Textbook Problem 5.35

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Jazlyn Romero 1I
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Joined: Wed Sep 30, 2020 10:09 pm

Textbook Problem 5.35

Postby Jazlyn Romero 1I » Mon Jan 11, 2021 10:54 am

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.

Hi! I was having trouble figuring out how to find a balanced chemical equation and calculating the equilibrium constant when just given a graph. Any help would be appreciated, thanks!

Ria Nawathe 1C
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Re: Textbook Problem 5.35

Postby Ria Nawathe 1C » Mon Jan 11, 2021 11:14 am

Hi! For this problem, the first thing you should do is create an ICE table based on the graph. The graph tells you the initial concentrations of A (about 28 M), B (0 M), and C (0 M), and it also shows you the equilibrium concentrations of A (about 18 M), B (5 M), and C (10 M). Based on the difference between the initial and equilibrium concentrations, you can determine the "change" part of the ICE table -- A decreases by 10 M, B increases by 5 M, and C increases by 10 M. The "change" tells you the stoichiometric ratios of A, B, and C -- A and C change by 2 times the value of B. Therefore, the chemical equation is 2A <--> B + 2C. You can then use this equation and the equilibrium concentrations to find Kp for b. Keep in mind though that you need to divide each partial pressure value in the Kp expression by 100 to convert the kPa units to bars.

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