Question

A vessel at $1000\text{K}$ contains carbon dioxide with a pressure of $0.4\text{atm}$. Some of the carbon dioxide is converted to carbon monoxide on addition of graphite. Calculate the value of K if the total pressure at equilibrium is $0.7\text{atm}$

• A. $3.6\text{atm}$
• B. $6\text{atm}$
• C. $3\text{atm}$
• D. $5\text{atm}$

Answer 1

The correct option is A $3.6\text{atm}$

$C{O}_2\text{(g)}+C\text{(s)}\rightleftharpoons 2CO\text{(g)}$
Suppose decrease in pressure of $C{O}_2$ after reaction = $x\text{atm}$
$\text{Final pressure}=0.7$
$\text{Then increase in pressure due to}CO=2x$
$\text{Final pressure}=(0.4-x)+2x=0.4+x=0.7\text{atm}$
$\therefore x=0.3\text{atm}$
Hence, ${\text{P}}_{C{O}_2}=0.4-0.3=0.1\text{atm}$
${\text{P}}_{CO}=2\times 0.3=0.6\text{atm}$
$K=\frac{{\text{P}}_{CO}^2}{{\text{P}}_{C{O}_2}}=\frac{{0.6}^2}{0.1}=3.6\text{atm}$