How many SCSA Chemistry questions cover Oxidation and reduction?

AusGrader has 141 SCSA Chemistry questions on Oxidation and reduction, all with instant AI grading and detailed marking feedback.

SCSA (WACE) Chemistry — Oxidation and reduction Questions & Answers | AusGrader

Q19

2020

SCSA

1 mark

Q19

1 mark

The following half-equations show some predicted standard reduction potentials for seaborgium (Sg) oxides:

$2 \text{ SgO}_3\text{(s)} + 2 \text{ H}^+\text{(aq)} + 2 \text{ e}^- \rightarrow \text{Sg}_2\text{O}_5\text{(s)} + \text{H}_2\text{O}(\ell) \quad \text{E}^0 = -0.046 \text{ V}$

$\text{Sg}_2\text{O}_5\text{(s)} + 2 \text{ H}^+\text{(aq)} + 2 \text{ e}^- \rightarrow 2 \text{ SgO}_2\text{(s)} + \text{H}_2\text{O}(\ell) \quad \text{E}^0 = +0.11 \text{ V}$

$\text{SgO}_2\text{(s)} + 4 \text{ H}^+\text{(aq)} + \text{ e}^- \rightarrow \text{Sg}^{3+}\text{(aq)} + 2 \text{ H}_2\text{O}(\ell) \quad \text{E}^0 = -1.34 \text{ V}$

The strongest reducing agent is

A

$\text{SgO}_3$

B

$\text{Sg}_2\text{O}_5$

C

$\text{SgO}_2$

D

$\text{Sg}^{3+}$

Q24

2025

SCSA

1 mark

Q24

1 mark

Which of these two half-cell reactions could be used to design the galvanic cell that generates the largest voltage?

I $PbSO_4(s) + 2 e^- \leftrightharpoons Pb(s) + SO_4^{2-}(aq)$
II $Cr^{3+}(aq) + 3 e^- \leftrightharpoons Cr(s)$
III $Cu^{2+}(aq) + 2 e^- \leftrightharpoons Cu(s)$
IV $Fe^{3+}(aq) + e^- \leftrightharpoons Fe^{2+}(aq)$

A

I and III

B

II and III

C

II and IV

D

III and IV

Q33

2025

SCSA

6 marks

Q33

6 marks

Humans have micro-organisms, such as bacteria in their guts that assist with digestion. One such group of bacteria can convert the lactate ion ( $C_3H_5O_3^-$ ), in the presence of sulfate ions, to the acetate ion, hydrogencarbonate ion and hydrogen sulfide, as represented by the unbalanced equation below:

$C_3H_5O_3^-(aq) + SO_4^{2-}(aq) \rightarrow C_2H_3O_2^-(aq) + HCO_3^-(aq) + H_2S(aq)$

Write balanced half-equations for the oxidation and reduction reactions and a balanced overall redox equation for this reaction.

Oxidation half-equation

Reduction half-equation

Overall redox equation

Oxidation (lactate) half-equation:
$C_3H_5O_3^- + 2 H_2O \rightarrow C_2H_3O_2^- + HCO_3^- + 5 H^+ + 4 e^-$ ( $\times 2$ )

Reduction (sulfate) half-equation:
$SO_4^{2-} + 10 H^+ + 8 e^- \rightarrow H_2S + 4 H_2O$

Overall redox equation:
$2 C_3H_5O_3^- + SO_4^{2-} \rightarrow 2 C_2H_3O_2^- + 2 HCO_3^- + H_2S$

Marking Criteria

Descriptor	Marks
Correctly identifies the oxidation and reduction half-equations	1
Oxidation half-equation: Correct species	1
Oxidation half-equation: Correctly balanced	1
Reduction half-equation: Correct species	1
Reduction half-equation: Correctly balanced	1
Overall redox equation: Correctly balanced	1

Q27

2024

SCSA

12 marks

Q27

Write balanced ionic equations for any reactions between the following substances and state any observations before and after mixing.

If there is no reaction, write 'no reaction' for the equation and if there is no change observed write 'no visible reaction'. Use the colours stated in the Data booklet if required.

Q27a

4 marks

A magnesium strip is added to excess dilute hydrochloric acid solution.

Equation:

Mg(s) + 2 H^+(aq) \rightarrow Mg^{2+}(aq) + H_2(g)

Observations
-grey/silver solid added to a colourless solution

effervescence and solid dissolves/disappears

Marking Criteria

Descriptor	Marks
Equation: Correct species	1
Equation: Correct balancing	1
Observations: grey/silver solid added to a colourless solution	1
Observations: effervescence and solid dissolves/disappears	1

Q27b

4 marks

A few drops of bromine liquid are added to a potassium iodide solution.

Equation:

Br_2(l) + 2 I^-(aq) \rightarrow 2 Br^-(aq) + I_2(s)

Observations:

red liquid is added to colourless solution
grey solid precipitates/brown solution formed

Marking Criteria

Equation

Descriptor	Marks
Correct species	1
Correct balancing	1

Observations

Descriptor	Marks
red liquid is added to colourless solution	1
grey solid precipitates/brown solution formed	1

Q27c

4 marks

A piece of aluminium foil is added to a $0.1 \text{ mol L}^{-1}$ nickel(II) nitrate solution.

Equation:

2 Al(s) + 3 Ni^{2+}(aq) \rightarrow 2 Al^{3+}(aq) + 3 Ni(s)

Observations

grey/silver solid is added to green solution/liquid
black/silver solid precipitates and paler green/colourless solution

Marking Criteria

Descriptor	Marks
Equation: Correct species	1
Equation: Correct balancing	1
Observations: grey/silver solid is added to green solution/liquid	1
Observations: black/silver solid precipitates and paler green/colourless solution	1

Q26

2025

SCSA

10 marks

Q26

Write balanced equations for any reactions between the following sets of substances and describe the expected observations of the reaction.

Show only those species that are involved in the reaction; include all state symbols.
Include a description of the reactants and products.
If there is no reaction, write ‘no reaction’.
If there is no change observed write ‘no observable reaction’.

Q26a

5 marks

A strip of copper metal is added to a sealed flask containing chlorine gas.

Equation

Expected observations

Equation:
$Cu(s) + Cl_2(g) \rightarrow CuCl_2(s)$

Observation:
Reactants – salmon pink solid and greenish-yellow gas
Products – green solid forms on solid and greenish-yellow gas decolourises

Marking Criteria

Descriptor	Marks
Correct species	1
Correctly balanced	1
State symbols	1
states the observation: Reactants – salmon pink solid and greenish-yellow gas	1
states the observation: Products – green solid forms on solid and greenish-yellow gas decolourises	1

Q26b

5 marks

Combustion of octane gas in limited oxygen gas.

Equation

Expected observations

Equation:
$2 C_8H_{18}(g) + 17 O_2(g) \rightarrow 16 CO(g) + 18 H_2O(g)$

Observation:
heat evolved/temperature increases/(orange) flame
Any one of the following (to match equation):

black solid/soot formed
colourless gases mixed

Marking Criteria

Descriptor	Marks
Correct species	1
Correctly balanced	1
State symbols	1
states the observation: heat evolved/temperature increases/(orange) flame	1
states the observation: Any one of the following (to match equation): black solid/soot formed OR colourless gases mixed	1

SCSA Chemistry Oxidation and reduction

Equation

Observations

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