Question

The reaction $A\left(g\right)+2B\left(g\right)\to C\left(g\right)$ 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 rate is :

• A. $\frac{1}{12}$
• B. $\frac{1}{50}$
• C. $\frac{1}{25}$
• D. none

Answer 1

The correct option is C $\frac{1}{25}$

$A_{\left(g\right)}+2B_{\left(g\right)}\to C_{\left(g\right)}$

Initial $0.41.00$

$0.4-x1.0-x0.3$

$r_i\propto P_A{P}_B^2$

$r_i=k{P}_A{P}_B^2$

$=k\left(0.4\right){\left(1.0\right)}^2=0.4$

$r_t=k{P}_A{P}_B^2=k(0.4-x){(1-2x)}^{2}x=0.3atm$

$r_t=k\left(0.1\right){\left(0.4\right)}^2$

$=0.016$

$\therefore r_t=0.016=\frac{0.4}{25}=\frac{1}{25}$ of initial