A gas is produced when conc. H_2SO_4 is added to solid sodium chloride taken in a test tube. The gas coming out of the delivery tube is passed over a dry blue litmus paper and then over a moist blue litmus paper. What would you observe ? Explain reason with the help of a chemical equation.

A gas is produced when conc. H_2SO_4 is added to solid sodium chloride

1.	A gas is produced when conc. H_2SO_4 is added to solid sodium chloride taken in a test tube. The gas coming out of the delivery tube is passed over a dry blue litmus paper and then over a moist blue litmus paper. What would you observe ? Explain reason with the help of a chemical equation.
Answer» Solution :HCl gas is produced when conc. `H_2SO_4`is added to solid sodium chloride. `NaCl + H_2SO_4 toNaHSO_4 + HCl` HCl gas when passed over dry blue litmus paper shows no effect. HCl gas when passed over MOIST blue litmus paper TURNS it RED. This is because dry HCl gas does not produce `H^+`ions, therefore there is no action on dry blue litmus paper. Moist blue litmus paper contains water. HCl gas when passed over moist blue litmus paper reacts with water to FORM `H^+` ions. An acid (containing `H^+`ions) turns blue litmus red. Therefore,a red colour will be obtained.