Chemistry 0620 · IGCSE · Electrolysis

Electrolysis — practice question

Sodium is made by electrolysis.
(a)[1]

Explain why sodium is obtained by electrolysis rather than by reduction with carbon.

(b(i))[1]

The anode must be inert. Suggest a substance suitable for use as the anode.

(b(ii))[1]

Label the anode on the diagram.

(b(iii))[1]

Using the diagram, describe how you can tell that sodium is less dense than molten sodium chloride.

(c)[4]

During electrolysis of concentrated aqueous sodium chloride, gases form at both electrodes. State the names of the products and describe what you would see at each electrode.

(d)[2]

Give two ways in which sodium's physical properties are unlike those of transition elements.

(e(i))[1]

The symbol equation for making sodium hydride is shown. 2Na + H2 -> 2NaH Write this reaction as a word equation.

(e(ii))[1]

Suggest why the hydrogen has to be dry.

(e(iii))[1]

Sodium hydride reduces iron(III) oxide to iron. Fe2O3 + 3NaH -> 2Fe + 3NaOH Explain how this equation shows that iron(III) oxide is reduced.

(f)[1]

State the flame-test colour seen for sodium.

Worked solution & mark scheme

This 14-mark question has a full step-by-step worked solution and mark scheme. One marking point: sodium is too reactive / too high in the electrochemical series / carbon extraction would need an excessively high temperature

  • Full mark scheme, point by point
  • Step-by-step worked solution
  • Write your answer & get it marked instantly by AI