STUDENT SPACE · TOPIC 4

Brine and copper electrolysis

Explain how concentration and electrode material affect observations.

The essentials

Brine produces hydrogen and chlorine; sodium hydroxide remains in solution.
In CuSO₄(aq) with inert electrodes, Cu²⁺ forms pink-brown copper at the cathode. Oxygen bubbles at the anode.
With copper electrodes in CuSO₄(aq), copper forms at the cathode while the copper anode dissolves.

Try each question before opening its hint or answer. Use paper for calculations and diagrams.

Write the anode equation when the anode is copper.

Need a hint for Question 1?

Draw a simple tally of Cu²⁺ entering and leaving the solution.

Check Question 1

Cu → Cu²⁺ + 2e⁻.

Name the three useful products of brine electrolysis.

Need a hint for Question 2?

Consider both electrode gases and the solution left behind.

Check Question 2

Hydrogen, chlorine and sodium hydroxide solution.

Why does CuSO₄(aq) fade with inert electrodes but not with copper electrodes?

Need a hint for Question 3?

Compare whether the anode can supply replacement copper ions.

Check Question 3

Inert anodes do not replace Cu²⁺. Copper anodes dissolve and replace the Cu²⁺ removed at the cathode.

Use Lesson 4 in your worksheet for written practice. Your teacher will discuss those answers in class.