Practice Exam 3
VCE Chemistry | Electrochemistry, Galvanic Cells, Electrolysis, Standard Electrode Potentials
✎ Complete ALL questions on paper before opening the Model Answers lesson. No notes. Aim for 1 minute per mark.
SHORT ANSWER
Question 1 (4 marks)
A galvanic cell is constructed from Ag/Ag⁺ (E°=+0.80 V) and Fe/Fe²⁺ (E°=−0.44 V).
(i) Identify the anode and cathode
(ii) Write the cell reaction
(iii) Calculate the standard EMF.
✎ Write your answer on paper
Question 2 (4 marks)
In an electrolysis experiment, a current of 2.50 A is passed through a CuSO₄ solution for 30.0 minutes.
Calculate the mass of copper deposited (M(Cu)=63.5, F=96485 C/mol).
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Question 3 (4 marks)
Explain the difference between a galvanic cell and an electrolytic cell. Give one practical example of each.
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Question 4 (4 marks)
Use standard electrode potentials to predict whether the following reaction is spontaneous under standard conditions:
Cu(s) + 2H⁺(aq) → Cu²⁺(aq) + H₂(g)
E°(Cu²⁺/Cu)=+0.34 V; E°(H⁺/H₂)=0.00 V
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Question 5 (4 marks)
Describe the Chlor-alkali process. Write half-equations for each electrode and name the three industrial products.
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Question 6 (4 marks)
Calculate the mass of Al (M=27, F=96485) deposited by a current of 50 000 A flowing for 8 hours in the Hall-Héroult process. Al³⁺+3e⁻→Al
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Question 7 (4 marks)
Explain cathodic protection and give two practical examples.
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Question 8 (4 marks)
Write the overall cell equation, anode and cathode half-equations, and calculate the minimum voltage needed to electrolyse water. E°(O₂/H₂O)=+1.23V; E°(H⁺/H₂)=0.00 V.
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EXTENDED RESPONSE
Extended Response 1: Galvanic Cells
Question 9 (2 marks)
Extended Response 1: Galvanic Cells (a)
The following standard electrode potentials are given:
Ag⁺/Ag: +0.80 V; Fe³⁺/Fe²⁺: +0.77 V; I₂/I⁻: +0.54 V; Cu²⁺/Cu: +0.34 V
Using these data, identify the strongest oxidising agent and the strongest reducing agent.
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Extended Response 1: Galvanic Cells
Question 10 (3 marks)
Extended Response 1: Galvanic Cells (b)
Predict whether Fe³⁺ will oxidise I⁻ under standard conditions. Write the cell reaction and calculate E°cell.
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Extended Response 1: Galvanic Cells
Question 11 (4 marks)
Extended Response 1: Galvanic Cells (c)
Describe the structure of a fuel cell that uses hydrogen and oxygen. Write half-equations for each electrode and state the overall reaction.
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Extended Response 2: Electrolysis Calculations
Question 12 (4 marks)
Extended Response 2: Electrolysis Calculations (a)
An electroplating bath deposits silver from AgNO₃ solution. A current of 1.50 A flows for 45 minutes.
Calculate: (i) charge passed, (ii) moles of Ag deposited, (iii) mass of Ag (M=108).
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Extended Response 2: Electrolysis Calculations
Question 13 (3 marks)
Extended Response 2: Electrolysis Calculations (b)
In the same apparatus, a copper object is also immersed. Would the silver deposit uniformly? Explain what factors affect deposit quality in electroplating.
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✓ Finished? Open the next lesson – Model Answers – to mark your work.
