The ions in sodium chloride solution are
sodium ions, Na⁺
chloride ions, Cl⁻
hydrogen ions, H⁺
hydroxide ions, OH⁻
Sodium chloride solution is electrolysed using a direct electric current - Edexcel - GCSE Chemistry - Question 1 - 2013 - Paper 1
Question 1
The ions in sodium chloride solution are
sodium ions, Na⁺
chloride ions, Cl⁻
hydrogen ions, H⁺
hydroxide ions, OH⁻
Sodium chloride solution is electrolyse... show full transcript
Worked Solution & Example Answer:The ions in sodium chloride solution are
sodium ions, Na⁺
chloride ions, Cl⁻
hydrogen ions, H⁺
hydroxide ions, OH⁻
Sodium chloride solution is electrolysed using a direct electric current - Edexcel - GCSE Chemistry - Question 1 - 2013 - Paper 1
Step 1
Which of these ions will be attracted to the cathode during the electrolysis of sodium chloride solution?
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Answer
The ions attracted to the cathode are B) H⁺ and Na⁺ ions. The positively charged hydrogen ions migrate towards the cathode where they can gain electrons.
Step 2
Explain how the half-equation shows that chloride ions are oxidised.
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Answer
In the half-equation 2Cl⁻ → Cl₂ + 2e⁻, chloride ions (Cl⁻) lose electrons during the reaction. This loss of electrons indicates that the chloride ions are being oxidised, as oxidation is defined as the process of losing electrons.
Step 3
Suggest why the solution remaining at the end of the electrolysis is alkaline.
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Answer
The solution becomes alkaline due to the formation of hydroxide ions (OH⁻) during the electrolysis process. These hydroxide ions increase the pH of the solution.
Step 4
State what change you would make to the electrolyte to obtain metallic sodium.
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Answer
To produce metallic sodium, the electrolyte would need to be changed to a molten state, allowing the sodium ions to move freely and be reduced at the cathode.
Step 5
Explain how the oxygen is formed from ions in the solution.
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Answer
When copper sulfate solution is electrolysed, water molecules are oxidised at the anode. The half-equation for this reaction is 2H₂O → O₂ + 4H⁺ + 4e⁻, which shows that oxygen gas is released, while hydrogen ions are produced.
Step 6
Calculate the number of moles of copper, Cu, produced in this experiment.
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Answer
To calculate the number of moles of copper produced, we use the formula:
extMoles=relative atomic massmass
Plugging in the values:
Moles=63.51.27≈0.02
Thus, the number of moles of copper produced is approximately 0.02.