A water insoluble calcium compound (A) on reacting with dil. H2SO4 released a colourless and
odourless gas (B) with brisk effervescence. When gas (B) is passed through lime water, limewater turns milky and again formed compound A. Identify A and B and write the chemicalequations for the reactions involved.Carbon dioxide is the gas which turns lime water milky when passed through it. Also, lime water turns milky due to the formation of calcium carbonate which is insoluble in water. Hence the compound A is calcium carbonate and B is carbon dioxide gas. Following is the chemical equation for the reaction of calcium sulphate and dilute sulphuric acid
CaCO3 + H2SO4 → CaSO4 + H2O + CO2
The equation for reaction of lime water and carbon dioxide gas is as follows
Ca(OH)2 + CO2 → CaCO3 + H2O