An unknown gas contains 83% C and 17% H by mass. If effuses at 0.87 times the rate of CO2 gas under the same conditions. What is the molecular formula of the unknown gas?
Well, the rate of effusion is equal to 1/sqrt(m), where m is in amu.
First find CO2 effusion rate, so 1/sqrt(44.011 amu) = 0.150737.
The unknown's effusion rate is 0.87*CO2 effusion rate:
0.87*0.150737 = 0.13114 unknown's rate of effusion
Now find the unknown's total amu.
0.13114 = 1/sqrt(m)
Solve for m = (1/0.13114)^2 = 58.147 amu.
Use percents given:
C = 0.83*58.147 amu = 48.262 amu/12.01 amu = 4.0 C atoms
H = 0.17*58.147 amu = 9.88 amu/1.008 amu = 9.8 Hatoms
Any help is appreciated!