AP Chemistry : Calculating the Equilibrium Concentrations

Study concepts, example questions & explanations for AP Chemistry

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Example Questions

Example Question #1 : Calculating The Equilibrium Concentrations

Consider formation of Nitrogen monoxide:   with .  If the initial concentration of N2 was 0.085M and O2 was 0.038 M, what is the concentration of nitrogen monoxide at equilibrium?

Possible Answers:

1.2 x 10-6 M

1.1 x 10-4  M

1.2 x 10-5 M

1.1 x 10-3 M

3.2 x 10-8 M

Correct answer:

1.2 x 10-5 M

Explanation:

01

Example Question #1 : Calculating The Equilibrium Concentrations

Given the ICE table below, what are the signs on the terms that would appear in the “Change” row?

02

Possible Answers:

-x, -2x, +x

 +x, +4x, -x

-x, -x, +x

+x, +x, +x

+x, +2x, +x

Correct answer:

-x, -2x, +x

Explanation:

Based on the balanced equation, one would use -x, -2x, and +x.

Example Question #3 : Calculating The Equilibrium Concentrations

Find the equilibrium concentrations for C in the following chemical reaction:  A + B -> 2C

03

K = 9.0 x 10-8

Possible Answers:

1.1 M

1.5 x 10-4 M

1.2 x 10-2 M

3.0 x 10-3 M

0.12 M

Correct answer:

1.5 x 10-4 M

Explanation:

03b

Example Question #4 : Calculating The Equilibrium Concentrations

What is the equilibrium concentration for A- in the following reaction if the starting concentration of HA is 0.60 M?

         

Possible Answers:

1.2 M

3.5 x 10-3 M

2.3 x 10-3 M

1.2 x 10-5 M

2.3 x 10-4 M

Correct answer:

3.5 x 10-3 M

Explanation:

04

Example Question #5 : Calculating The Equilibrium Concentrations

What is the equilibrium concentration for A- in the following reaction if the starting concentration of HA is 0.30 M?

          

Possible Answers:

2.1 M

 3.9 x 10-5 M

1.5 x 10-4 M

1.5 x 10-3 M

2.1 x 10-3 M

Correct answer:

 3.9 x 10-5 M

Explanation:

05

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