A student carries out the electrolysis of a 1.0 M solution of sodium chloride using graphite electrodes - VCE - SSCE Chemistry - Question 5 - 2004 - Paper 1
Question 5
A student carries out the electrolysis of a 1.0 M solution of sodium chloride using graphite electrodes. The setup for this experiment is shown below.
1.0 M NaCl(aq... show full transcript
Worked Solution & Example Answer:A student carries out the electrolysis of a 1.0 M solution of sodium chloride using graphite electrodes - VCE - SSCE Chemistry - Question 5 - 2004 - Paper 1
Step 1
a. Write an equation for the half reaction that occurs at the cathode.
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Answer
At the cathode during the electrolysis of sodium chloride, the reduction of water occurs, producing hydrogen gas. The half-reaction can be represented as:
2H2O+2e−→H2(g)+2OH−
Step 2
b. i. Equation for half reaction that produces gas 1.
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Answer
At the anode, one of the reactions produces chlorine gas. The equation for the half-reaction producing chlorine gas is:
2Cl−→Cl2(g)+2e−
Step 3
b. ii. Equation for half reaction that produces gas 2.
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The second reaction at the anode involves the oxidation of water, producing oxygen gas and releasing electrons. The corresponding half-reaction is:
2H2O→O2(g)+4e−+4H+
Step 4
c. i. What difference, if any, would you expect in the product or products formed at the cathode?
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Answer
At a higher concentration (approximately 6 M) of sodium chloride, the products at the cathode would still primarily consist of hydrogen gas; however, the enhanced ionic strength might slightly increase the efficiency of hydrogen production due to reduced resistance.
Step 5
c. ii. What difference, if any, would you expect in the product or products formed at the anode?
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Answer
At this increased concentration, the production of chlorine gas at the anode would remain the same, but the efficiency may improve due to more abundant chloride ions. Therefore, we expect no major change in products, still yielding chlorine gas.
