Electrolytic Processes Practice Questions

Which one of the following is an electrolyte?

• A solid potassium bromide
• B molten potassium bromide
• C copper wire
• D liquid hexane

Explain why solid potassium bromide does not conduct electricity.

Give the name of each of the labelled parts X, Y and Z.

State what is meant by the term electrolysis.

Three ionic compounds are melted and then electrolysed using inert electrodes.

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

molten compound	product at the cathode	product at the anode
lead bromide	lead
magnesium chloride		chlorine
sodium iodide

Describe what would be seen on the cathode during this electrolysis.

Write the half equation for the reaction at the cathode.

Chlorine is formed at the anode. Write the half equation for this reaction.

Give one reason why graphite is a suitable material for the electrodes.

Name the gas formed at the cathode and explain why sodium metal is not formed.

Write the half equation for the reaction at the anode.

Name the compound left in the solution at the end of the electrolysis.

Explain, in terms of electrons, why the reaction at the cathode is a reduction.

State the type of reaction taking place at the anode and justify your answer.

Write the balanced equation for the overall reaction that occurs when molten calcium chloride is electrolysed.

Describe the method the student should use, after cleaning the electrodes with emery paper.

Explain why the cathode must be washed and dried before it is weighed at the end.

State how the mass of the anode changes during this electrolysis.

Name the product formed at the cathode.

Describe what is seen at the anode.

Explain the movement of the lead ions and the bromide ions in the molten lead bromide during the electrolysis.

Give one reason why this demonstration is carried out in a fume cupboard.

Write the half equation for the reaction at the anode.

Write the half equation for the reaction at the cathode.

Explain how this process produces copper that is much purer than the copper used as the anode.

Explain why the concentration of the copper sulfate solution stays almost the same during the electrolysis.

Identify the anomalous result and explain how you know that it is anomalous.

Suggest one reason why this result is higher than expected.

Use the results, ignoring the anomaly, to calculate the mass of copper that would be gained by the cathode in $30$ minutes.

State the conclusion that can be drawn from these results about the mass of copper deposited at the cathode.

Explain why the sulfuric acid is added to the water.

Oxygen is formed at the anode from hydroxide ions, $\mathrm{OH^-}$. Write the half equation for this reaction.

The volume of hydrogen collected is twice the volume of oxygen collected in the same time. Explain why.

Sodium sulfate solution gives the same two gases when it is electrolysed with inert electrodes. Explain why.