Question

water insoluble substance x on reacting with dilute H2 S o4 releases a colourless and odourless gas accompanied by brisk effervescence. when the gas was passed through water the solution obtained turn blue Litmus red .
on bubbling the gas through lime water it initially became milky and the milkiness disappeared by the gas was passed in excess. identify substance X and write the chemical equation.

Answer 1

Sodium carbonate (substance X)on heating with sulphuric acid we get sodium sulphate , CO2 and water

Na2CO3 +H2SO4 ---->Na2SO4 +CO2 +H2O

ON PASSING CO2 gas to lime water it turns milky white due to formation of CaCO3.

Ca(OH)2 +CO2 ---->CaCO3 +H2O

IF EXCESS OF CO2 IS PASSED, the milky white colour disappers due to formation of calciumhydrogen carbonate.

CaCO3+CO2+H2O---->Ca(HCO3)2