Question

At equilibrium total number of moles for the reaction $2HI\rightleftharpoons H_2+I_2$, if $\alpha$ is degree of dissociation, are

• A. $2$
• B. $2-\alpha$
• C. $1$
• D. $1-\alpha$

Answer 1

Answer: (A)

	$HI$	$\rightleftharpoons +H_2$	$I_2$
Initial moles	$2$	$0$	$0$
Change	$-\alpha$	$\frac{\alpha }{2}$	$\frac{\alpha }{2}$
moles at equilibrium	$2-\alpha$	$\frac{\alpha }{2}$	$\frac{\alpha }{2}$

The reaction is $2HI\rightleftharpoons H_2+I_2$.
$\alpha$ is the degree of dissociation.
Total number of moles $=2-\alpha +\frac{a}{2}+\frac{a}{2}=2$.