Question

3. Identify the following substances :

(i) An alkaline gas A which gives dense white fumes with hydrogen chloride.

Answer 1

Step 1: The gas which gives dense white fumes with Hydrogen chloride HCl is Ammonia gas ${\mathrm{NH}}_3$. Following inferences can be made in this experiment:

1. Ammonia gas is alkaline due to the basicity of the nitrogen atom.
2. The dense fumes observed are of white Ammonium chloride ${\mathrm{NH}}_4\mathrm{Cl}$.
3. This test is used in the detection of Nitrogen present in a compound.

Step 2: Chemical reaction:

$$\begin{gathered} {\mathrm{NH}}_4\mathrm{OH}\left(\mathrm{l}\right)+\mathrm{HCl}\left(\mathrm{aq}\right)\to {\mathrm{NH}}_4\mathrm{Cl}\left(\mathrm{aq}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \\ \mathrm{Ammonium}\mathrm{Hydrogen}\mathrm{Ammonium} \\ \mathrm{Hydroxide}\mathrm{Chloride}\mathrm{Chloride} \end{gathered}$$

Final Answer: Hence, the gas is Ammonia.