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ICSE Class 10 Chemistry Question 3 of 22

Solved 2016 Question Paper ICSE Class 10 Chemistry — Question 8

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8
Question

Question 1(d)

State your observations when:

(i) Dilute Hydrochloric acid is added to Lead nitrate solution and the mixture is heated.

(ii) Barium chloride solution is mixed with Sodium Sulphate Solution.

(iii) Concentrated Sulphuric acid is added to Sugar Crystals.

(iv) Dilute Hydrochloric acid is added to Copper carbonate.

(v) Dilute Hydrochloric acid is added to Sodium thiosulphate.

Answer

(i) White precipitate of PbCl2 is formed which is soluble in hot water.
Pb(NO3)2 + 2HCl ⟶ PbCl2 ↓ + 2HNO3

(ii) White coloured precipitate of barium sulphate is formed when sodium sulphate is mixed with barium chloride.
Na2SO4 (dil.) + BaCl2 (aq.) ⟶ 2NaCl + BaSO4 ↓ [white ppt. formed]

(iii) Black spongy charred mass of carbon is formed. Steam is seen to be evolved.

C12H22O11→Conc. H2SO412C [sugar charcoal]+11H2O\text{C}_{12}\text{H}_{22}\text{O}_{11}\xrightarrow{\text{Conc. H}_2\text{SO}_4} \text{12C} \small{\space[sugar\space charcoal]} + \text{11H}_2\text{O}

(iv) Effervescence of CO2 seen which turns lime water milky.
CuCO3 + 2HCl ⟶ CuCl2 + H2O + CO2

(v) Yellow particles of S precipitate.
Na2S2O3 + 2HCl ⟶ 2NaCl + SO2 + S + H2O