9.65 6th edition writing chemical equations






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Helen Zhao 1F
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Joined: Fri Sep 28, 2018 12:20 am

9.65 6th edition writing chemical equations

Postby Helen Zhao 1F » Tue Feb 26, 2019 7:44 pm

For question 9.65 from the 6th edition, how do you know if the compound is decomposing for forming. For example, how do you know its P + 5/2Cl2 -> PCL5 instead of PCl5 -> P + 5/2Cl2?

Andrea Zheng 1H
Posts: 61
Joined: Fri Sep 28, 2018 12:26 am

Re: 9.65 6th edition writing chemical equations

Postby Andrea Zheng 1H » Wed Feb 27, 2019 12:42 am

You can use either the equation for decomposition or composition, as it will yield the same answer.

As an example, part (a):
If you used the equation of composition, P + 5/2Cl2 -> PCl5, you would find that the entropy of the reaction was negative. This means that at higher temperatures, the reverse reaction is favored. This means that P and Cl2 would be favored, showing that at higher temperatures, the compound is less stable.

If you used the equation of decomposition, PCl5 -> P + 5/2Cl2 , you would find that the entropy of the reaction was positive. This means that at higher temperatures, the forward reaction is favored. This means that P and Cl2 would be favored, showing that at higher temperatures, the compound is less stable.

Hope this helps!


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