ICE Chart for HW problem 11.49 6th Edition

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KarlaArevalo2F
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ICE Chart for HW problem 11.49 6th Edition

Postby KarlaArevalo2F » Wed Jan 09, 2019 11:37 pm

How would one understand to complete an ICE chart for problem 11.49? I have gotten the initial for NH3 but how would we know what steps to follow after? (First time seeing ICE charts :( )

Kate Chow 4H
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Re: ICE Chart for HW problem 11.49 6th Edition

Postby Kate Chow 4H » Thu Jan 10, 2019 2:05 pm

Since you know that NH4HS is a solid, you can put 0 in for the whole column. You can add "x" to both NH3 and H2S in the change row (C) because you eventually want to find their equilibrium concentrations. You're given Kc so you can use the equilibrium equation: Kc=[NH3][H2S]. Kc=[0.2+x][x]. Solve for x using the quadratic formula and you have your answer!

NH4HS ---> NH3 + H2S
I 0, .4mol/2L, 0

C 0, +x, +x

E 0, 0.2M+x, +x

Hope this helps! (the formatting got weird when I posted, but hopefully you can still understand the ice table)

KarlaArevalo2F
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Re: ICE Chart for HW problem 11.49 6th Edition

Postby KarlaArevalo2F » Thu Jan 10, 2019 7:57 pm

thank you for your explanation! My point of confusion is using the quadratic formula in the chart. May you please explain..

Vincent Li 4L
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Re: ICE Chart for HW problem 11.49 6th Edition

Postby Vincent Li 4L » Thu Jan 10, 2019 8:13 pm

In this case, you would use the quadratic equation on what Kate pointed out to be the equilibrium constant expression, Kc = [0.2 + x][x]. Since you have one variable, x, and there is no other way to properly factor it, once you expand out the Kc expression, you use the quadratic formula x = (-b ± √(b^2 - 4ac))/(2a). Solving for x will give you two possible answers, so be sure to eliminate any that are either negative (not possible to have negative partial pressure or concentrations) or any that exceed the initial values.

KarlaArevalo2F
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Re: ICE Chart for HW problem 11.49 6th Edition

Postby KarlaArevalo2F » Thu Jan 10, 2019 8:19 pm

Thank you both!


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