## Textbook HW problem #47b

Shannon Han 2B
Posts: 48
Joined: Fri Sep 26, 2014 2:02 pm

### Textbook HW problem #47b

I calculated that 0.019 M was the initial amount of PCl5 and then the equilibrium concentration was 0.009 and this was correct with the solutions manual. Then, in part b of this problem, it asks what percentage of the PCl5 has decomposed at equilibrium and the solutions does 0.010/0.019 * 100. I thought it would be 0.009/0.019 *100 since it asks for the percentage decomposition of PCl5, not of PCl3, which has the equilibrium concentration of 0.010 M.

Astred 1D
Posts: 15
Joined: Fri Sep 26, 2014 2:02 pm

### Re: Textbook HW problem #47b

Hi,

In the problem when you look for the % of PCl5 decomposed you have your initial amount of .019M and at equilibrium its concentration is .009. So to find the amount decomposed you do .019M-.009M= .0100M. You then find the % by decomposed amount/original amount x 100% and your answer should come out to 53%.