Textbook HW problem #47b

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

Textbook HW problem #47b

Postby Shannon Han 2B » Fri Nov 21, 2014 10:22 pm

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

Postby Astred 1D » Sat Nov 22, 2014 12:24 am

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%.


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