Chem. Equilibrium Post Assessment 2 #29

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DesireBrown1J
Posts: 98
Joined: Wed Sep 18, 2019 12:18 am

Chem. Equilibrium Post Assessment 2 #29

Postby DesireBrown1J » Thu Jan 23, 2020 9:05 pm

A researcher fills a 1.00 L reaction vessel with 1.84 x 10-4 mol of BrCl gas and heats it to 500 K. At equilibrium, only 18.3 % of the BrCl gas remains. Calculate the equilibrium constant, assuming the following reaction is taking place.
2BrCl(g) ⇌ Br2 (g) + Cl2(g)

A. 19.5
B. 8.39 x 10-5
C. 4.98
D. 1.68 x 10-4

How exactly do I go about solving a problem like this? I did these steps, then I was lost.

1.84 x 10-4 - (18.3/100) = 3.36 x 10-5 *remaining of BrCl
1.84 x 10-4-3.36 x 10-5=1.5 x 10-4 *used up in reaction

Connie Chen 1E
Posts: 51
Joined: Mon Jun 17, 2019 7:24 am

Re: Chem. Equilibrium Post Assessment 2 #29

Postby Connie Chen 1E » Thu Jan 23, 2020 10:03 pm

You could use an ICE table to solve this problem.

You know that the equilibrium concentration of BrCl is 3.36 x 10-5. You also know that the change from its initial concentration is -2x. We also know that 1.5 x 10-4 was used up (change in concentration). So 1.5 x 10-4 = -2x.

From this, we can get the x value. Since the initial concentrations of Br2 and Cl2 are 0 and their changes in concentration are +x, we can then find their equilibrium concentrations.

We now know the equilibrium concentrations of all three molecules, so we can use this to find the K value.


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