How many NESA Chemistry questions cover Factors that Affect Equilibrium?

AusGrader has 71 NESA Chemistry questions on Factors that Affect Equilibrium, all with instant AI grading and detailed marking feedback.

NESA (HSC) Chemistry — Factors that Affect Equilibrium Questions & Answers | AusGrader

Q12

2023

NESA

1 mark

Q12

1 mark

The industrial production of ammonia is represented by the Haber process reaction shown.

\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \quad \quad \Delta H = -91.8 \text{ kJ mol}^{-1}

Factors such as temperature and pressure need to be considered in order to maximise yield.

Which of the following is correct?

A

A lower pressure would result in a higher yield.

B

A higher pressure would result in a higher yield.

C

A lower temperature would result in a lower yield.

D

A higher temperature would result in a higher yield.

Q7

2024

NESA

1 mark

Q7

1 mark

The following equilibrium was established in a container.

2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g) \quad \Delta H = -198 \text{ kJ mol}^{-1}

Which of the following would increase the yield of $\text{SO}_3(g)$ ?

A

Increasing the volume

B

Increasing the temperature

C

Removing the product as it is formed

D

Keeping temperature and volume constant

Q23

2024

NESA

3 marks

Q23

3 marks

Consider the following equilibrium system.

[\text{Co(H}_2\text{O)}_6]^{2+}(aq) + 4\text{Cl}^-(aq) \rightleftharpoons [\text{CoCl}_4]^{2-}(aq) + 6\text{H}_2\text{O}(l)

$[\text{Co(H}_2\text{O)}_6]^{2+}(aq)$ is pink and $[\text{CoCl}_4]^{2-}(aq)$ is blue. When a solution of these ions and chloride ions is heated, the mixture becomes more blue.

Relate the observed colour change to the change in $K_{eq}$ .

The mixture becomes more blue as temperature is increased, which suggests that the concentration of $[\text{CoCl}_4]^{2-}$ is increasing. This means that an increase in temperature favours the forward reaction. This response will result in a larger value of $K_{eq}$ as

K_{eq} = \frac{[[\text{CoCl}_4]^{2-}]}{[[\text{Co}(\text{H}_2\text{O})_6]^{2+}][\text{Cl}^-]^4}

Marking Criteria

Descriptor	Marks
Provides a sound relationship between the observed colour change and $K_{eq}$	3
Provides some information about changes in concentration of reactants and/or products	2
Provides some relevant information	1
None of the above	0

Q29

2025

NESA

4 marks

Q29

4 marks

Consider the following reaction.

2\text{NO}_2(g) \rightleftharpoons \text{N}_2\text{O}_4(g) \quad \Delta H = -57.2 \text{ kJ mol}^{-1}

A sealed reaction vessel of fixed volume contains a mixture of $\text{NO}_2$ and $\text{N}_2\text{O}_4$ gases at equilibrium.

Explain the impact of the addition of argon, an inert gas, on the temperature of the system.

Addition of argon gas does not change the amount of NO $_2$ or N $_2$ O $_4$ present. As the volume of the system remains consistent, the concentrations of NO $_2$ and N $_2$ O $_4$ are unchanged. Therefore $Q = K_{eq}$ and the system remains at equilibrium. Accordingly, the temperature remains constant.

Marking Criteria

Descriptor	Marks
Provides a thorough explanation of the impact on the temperature of this system	4
Provides an explanation that shows a sound understanding of equilibrium systems	3
Provides a description of an impact on the system	2
Provides some relevant information	1
None of the above	0

Q30

2025

NESA

5 marks

Q30

Phosgene is used in industry as a starting material to synthesise useful polymers. Phosgene ( $\text{Cl}_2\text{CO}$ ) is a gas at room temperature and is highly toxic.

Q30a

2 marks

Justify a suitable precaution when using phosgene.

Phosgene is dangerous to the environment because it is toxic. Therefore, it is important to ensure it does not leak from the reaction vessel, which requires constant monitoring.

Marking Criteria

Descriptor	Marks
Justifies a named precaution	2
Provides any relevant information	1
None of the above	0

Q30b

3 marks

Phosgene is synthesised by the reaction of carbon monoxide (CO) and chlorine ( $\text{Cl}_2$ ) in the gas phase.

\text{Cl}_2(g) + \text{CO}(g) \rightleftharpoons \text{Cl}_2\text{CO}(g)

Explain why an excess of carbon monoxide and a catalyst are used in the industrial synthesis of phosgene.

The use of a catalyst saves time and money because it increases the rate of reaction by lowering the activation energy. The use of a large excess of CO causes the equilibrium to shift to the products side, therefore improving the yield of phosgene.

Marking Criteria

Descriptor	Marks
Explains the use of a catalyst AND Explains the use of a large excess of CO	3
Describes how BOTH features affect the reaction but does NOT link cause and effect OR Explains how one feature affects the reaction	2
Provides any relevant information	1
None of the above	0

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