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?
We can use Graham's law of effusion to solve this:
#(r_A)/(r_B)#is a number representing the ratio of effusion rates of gas A to gas B, in this case #0.68:1 = 0.68#
#M_A#and #M_2#are the molar masses of gases A and B, respectively.
We know the molar mass of gas B is