What would be the observed vapour density of a completely dissociated () sample of ammonium chloride — Chemical Equilibrium Chemistry Question

💡 Solution & Explanation

$NH_4Cl(g) \rightleftharpoons NH_3(g) + HCl(g)$. Here, 1 mole gives $n=2$ moles of products. For complete dissociation, $\alpha = 1$. Using $\alpha = (D - d) / ((n - 1)d)$, we get $1 = (D - d) / d \Rightarrow d = D/2$. The observed vapour density is exactly half.