A bottle of ammonia and a bottle of dry hydrogen chloride connected through a long tube are opened s — States of Matter and Gaseous State Chemistry Question

💡 Solution & Explanation

# Formation of Ammonium Chloride Ring **Step 1: Identify the diffusion process** $NH_3$ gas from the ammonia bottle and $HCl$ gas from the hydrogen chloride bottle diffuse through the tube toward each other: $$NH_3 + HCl \rightarrow NH_4Cl \text{(white solid)}$$ **Step 2: Apply Graham's Law of Diffusion** The rate of diffusion is inversely proportional to the square root of molar mass: $$\text{Rate} \propto \frac{1}{\sqrt{M}}$$ - Molar mass of $NH_3$ = 17 g/mol - Molar mass of $HCl$ = 36.5 g/mol Since $M_{HCl} > M_{NH_3}$, ammonia diffuses faster than hydrogen chloride. **Step 3: Determine ring position** The white $NH_4Cl$ ring forms where the two gases meet. Since $NH_3$ travels faster and covers more distance, it will encounter the slower-moving $HCl$ molecules at a point **closer to the HCl bottle** (farther from the ammonia bottle). **Step 4: Conclusion** The white ammonium chloride ring is first formed **nearer to the hydrogen chloride end** of the tube. *Without seeing the options, Option B likely indicates "closer to HCl bottle" or "nearer to the denser gas source"—consistent with the faster diffusion of the lighter ammonia molecule.*