Question

Consider the reaction $2S{O}_2\left(g\right)+O_2\left(g\right)\rightleftharpoons 2S{O}_3\left(g\right)$ for which $K_c=278M^{-1}$. 0.001 mole of each of the reagents $S{O}_2\left(g\right)$, $O_2\left(g\right)$ and $S{O}_3\left(g\right)$ are mixed in a 1.0 L flask. Determine the reaction quotient of the system and spontaneous direction of the system.

• A. $Q_c=1000$; the equilibrium shifts to the right
• B. $Q_c=1000$; the equilibrium shifts to the left
• C. $Q_c=0.001$; the equilibrium shifts to the left
• D. $Q_c=0.001$; the equilibrium shifts to the right

Answer 1

Answer: (B)

$Q_c=1000$; the equilibrium shifts to the left

${2SO}_2\left(g\right)+O_2\left(g\right)\rightleftharpoons {2SO}_3\left(g\right)$

$Q=\frac{[S{O}_3{]}^2}{\left[S{O}_2{]}^2\right[O_2]}$

$Q=\frac{(0.001{)}^2}{\left(0.001{)}^2\right(0.001)}$

$Q=\frac{1}{0.001}$

$Q_c=1000$

$Q_c>K_c$

Thus, reaction shifts in backward direction i.e. towards left.