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

1 Answer
Jul 10, 2017

molar mass of A=37 g/mol

Explanation:

We can use Graham's law of effusion to solve this:

rArB=MBMA

where

  • rArB is a number representing the ratio of effusion rates of gas A to gas B, in this case 0.68:1=0.68

  • MA and M2 are the molar masses of gases A and B, respectively.

We know the molar mass of gas B is 17 g/mol, so let's solve this for MA:

0.68=17lg/molMB

MB=17lg/mol0.68

MB=(17lg/mol0.68)2=37 g/mol

rounded to 2 significant figures.