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Grade 12 - Equilibria

Total questions: 15

Worksheet time: 14mins

Name
Class
Date
1.

The equilibrium constant, Kc, for the reaction to form ethyl ethanoate from ethanol and ethanoic acid,

C2H5OH + CH3CO2H → CH3CO2C2H5 + H2O,


at 60oC is 4.00.


When 1.00 mol each of ethanol and ethanoic acid are allowed to reach equilibrium at 60oC, what is the number of moles of ethyl ethanoate formed?

a)

13\frac{1}{3}

b)

23\frac{2}{3}

c)

14\frac{1}{4}

d)

34\frac{3}{4}

2.

Which of the following could act as buffer solutions?

a)

NaHCO3 and Na2CO3

b)

CH3CO2H and NaCl

c)

HNO3 and NaNO3

d)

Ba(OH)2 and BaCl2

3.

Which of the following can act as a Bronsted-Lowry acid?

a)

H3O+

b)

OH-

c)

CH3COO-

d)

NH2-

4.

The pH of a 1.0 mol dm-3 solution of a weak monobasic acid is 4. What is the dissociation constant of the weak acid?

a)

1.0 x 10-2 mol dm-3

b)

1.0 x 10-4 mol dm-3

c)

1.0 x 10-7 mol dm-3

d)

1.0 x 10-8 mol dm-3

5.

An acidified solution containing 0.10 mol dm-3 of zinc sulphate and 0.10 mol dm-3 of copper(II) sulphate is saturated with hydrogen sulphide at 15oC. The concentration of S2-(aq) in the solution is then 10-35 mol dm-3.


The solubility product of zinc sulphide at 15oC is 10-24 mol2 dm-6 and of copper(II) sulphide is 10-40 mol2 dm-6.


Which statement describes what happens in the solution?

a)

No precipitate is formed

b)

Copper(II) sulphide only is precipitated

c)

Copper(II) sulphide is precipitated first, followed by zinc sulphide

d)

Zinc sulphide is precipitated first, followed by copper(II) sulphide

6.

Stomach juices have a pH of 1.0. aspirin is a monobasic acid represented by HA (Ka = 10-4 mol dm-3) which dissociation into ions H+ and A-. What are the relative concentrations of H+, A- and HA when aspirin from a tablet enters the stomach?

a)

[H+] > [HA] > [A-]

b)

[HA] > [H+] = [A-]

c)

[H+] > [A-] > [HA]

d)

[H+] = [A-] > [HA]

7.

Which one of the following acid solution can be used to give an effective buffer solution at a pH < 7 by partial neutralization with aqueous NaOH?

a)

0.01 mol dm-3 CH3CO2H

b)

0.1 mol dm-3 HI

c)

0.01 mol dm-3 HCl

d)

0.1 mol dm-3 HNO3

8.

Which statement explains the observation that magnesium hydroxide dissolves in aqueous ammonium chloride, but not in aqueous sodium chloride?

a)

ionic radius of the NH4+ ion is similar to that of Mg2+ but not that of Na+

b)

NH4Cl dissociates less fully than NaCl.

c)

The ions Na+ and Mg2+ are isoelectronic (have the same number of electrons).

d)

The ion NH4+ acts as an acid.

9.

Why is ethanoic acid a stronger acid in liquid ammonia than in its aqueous solution

a)

ammonia is a stronger base than water

b)

ammonium ethanoate is completely ionized in aqueous solution

c)

ammonium ethanoate is strongly acidic in aqueous solution

d)

liquid ammonia is a more polar solvent than water

10.

Which of the following shows the correct dissolution reaction for BaCl2?

a)
b)
c)
d)
11.

Given that the molar solubility of Sn(OH)2 is "s".

The correct mathematical expression for solubility product constant of Sn(OH)2 is:

a)

2s2 = Ksp

b)

2s3 = Ksp

c)

4s3 = Ksp

d)

8s3 = Ksp

12.

Precipitation of silver chloride , AgCl will occur when

a)

Qsp = Ksp

b)

Qsp > Ksp

c)

Qsp < Ksp

13.
Define chemical equilibrium.
a)
A reaction is reversible.
b)
The concentration of the reactants is equal to the concentration of the products.
c)
The rate of a forward reaction is equal to the rate of the reverse reaction.
d)
The reaction stops and no further change in concentration occurs.
14.
2SO2(g)+O2(g)⇌2SO3(g)
Removing O2(g) will
a)
shift equilibrium right
b)
shift equilibrium left
c)
increase pressure
d)
have no change
15.

Changes in pressure in equilibrium reaction will only affect substances that are in the __________ state.

a)

gaseous

b)

liquid

c)

solid

d)

plasma