Question

A vessel at 1000 K contains $CO_2$ with a pressure of 0.5 atm. Some of the $CO_2$ is converted into CO on the addition of graphite. It the total pressure at equilibrium is 0.8 atm, the value of K is

• A. 3 atm
• B. 0.3 atm
• C. 0.18 atm
• D. 1.8 atm

Answer 1

Answer: (D)

1.8 atm

Answer 2

$\begin{matrix}&CO_{2}+C& {<=>}&2CO&\\\ \text{Initial }&0.5&&0&&\\\ \text{ Equilibrium}&0.5-x&&2x&&\end{matrix}$ Total pressure at Equilibrium $= 0.8\, atm$ Now $(0.5-x)+2x=0.8\,atm$ $\therefore x=0.8-0.5=0.3$ Pressure of $CO_{2}$ at equilibrium $= 0.5-0.3$ $=0.2\,atm$ Pressure of $CO$ at equilibrium $=2\times0.3=0.6\,atm$ $\therefore K=\frac{\left(pco\right)^{2}}{p_{co_2}}=\frac{\left(0.6\right)^{2}}{0.2}=\frac{0.36}{0.2}=1.8$