Question

An unknown gas effuses 1.66 times more rapidly than CO2. What is the molar mass of the unknown gas, given that the molar mass of CO2 is 44 grams?

Answer 1

the molar mass is 16.0 grams 

Answer 2

To determine the molar mass of the unknown gas, we use Graham's Law of effusion which relates the rate of the gases with their respective molar masses. We calculate as follows:

r1 / r2 = √(M2 / M1 )

We let 1 represent the unknown gas and 2 the carbon dioxide.

r1 / r2 = 1.66 = √(44.01 / M1 )
M1 = 15.97 g/mol