Originally posted by Beagle
The diffusion rate of methane gas compared to that of helium is:
A. twice as fast
B. 4 times as slow
C. 4 times as fast
D. half as fast
E. 12 times as fast
Remember as a gas gets heavier and heavier it makes it more slower overall. So the first thing you should wonder is what is different. Helium is a very light gas. Use common sense and remember all those helium balloons at your 5th birthday party. Then look at methane. It is the most simplest alkane on earth. But it is more complex than helium. Thus, I would eliminate choices A, C, and E immediately. The rest is guessing. I'm sorry I don't know the exact way to solve this solution, but my method gives you a 50/50 shot. Maybe it has to do with molecular weight. Since Helium is a diatomic gas (CH4 (methane is 2x bigger). since you know bigger molecules are slower, then it means that He is twice as fast. But the answer is not A, we are dealing with Methane compared to Helium not the reverse. So we know that methane is twice as slow. The answer is D. Hey, I just solved it by using common sense. Great eh???
Please help! Answer is: D
Anyway, being that it's been 7 years since I took general chem, somebody might want to check up on this because I might be wrong.
