Question

Iron filling and water were placed in a 5 litre vessel and sealed. The tank was heated to ${1000}^{0}C$. Upon analysis the tank was found to contain 1.1 g of hydrogen and 42.5 g of water vapour. If the reaction in the tank is represented by
3Fe(s) + $4H_2{O}_{\left(g\right)}$ $\rightleftharpoons F{e}_3{O}_4\left(s\right)+4H_2\left(g\right)$,
The value of equilibrium constant, $K_c$ is:

• A. 30
• B. 0.03
• C. 3
• D. 0.003

Answer 1

The correct option is D 0.003

Given, $3Fe\left(s\right)+4H_{2}O\rightleftharpoons {Fe}_3{O}_4\left(s\right)+4H_2\left(g\right)$

$K_c=\frac{{\left[H_2\right]}^4}{{\left[H_{2}O\right]}^4}$

Concentration of $H_2$ = $\frac{\text{No. of moles}}{Volume}=\frac{\frac{1.1}{2}}{5L}=0.11$

Concentration of $H_{2}O$ = $\frac{\text{No. of moles}}{Volume}=\frac{\frac{42.5}{18}}{5L}=0.472$

$⟹K_c={\left(\frac{0.11}{0.472}\right)}^4=0.003$