1 (a) 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

The half-equation for the production of chlorine, 2Cl⁻ → Cl₂ + 2e⁻, indicates oxidation as it illustrates the loss of electrons by chloride ions. In this process, two chloride ions each lose one electron, resulting in the formation of a chlorine molecule.

The solution remaining at the end of the electrolysis is alkaline because hydroxide ions (OH⁻) are produced when water is also electrolysed. This increase in hydroxide ions results in a basic (alkaline) solution.

To obtain metallic sodium from the electrolysis of sodium chloride solution, I would change the electrolyte to molten sodium chloride instead of the aqueous solution. This would allow sodium ions to be reduced at the cathode to form metallic sodium.

Oxygen is formed at the anode during the electrolysis of copper sulfate solution when water molecules lose electrons. The hydroxide ions (OH⁻) in the solution lose electrons, resulting in the formation of oxygen gas and water.

To calculate the number of moles of copper produced, we use the formula:

Number of moles = [ \frac{\text{mass}}{\text{molar mass}} = \frac{1.27 , ext{g}}{63.5 , \text{g/mol}} = 0.02 , \text{mol} ]

Therefore, the number of moles of copper produced is 0.02 mol.