Help with Q 11.7.c (6e)

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He whose name cannot be spoken
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Joined: Sat Apr 28, 2018 3:00 am

Help with Q 11.7.c (6e)

Postby He whose name cannot be spoken » Fri Jan 11, 2019 8:37 am

11.7 The following flasks show the dissociation of a diatomic molecule, X2, over time.
(a) Which flask represents the point in time at which the reaction has reached equilibrium?
(b) What percentage of the X2 molecules have decomposed at equilibrium?
(c) Assuming that the initial pressure of X2 was 0.10 bar, calculate the value of K for the decomposition.

I'm super slumped. According to the solutions, K should be 0.17. I've tried three different things and none of them gave me the expected result.

I'm sure it's super easy and staring me right in the face but I can't figure it out. Help pls?

Chris Freking 2G
Posts: 60
Joined: Fri Sep 28, 2018 12:29 am

Re: Help with Q 11.7.c (6e)

Postby Chris Freking 2G » Fri Jan 11, 2019 9:26 am

In part C, K = (Partial pressure of X)^2 / (Partial Pressure of X2)

Plug in the mole fractions of each molecule (X = 12 molecules/17 molecules) and (X2 = 5 molecules/17 molecules)
Plugging those fractions to K and multiplying by the initial pressure of X2 (0.10 bar) will give the answer 0.17 .

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