Unit 7: Equilibrium
Chemistry · Unit 7 · Paper 3

Equilibrium unit test

A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.

Paper 1Paper 2Paper 3
Each paper is built from this unit’s 17 terms and is the same for everyone, so a teacher can assign “Unit 7, Paper 3” and every student sits the identical test. Multiple choice is marked objectively; the written sections you mark yourself against the model answer and rubric.
Suggested time 37 min 34 points0/17 attempted
1

Effect of volume change

2

Le Châtelier's principle

3

Solubility product Ksp

4

ICE table

5

Reaction quotient Q

6

Common ion effect

7

Equilibrium constant K

8

Magnitude of K

9

Small-x approximation

10

Kc and Kp relationship

11

Effect of a catalyst on equilibrium

12

Effect of temperature on K

Short answer 1. Define or explain: pH effect on solubility

3 pts

Short answer 2. Define or explain: Dynamic equilibrium

3 pts

Short answer 3. Define or explain: Q vs K reasoning on a graph

3 pts

Short answer 4. Define or explain: Adding an inert gas at constant volume

3 pts

Free response

10 pts

At 500 K, 1.00 mol of PCl₅ is placed in an evacuated rigid 2.00 L flask and allowed to reach equilibrium: PCl₅(g) ⇌ PCl₃(g) + Cl₂(g). At equilibrium, [Cl₂] = 0.150 M. (a) Construct an ICE table and determine the equilibrium concentration of each species. (b) Calculate Kc at 500 K. (c) Calculate Kp at 500 K, given Kp = Kc(RT)^Δn with R = 0.08206 L·atm·mol⁻¹·K⁻¹. (d) Predict and justify the effect on the equilibrium amount of PCl₃ if the flask volume is doubled at constant temperature. (e) Explain why the volume change in part (d) does not alter the value of Kc.