Question

For a reaction $A_{\left(g\right)}\to B_{\left(g\right)}+C_{\left(g\right)}$, the rate constant for the reaction is $3\times {10}^{-3}{M}^{-}mi{n}^{-1}$. At what concentration of A will at the rate of reaction be $2\times {10}^{-3}$ M min.

• A. $1$M
• B. $0.52$M
• C. $0.82$ M
• D. $\frac{2}{3}$M

Answer 1

Answer: (C)

$0.82$ M

Rate constant= $3\times {10}^{-3}{M}^{-1}mi{n}^{-1}$

Unit of rate constant determine the order of reaction, so it will be $2^{nd}$ order reaction.

Rate of reaction= Rate constant $[A{]}^2$

$\Rightarrow 2\times {10}^{-3}=3\times {10}^{-3}[A{]}^2$

$\Rightarrow \left[A\right]=\sqrt{\frac{2}{3}}=0.82M$