The electrolysis of carbon dioxide gas, CO₂, in water is one way of making ethanol, C₂H₅OH - VCE - SSCE Chemistry - Question 2 - 2020 - Paper 1
Question 2
The electrolysis of carbon dioxide gas, CO₂, in water is one way of making ethanol, C₂H₅OH.
The diagram below shows a CO₂–H₂O electrolysis cell. The electrolyte use... show full transcript
Worked Solution & Example Answer:The electrolysis of carbon dioxide gas, CO₂, in water is one way of making ethanol, C₂H₅OH - VCE - SSCE Chemistry - Question 2 - 2020 - Paper 1
Step 1
Identify the Cu–Zn electrode as either the anode or the cathode in the box provided in the diagram above.
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Answer
The Cu–Zn electrode acts as the cathode. In electrolysis, the cathode is where reduction occurs, and in this cell, it is where CO₂ is being converted to ethanol.
Step 2
Determine the applied voltage required for the electrolysis cell to operate.
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Answer
The applied voltage must be greater than 0.73 V to facilitate electrolysis. This value is derived from the standard electrode potentials and accounts for the necessary overpotential to ensure the reaction proceeds.
Step 3
Write the balanced equation for the overall electrolysis reaction.
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Answer
The balanced equation for the overall electrolysis reaction is:
[ 2CO₂ + 3H₂O → C₂H₅OH + 3O₂ ]
