Question

The degree of dissociation of $N_2{O}_4\rightleftharpoons 2N{O}_2$ is $\alpha$. If initial $N_2{O}_4\left(g\right)$ is one mole, the total number of moles at equilibrium is:

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

Answer 1

The correct option is C $1+\alpha$

$N_2{O}_4\rightleftharpoons 2N{O}_2$
initial moles $1$ $0$
equilibrium moles $1-\alpha$ $2\alpha$

Total number of moles $=$ moles of $N_2{O}_4$ + moles of $N{O}_2$
$=1-\alpha +2\alpha$

Total number of moles at equilibrium $=1+$ $\alpha$

Hence, option C is correct.