Question

The reaction$A\left(g\right)+2B\left(g\right)\to C\left(g\right)+D\left(g\right)$ is an elementary process. In an experiment, the initial partial pressure of A & B are $P_A$ = 0.6 atm and $P_B$ = 0.8 atm. The ratio of rate of reaction relative to initial rate when $P_c$ becomes 0.2 atm:

• A. $1:6$
• B. $1:5$
• C. $1:3$
• D. $2:5$

Answer 1

The correct option is A $1:6$

Since this is elementary reaction

$Rateofreation=K{P}_A{P}_B^2$

PA PB PC PD

Initial 0.6 0.8 0 0

Final 0.4 0.4 0.2 0.2

$\Rightarrow Initialrate=K\left(0.6\right)(0.8{)}^2$.............(1)

$\Rightarrow Finalrate=K\left(0.4\right)(0.4{)}^2$ ...............(2)

On dividing equation 2 by equation 1

Thus, $Ratio=\frac{0.4\times {0.4}^2}{0.6\times {0.8}^2}=\frac{1}{6}$

Thus (a) is the correct answer.