Question

At ${27}^{\circ }$C it was observed during a reaction of hydrogenation that the pressure of hydrogen gas decreases from 2 atm to 1.1 atm in 75 minutes. The rate of reaction is:

• A. $8.13\times {10}^{-6}M{s}^{-1}$
• B. $3.24\times {10}^{-6}M{s}^{-1}$
• C. $7.32\times {10}^{-6}M{s}^{-1}$
• D. $7.43\times {10}^{-6}M{s}^{-1}$

Answer 1

Answer: (A)

$8.13\times {10}^{-6}M{s}^{-1}$

The ideal gas equation is $PV=nRT$ or $P=CRT$.

2 atm corresponds to $\frac{2}{0.082\times 300}=8.13\times {10}^{-2}M$

1.1 atm corresponds to $\frac{1.1}{0.082\times 300}=4.47\times {10}^{-2}M$

Thus $\Delta C=8.13\times {10}^{-2}-4.47\times {10}^{-2}=3.66\times {10}^{-2}M$

$△t=75min=75\times 60sec=4500sec$

The average rate of the reaction is, $rate=\frac{\Delta C}{\Delta t}=\frac{3.66\times {10}^{-2}M}{4500sec}=8.13\times {10}^{-6}Mse{c}^{-1}$.