1)Draw a labelled diagram to show the preparation of hydrogen chloride gas in laboratory
2) test the gas evolved first with dry and then with wet litmus paper..
In which cases does the litmus paper show change in colour
3) state the reason of exhibiting acidic character by dry hcl gas /hcl solution
WILL I LOSE MARK IF I DIDN'T MENTION CONCENTRATED SPECIFICALLY?? VERY URGENT!!!!!!! PLSSS
Answers
Explanation:
Always remember that any acid or base will produce ions when it is dissolved in the water.
Laboratory preparation and litmus paper test of hydrogen chloride gas :
1) Hydrogen chloride gas is prepared in the laboratory by reacting sodium chloride salt with concentrated sulphuric acid at a temperature below 200°C.
• The above reaction can be represented as under :
2NaCl + conc. H₂SO₄ + ∆ (200°C) → Na₂SO₄ + 2HCl
• The reason for choosing NaCl over other metal chlorides is that it is very cheap and readily available in the market.
2) When the HCl gas evolved in the reaction is treated with a wet blue litmus paper, the colour of the paper changes from blue to red, showing that the HCl solution is acidic in nature.
• However, no change in colour of litmus paper is observed when the paper is kept dry, showing that dry HCl gas is neutral in nature.
3) The reason behind HCl solution exhibiting acidic character is that when HCl is dissolved in water, it dissociates into H+ ions, imparting an acidic character to the solution.
NOTE - No need to worry ! You would not lose much marks for not specifying H₂SO₄ as concentrated, a half mark may be. Henceforth, please be careful towards mentioning the conditions of reactants, as they are very important for a reaction to take place.
