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ICSE Class 9 Chemistry Question 19 of 55

ICSE Questions Set in Previous Years — Question 19

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Question 19

In each case, describe one chemical test applied to the following substances, which would enable you to distinguish between them : carbon dioxide gas and hydrogen chloride gas

Answer

Carbon dioxide gas — It turns lime water milky due to the formation of white ppt. of calcium carbonate. The milkiness disappears when carbon dioxide is passed in excess.

Ca(OH)2 + CO2 ⟶ CaCO3↓ + H2O

CaCO3↓ + H2O + CO2 [excess] ⟶ Ca(HCO3)2 [soluble]

Hydrogen chloride gas — When a glass rod dipped in ammonia solution is brought near the gas, dense white fumes of ammonium chloride are released.

NH3 + HCl ⟶ NH4Cl