Gas A effuses 0.68 times as fast as Gas B. If the molar mass of Gas B is 17 g, what is the mass of Gas A?

1 Answer
May 23, 2017

37g

Explanation:

We can use Graham's law of effusion , which relates the relative rates of effusion of gases in terms of their molar masses:

r1r2=MM2MM1

Where
r1r2 is the ratio of effusion of gas 1 to gas 2, and
MM1,2 is the molar mass of the gases 1 and 2, respectively.

We're given that the ratio of effusion of gas A to gas B is 0.68, and that MMB is 17gmol, so

0.68=17MMA

MMA=(170.68)2=37gmol

The mass of the gas is thus 37g.