Electrolysis Practice Questions

What is meant by the term electrolyte?

Solid lithium chloride does not conduct electricity.

Molten lithium chloride does conduct electricity.

Explain why.

Magnesium chloride contains $\mathrm{Mg^{2+}}$ ions and $\mathrm{Cl^{-}}$ ions.

State which electrode each type of ion moves to when the power supply is switched on.

Give a reason for your answer.

Name the product formed at each electrode.

Negative electrode ______________

Positive electrode ______________

Explain why potassium is extracted by electrolysis and not by reduction with carbon.

Extracting potassium by electrolysis uses large amounts of energy.

Give two reasons why.

Complete the table to show the product formed at each electrode.

Explain why sodium is not produced at the negative electrode when sodium sulfate solution is electrolysed.

Complete the half equation for the reaction at the negative electrode.

$\mathrm{Na^{+}} + \underline{\hspace{2cm}} \rightarrow \underline{\hspace{2cm}}$

Complete and balance the half equation for the reaction at the positive electrode.

$\mathrm{Cl^{-}} \rightarrow \underline{\hspace{2cm}} + \underline{\hspace{2cm}}$

State which electrode reaction is an oxidation.

Explain your answer in terms of electrons.

The student used graphite electrodes.

Give one reason why graphite electrodes are used instead of electrodes made from a metal such as copper.

Describe a method the student could use to test the hypothesis using the three solutions.

Name the gas produced at the negative electrode and explain why sodium is not produced.

During the electrolysis the universal indicator around the negative electrode turned purple.

Explain why, in terms of ions.

Explain why cryolite is added to the aluminium oxide.

Explain why the positive electrodes must be replaced regularly.

Write the half equation for the reaction at the negative electrode.

Molten potassium bromide and potassium bromide solution are both electrolysed using inert electrodes.

Compare the electrolysis of molten potassium bromide with the electrolysis of potassium bromide solution.

In your answer you should identify the products at each electrode and explain why they are formed.

Identify the anomalous result and suggest one reason for it.

Use the results to predict the increase in mass of the negative electrode when a current of $1.20\ \mathrm{A}$ is used for 10 minutes.

Explain, in terms of ions and electrons, why a larger current produces a greater increase in the mass of the negative electrode.