Question

At a certain temperature and $2$ atm pressure, equilibrium constant ($K_p$) is $25$ for the reaction: ${SO}_2\left(g\right)+{NO}_2\left(g\right)\rightleftharpoons {SO}_3\left(g\right)+NO\left(g\right)$.
Initially, if we take $2$ moles each of the four gases and $2$ moles of inert gas, what would be the equilibrium partial pressure of ${NO}_2$?

• A. $1.33$ atm
• B. $0.1665$ atm
• C. $0.133$ atm
• D. None of the above

Answer 1

The correct option is C $0.133$ atm

For the reaction:
${SO}_2\left(g\right)+{NO}_2\left(g\right)\rightleftharpoons {SO}_3\left(g\right)+NO\left(g\right)$
At eqm. 2-x 2-x 2+x 2+x

So, $K_p=\frac{(2+x{)}^2}{(2-x{)}^2}=25$ or, $x=\mathrm{1.33.}$

Partial pressure of $N{O}_2=\frac{2-x}{10}\times P_t=\frac{0.67\times 2}{10}=0.133atm.$