Question

A gaseous reaction, $A_2\left(g\right)\to B\left(g\right)+\frac{1}{2}C\left(g\right)$, shows increase in pressure of C from 100 mm to 120 mm in 5 minutes. The rate of disappearance of $A_2$ is:

• A. 4 mm min${}^{-1}$
• B. 8 mm min${}^{-1}$
• C. 16 mm min${}^{-1}$
• D. 2 mm min${}^{-1}$

Answer 1

Answer: (B)

8 mm min${}^{-1}$

$A_2\to B+\frac{1}{2}C$

$\frac{-d\left[A_2\right]}{dt}=\frac{2d\left[C\right]}{dt}$

Thus $\frac{d\left[C\right]}{dt}=\frac{120-100}{5}=4mmmi{n}^{-1}$

$\therefore \frac{-d\left[A_2\right]}{dt}=2\times 4=8mmmi{n}^{-1}$

Hence, option B is correct.