Problem 10 in the 1st Chapter 3 Practice Quiz

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104422816
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Joined: Fri Sep 25, 2015 3:00 am

Problem 10 in the 1st Chapter 3 Practice Quiz

Postby 104422816 » Wed Nov 18, 2015 12:25 pm

This question asks tells you that that the equilibrium pressures in a reaction are 1.08 bar for BrCl, 4.9 for Br2, and 7.6 for Cl2. Then it says that half of the brcl is removed from the container and equilibrium is reestablished. what is the new partial pressure?

I have attempted this problem both from an ice table and from the equation pv=nrt and both times I have found that the answer would be 0.54 (half the pressure of 1.08). However the answer is 1. There must be something that I am missing but I can't figure it out. Does anybody have a strategy that could help me?

Sabina Fridman 1D
Posts: 19
Joined: Fri Sep 25, 2015 3:00 am

Re: Problem 10 in the 1st Chapter 3 Practice Quiz

Postby Sabina Fridman 1D » Wed Nov 18, 2015 1:11 pm

The question is asking for the partial pressure of BrCl after the reaction reestablishes equilibrium again. The 0.54 partial pressure that you found is the new pressure of BrCl before the reaction reestablishes equilibrium.

The reaction now will start off again with partial pressures of 0.54 for BrCl, 4.9 for Br2, and 7.6 for Cl2, but since we offset the equilibrium it will now favor the reverse reaction to reestablish equilibrium, so the changes will be opposite of the forward reaction. Because of that I made a new ice table where:

I: 0.54 BrCl 4.9 Br2 7.6 Cl2
C: +2x -x -x

When I worked it out my new pressure of BrCl: 0.54 + 2x, came out to be 1.0.
Hope this kind of makes sense


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