A gas of unknown identity diffuses at a rate of 83.3 mL/s in a diffusion apparatus in which carbon dioxide diffuses at the rate of 102 mL/s. Calculate the molecular mass of the unknown gas.
Recall: Graham's Law of Effusion allows us to compare the rate of effusion of two gases. Graham's Law states that the rate of effusion of a gas is inversely proportional to its molar mass.
This means that when comparing two gases:
Let's designate CO2 as gas 1 and the unknown as gas 2. We're given:
rateCO2 = 102 mL/s MCO2 = 12.01 g/mol C + 2(16.00 g/mol O) = 44.01 g/mol
rateunk = 83.3 mL/s Munk = ?