GRAHAM'S LAW OF EFFUSION (p. 387 in text book)

* compares the rates of effusion of different gases

* lighter gases (lower molar masses) effuse faster than heavier gases (higher molar masses)

rate A  =         MM B
rate B              MM A            

the rate of gas A compared to the rate of gas B is equal to the square root of the inverse of the molar masses of the gases

EXAMPLE 1:  Compare the rates of effusion for oxygen gas and hydrogen gas.



EXAMPLE 2:  An unknown gas effuses 1.18 times faster than SO2.  What is the molar mass of the unknown gas?



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