11.89 HW

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Yiling Liu 1N
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Joined: Sat Jul 09, 2016 3:00 am

11.89 HW

Postby Yiling Liu 1N » Tue Nov 15, 2016 12:32 am

The problem is: "The following plot shows how the partial pressures of reactant and products vary with time for the decomposition of compound A into compounds B and C. All three compounds are gases. Use this plot to do the following: (a) Write a balanced chemical equation for the reaction. (b) Calculate the equilibrium constant for the reaction. "

(Plot is given in the textbook.)


I am having difficulty writing the balanced chemical equation based on the plot. The answer key reads that 2 moles of A decompose into 1 mole of B and 2 moles of C, but I was wondering how to get to that step.


The calculations in the answer key mostly make sense to me here. However, I'm unsure why the answers divided each partial pressure by 100?

ie the answer key wrote k = (5/100)(10/100)^2 / [ (18/100)^2 ]

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Re: 11.89 HW

Postby Chem_Mod » Fri Nov 18, 2016 8:17 pm

a) The partial pressure of A drops by about 10 kPa while the pressures of B and C increase by about 5 and 10 kPa, so this gives the 2:1:2 ratio.

b) Kp is written with units of bar (100 kPa, abt 1 atm), so the equilibrium partial pressures are each divided by 100 to convert to the right units.

nikita bhat 2D
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Re: 11.89 HW

Postby nikita bhat 2D » Fri Nov 18, 2016 10:59 pm

To add on to the previous response,
we know that A is a reactant because the graph shows a decreasing trend
we know that B and C are products because their graphs have an increase in partial pressure.

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