Question

A mixture of $S{O}_3.S{O}_2$ and $O_2$ gases is maintained at equilibrium in 10 litre flask at a temperature at which $K_c$ for the reaction,$2S{O}_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2S{O}_3\left(g\right)$ is 100 $mo{l}^{-1}litre$ At equilibrium.
a) If no. of mole of $S{O}_3$ and $S{O}_2$ in flask are same, how many mole of $O_2$ are present?
b) If no. of mole of $S{O}_3$ in flask are twice the no.of mole of $S{O}_2$. how many mole of $O_2$ are present?

Answer 1

Volume of flask $=10$ litre

(a) ${2SO}_2+O_2\rightleftharpoons {2SO}_{3}K=100$

At $a$ $x$ $a$

eqd $a/10$ $x/10$ $a/10$

const

$K_C=\frac{{\left(a/10\right)}^2}{\left(x/10\right){\left(a/10\right)}^2}=100$

$\frac{1}{100}=\frac{x}{10}\Rightarrow x=1/10$

0.1 moles of $O_2$ are present .

(b) ${2SO}_2+O_2\rightleftharpoons {2SO}_3$

At $a$ $x$ $2a$

eq $a/10$ $x/10$ $2a/10$

conc

$K_C=\frac{{\left(\frac{2a}{10}\right)}^2}{\left(x/10\right){\left(a/10\right)}^2}\Rightarrow \frac{4}{x/10}=100$

$x=4/10=0.4$ moles of $O_2$.