Question

The gaseous reaction $A \, \left(g\right) \rightarrow 2B\left(g\right)+C\left(g\right)$ is found to be first order with respect to $A$ . If the reaction is started with $P_{A}=90 \, torr$ the pressure after $10 \, min$ is found to be $180 \, torr$ . The rate constant of the reaction is

• A. $1.15 \times 10^{- 3} \, \text{s}^{- 1}$
• B. $2.30 \, \times \, 10^{- 3} \, s^{- 1}$
• C. $3.45 \, \times \, 10^{- 3} \, s^{- 1}$
• D. $4.60 \, \times \, 10^{- 3 \, }s^{- 1}$

Answer 1

Answer: (A)

$A\left(g\right) \rightarrow \, 2B\left(g\right)+C \, \left(g\right)$
$\left((P\right)_{0}- \, p) \, 2p \, \, p$
$P_{total}=P_{0}+2p=180 \, torr$
$p=45 \, torr$
$\text{k} = \frac{1}{\text{t}} ln \frac{90}{45} = 1.15 \times 10^{- 3} \, \text{s}^{- 1}$