Reaction Rates 
[Aug. 19th, 201104:08 pm]
Chemistry Help

Hey, I was wondering if anyone could help me with a problem regarding reaction rates
For the following reaction in a 4.00L container, it was found that 1.00 x 10^{4} mol of C_{4}H_{8} reacted over a time period from 10:58 A.M. to 11:15 A.M.
C_{4}H_{8} (g) > 2C_{2}H_{4} (g)
What is the average rate, in M/s, for this reaction?
I took the time period of 10:5811:15, which is 17 minutes, and did dimensional analysis to figure out what it was in seconds (1020 s). I set the equation up as
1.00 x 10^{4} M  1020 s
and got 9.8 x 10^{8} but the answer is 2.5 x 10^{8}. I don't know what I'm doing wrong.
Thank you to anyone that can help! 

