Question

Calculate the ratio of effusion rates of C12 to F2

Answer 1

Note: I assume you meant $C{l_2}$ , not $C12$ .

From the kinetic theory we know that effusion rate of component $i$ is proportional to it's molar mass (it's known as Graham's Law)

$${Q_i} \sim \frac{1}{{\sqrt {{M_i}} }}$$

Thus

$$\frac{{{Q_{C{l_2}}}}}{{{Q_{{F_2}}}}} = \sqrt {\frac{{{M_{{F_2}}}}}{{{M_{C{l_2}}}}}} = \sqrt {\frac{{{M_F}}}{{{M_{Cl}}}}} = \sqrt {\frac{{18.998[\frac{{\text{g}}}{{{\text{mol}}}}]}}{{35.446[\frac{{\text{g}}}{{{\text{mol}}}}]}}} \approx 0.732$$