Question

If CO and NH3 are allowed to effuse through a porous membrane under identical conditions, the rate of effusion for NH3 will be ________ times that of CO .

a) 0.61

B) 1.3

C) 0.78

d) 1.6

Answer 1

The rate of effusion or diffusion is inversely proportional to the square root of molar mass of the

gases.

Therefore, the ratio is given as follows:

\(\begin{aligned} \frac{r_{C O}}{r_{N H_{3}}} &=\sqrt{\frac{M_{N H_{3}}}{M_{C O}}} \\ &=\sqrt{\frac{17 \mathrm{~g} / \mathrm{mol}}{28 \mathrm{~g} / \mathrm{mol}}} \\ \frac{r_{C O}}{r_{N H_{3}}} &=0.78 \\ r_{M H_{3}} &=1.3 r_{\mathrm{CO}} \end{aligned}\)

Hence, the correct answer is (b). That is, the rate of effusion for \(N H_{3}\) is 1.3 times that of \(C O\) .