- No. ii. Which types of salts produce SO2 gas on reacting with acids?
Answer. When acids react with sulphites and bisulphate’s salt, and SO2 gas is formed. For example, when hydrochloric acid reacts with calcium sulphite it produces calcium chloride and sulphur dioxide gas.
CaSO3 (aq) + 2HCl (aq) CaCI2 (aq) + SO2 (g) + H2O(1)
Similarly, hydrochloric acid reacts with sodium bisulphate to produce sodium chloride and sulphur dioxide gas.
NaHSO3 (aq) + HCl (aq) NaCl(aq) + SO2(g) + H2O(1
- No. iii. Give the uses of sulphuric acid.
Answer. Sulphuric acid is used for manufacturing of fertilizers, (ammonium sulphate) explosives, paints, dyes, drugs and as an electrolyte in lead storage batteries.
- No.iv .Name the gas liberated when alkalis react with ammonium salts.
Answer. When alkalis react with ammonium salt ammonia gas is formed. For example, when an alkali sodium hydroxide reacts with ammonium chloride, it produces sodium chloride and ammonia gas.
NH4Cl(aq) + NaOH(aq) NaCl(aq) + NH3(g) + H2O(1)
- No. v. Identify the colors of the precipitates formed by reaction of caustic soda with; copper, zinc and ferric salts.
Answer. When caustic soda NaOH reacts with copper salt it gives blue precipitates of cupric hydroxide.
CuS04(aq) + 2NaOH(aq) Cu(OH)2(8)+ Na2SO4(aq)
When caustic soda reacts with zinc salt, it gives white precipitates of zinc hydroxide.
ZnCl2(aq) + 2NaOH(aq) Zn(OH)2 (s) + 2NaCl(aq)
When caustic soda reacts with ferric salt, it gives brown precipitates of ferric hydroxide.
FeCl3 (aq) + 3NaOH(aq) Fe(OH)3 (s) + 3NaCl(aq)