Question

The reaction $A\left(g\right)+B\left(g\right)⟶C\left(g\right)$ is an elementary reaction. In an experiment involving this reaction, the initial partial pressures of $A$ and $B$ are $P_A=0.40$ atm and $P_B=1.0$ atm respectively. When $P_C=0.3$ atm, the rate of the reaction relative to the initial is:

• A. $\frac{1}{12}$
• B. $\frac{1}{50}$
• C. $\frac{1}{4}$
• D. none of these

Answer 1

The correct option is D none of these

The initial rate $r_0=k{P}_A^0{P}_B^0$
The initial rate $r_0=k\times 0.40\times 1.0=0.40k$.....(1)
When $P_C=0.3$ atm, $P_A=0.40-0.30=0.10$ atm and $P_B=1.0-0.3=0.7$ atm.
The rate $r=k{P}_A^0{P}_B^0$
The rate $=k\times 0.10\times 0.7=0.07k$.....(2)
Divide equation (2) with equation (1)

$\frac{r}{r_0}=\frac{0.07k}{0.40k}$

$\frac{r}{r_0}=\frac{0.7}{4}$

Hence, the option (D) none of these is the correct answer.