Question

The degree of dissociation is $0.4$ at $400$K and $1$ atm for the gaseous reaction $2HI\left(g\right)\to H_2\left(g\right)+I_2\left(g\right)$. Assume ideal behaviour of all the gases, calculate the density (in gm/litre) of mixture at $400$ K and $1$ atm [At. wt. of Iodine = $127$ ; Use R = $0.08$ atm-litre/K-mole].

Answer 1

$2HI\left(g\right)\rightleftharpoons H_2\left(g\right)+I_2\left(g\right)$

$2n(1-\alpha )$ $n\alpha$ $n\alpha$

$PV=2nRT$

$\Rightarrow P=2.\frac{W}{MV}RT$

$\Rightarrow P=\frac{2d}{M}RT$

$\Rightarrow d=\frac{1atm\times (1+127)gm/mol}{2\times 0.08atm-lit/K-mol\times 400K}$

$=2gm/litre$