Free Printable AP Chemistry Unit 7 Equilibrium

Worksheets

AP Chemistry Unit 7 Equilibrium

Total questions: 20

Worksheet time: 2hrs 46mins

Name

Class

Date

What happens at equilibrium?

The rate of the forward reaction is faster than the rate of the reverse reaction

The rate of the reverse reaction is faster than the rate of the forward reaction

The rates of the forward and reverse reaction are equal

$2NaOH\ +H_2SO_4\ \leftrightarrow\ Na_2SO_4\ +\ 2H_2O$
What is the expression for the equilibrium constant of the above reaction? (Assume all compounds are gases)

$K=\frac{\left[Na_2SO_4\right]\left[H_2O\right]^2}{\left[NaOH\right]^2\left[H_2SO_4\right]}$

$K=\frac{\left[Na_2SO_4\right]\left[H_2O\right]}{\left[NaOH\right]\left[H_2SO_4\right]}$

$K=\frac{\left[NaOH\right]^2\left[H_2SO_4\right]}{\left[Na_2SO_4\right]\left[H_2O\right]^2}$

$K=\frac{\left[NaOH\right]\left[H_2SO_4\right]}{\left[Na_2SO_4\right]\left[H_2O\right]}$

At a particular temperature 10.0 mol NH₃ gas is placed in a 1.0-L container. Over time the NH₃ decomposes to H₂ and N₂:

2NH₃(g) ↔ N₂(g) + 3H₂(g)

At equilibrium the concentration of N₂(g) was found to be 2.4 mol/L. Calculate the value of K for this reaction (using units of mol/L for the concentrations).

K= 3.3

K= 33

K= .030

K= .30

CO(g) + H₂O (g) ↔ CO₂(g) + H₂(g)

Determine the equilibrium concentration for H₂ if the equilibrium concentration of CO₂ was 3.4 mol/L.

3.4 mol/L

6.8 mol/L

2.1 mol/L

1.0 mol/L

A table showing Ksp values for several magnesium compounds is given above. A saturated solution of which of the compounds has the greatest molar concentration of Mg²⁺(aq)?

MgBr₂

MgO

MgF₂

All the compounds have the same molar concentration

If the products are favored in a reaction, what is the value of K?

K<1

K>1

K=1

K=0

The equilibrium constant, K_c, for the following reaction is 23.1 at 300 K.

2Br₂(g) + 2H₂O(g) ↔ 4HBr(aq) + O₂(g)

Assuming that you start with equal concentrations of Br₂ and H₂O and no HBr or O₂ is initially present, describe the relative abundance of Br₂ at equilibrium.

Lower than products

Higher than products

Same as products

Can't tell

HCl(g) + H₂O(g) ↔ Cl^-(aq) + H₃O⁺(aq)

When 0.31 moles of HCl(g) are removed from the equilibrium system at constant temperature, the reaction must

Run in the forward reaction to reestablish equilibrium

Run in the reverse reaction to reestablish equilibrium

Remain the same. It is already at equilibrium.

2SO₂(g) + O₂(g) ↔ 2SO₃(g) K_c= 22

The table lists the initial concentrations of each substance in the system represented by the equation above at a given temperature. Which of the following best predicts what will occur as the system approaches equilibrium?

The rate of the reverse reaction will be greater than the rate of the forward reaction, because K_c< Q_c.

The rate of the forward reaction will be greater than the rate of the reverse reaction, because K_c< Q_c.

The rate of the reverse reaction will be greater than the rate of the forward reaction, because K_{c >} Q_c.

The rate of the forward reaction will be greater than the rate of the reverse reaction, because K_{c >} Q_c.

10.

At what time is equilibrium established in the graph?

2000

4000

6000

8000

11.

CaCO₃(s)⇄ Ca²⁺(aq) + CO₃^2-(aq)

Ksp = 4.3×10^-6 at 298K

The equilibrium in a saturated solution of CaCO₃ is represented above. In an experiment, a student places 6.0g of CaCO₃(s) into 100.0mL of distilled water and stirs the mixture. How would the results be affected if the student repeats the experiment but this time places 6.0g of CaCO₃(s) into 100.0mL of 0.0020M MgCO₃(aq) instead of distilled water?

More solid will dissolve, because the larger value of [CO₃^2-] will cause the equilibrium position to lie farther to the right.

More solid will dissolve, because the smaller value of [CO₃^2-] will cause the equilibrium position to lie farther to the left.

Less solid will dissolve, because the larger value of [CO₃^2-] will cause the equilibrium position to lie farther to the right.

Less solid will dissolve, because the larger value of [CO₃^2-] will cause the equilibrium position to lie farther to the left.

12.

AgCl(s) ⇄ Ag⁺(aq) + Cl^-(aq)

A student prepared a saturated aqueous solution of AgCl and measured its pH. Then the student added a few drops of an unknown solution to the test tube and observed cloudiness in the solutions. On the basis of this information and the equilibrium represented above, which of the following is most likely the identity of the reagent added from the dropper?

Distilled water

KNO₃(aq)

HCl(aq)

NaOH(aq)

13.

NaI(s)⇄Na⁺(aq) + I^-(aq)

Which of the following best explains what the particle diagram is able to show about the entropy change for the dissolution of NaI(s) in pure water?

The particle diagram shows that the dissociation of NaI(s) into ions contributes to an increase in the entropy for the dissolution.

The particle diagram shows that the dissociation of NaI(s) into ions contributes to a decrease in the entropy for the dissolution.

The particle diagram shows that there is no reorganization of the water molecules around the ions and the change in entropy for the dissolution is zero.

The particle diagram shows that there are no interactions between the water molecules and the change in entropy for the dissolution is zero.

14.

Nickel (III) Oxide decomposes to make solid nickel and oxygen gas:

2Ni₂O₃(s)⇄ 4Ni(s) + 3O₂(g)

The above reaction can also be written as:

4Ni(s) + 3O₂(g) ⇄ 2Ni₂O₃(s)

Write the equilibrium constant for the new reaction in terms of K, the equilibrium constant for the original reaction.

K^1/2

1/K

(1/K)^1/2

K²

15.

NH₄I(s) ⇄ NH₃(g) + HI(g)

Write the equilibrium expression for the reaction.

$K=\frac{\left[NH_3\right]\left[HI\right]}{\left[NH_4I\right]}$

$K=\frac{\left[NH_4I\right]}{\left[NH_3\right]\left[HI\right]}$

$K=\left[HI\right]\left[NH_4I\right]$

$K=\left[NH_3\right]\left[HI\right]$

16.

2Na + Cl₂ ⇄ 2NaCl

If the concentration of NaCl is lowered, what must the reaction due in order to achieve equilibrium.

Shift to the left

Shift to the right

Nothing, the reaction is already at equilibrium

17.

If a catalyst is added to a reaction, what will happen to the reaction.

It will always shift to the right

It will always shift to the left

It will not shift at all.

The reaction will slow down.

18.

Cl₂(g) + 2NaBr(s) ⇄ 2NaCl(s) + Br₂(g) K_c=37

If Q_c= 11, which of the following explains whether or not the reaction has reached equilibrium, and why?

The reaction is not at equilibrium because Q_c < K_c; the forward reaction is favored.

The reaction is not at equilibrium because Q_c < K_c; the reverse reaction is favored.

The reaction is at equilibrium because Q_c < K_c.

19.

For which of the following salts would the relationship between molar solubility, s, in mol/L, and the value of K_sp be represented by the equation K_sp= 27s⁴?

KOH

Na₃PO₄

Al₂O₃

MgBr₂

20.

CaI₂(s) ⇄ Ca²⁺(aq) + 2I^-(aq)

K_sp = 3 x 10^-9

What is the mathematical expression that can be used to determine the value of S, the molar solubility of CaI₂(s).

3 x 10^-9= s³

3 x 10^-9= 4s²

3 x 10^-9= 2s²

3 x 10^-9= 4s³

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AP Chemistry Unit 7 Equilibrium

Total questions: 20

Worksheet time: 2hrs 46mins

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