name the compound formed and write the chemical reaction involved. What will happen if dry compound B reacts with the chlorine gas to form C. Identify the compounds A,B and C and write all the chemical reactions
Answers
NCERT Exemplar Solution Long Answer 2
A metal carbonate X on reacting with an acid gives a gas which when passed through a solution Y gives the carbonate back.
On the other hand, a gas G that is obtained at anode during electrolysis of brine is passed on dry Y, it gives a compound Z, used for disinfecting drinking water. Identity X, Y, G and Z.
Answer: Calcium carbonate gives carbon dioxide gas when reacts with hydrochloric acid.
CaCO3 + 2HCl ⇨ CaCl2 + CO2 + H2O
Carbon dioxide turns lime water milky when passed through it because of formation of calcium carbonate. When carbon dioxide; so formed; is passed through lime water, lime water turns milky because of the formation of calcium carbonate.
CO2 + Ca(OH)2 ⇨ CaCO3 + H2O
On the electrolysis of brine, chlorine gas is deposited over anode which gives calcium oxychloride (Bleaching powder) on passing over slaked lime. The bleaching powder is used in disinfecting the drinking water.
Ca(OH)2 + Cl2 ⇨ CaOCl2 + H2O
Bleaching powder is used for disinfecting drinking water.
Therefore;
Metal carbonate ‘X’ is calcium carbonate.
Solution ‘Y’ is lime water (Calcium hydroxide).
Gas ‘G’ is chlorine gas.
Dry ‘Y’ is dry calcium hydroxide (dry slaked lime).
Compound ‘Z’ is bleaching powder (Calcium oxychloride).
A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by–product of chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.
Answer: Dry pellets of sodium hydroxide absorb moisture and turn sticky when kept in open which is also a byproduct of Chlor-alkali process.
Non-metallic oxides are acidic in nature, such as carbon dioxide. When carbon dioxide reacts with sodium hydroxide it gives sodium carbonate and water. Since sodium hydroxide is a base and solution of carbon dioxide is an acid, so reaction taking place between them is a neutralization reaction.
2NaOH + CO2 ⇨ Na2CO3 + H2O
Therefore, common base ‘B’ is sodium hydroxide. Reaction between ‘B’ and acidic oxide is neutralization reaction.
Answer:
A=carbondioxide B=lime water