Short Answer 
The procedure involves mixing 1g of sodium chloride with 2ml of concentrated sulfuric acid, producing hydrogen chloride gas. While dry litmus paper shows no color change due to the gas’s anhydrous nature, wet litmus paper turns from blue to red, confirming the gas’s acidic properties when in contact with water.
Step 1: Conducting the Reaction
Begin by adding 1g of solid sodium chloride to 2ml of concentrated sulfuric acid. This combination initiates a chemical reaction that releases hydrogen chloride gas. It’s essential to handle sulfuric acid with care due to its corrosive nature and ensure that the procedure is done in a well-ventilated area.
Step 2: Observing the Gas Reactions
When the hydrogen chloride gas is generated, you will notice that if it comes into contact with dry litmus paper, there is no color change. This happens because the gas is anhydrous and is unable to ionize the litmus dye, thus indicating that it does not exhibit acidic properties in its dry state.
Step 3: Testing with Wet Litmus Paper
To confirm the acidic nature of the evolved gas, use wet litmus paper. When the hydrogen chloride gas interacts with the moisture on the wet litmus paper, it forms hydrochloric acid, causing the paper to turn blue to red. This color change clearly indicates that the gas behaves as a strong acid in the presence of water.