Explain why solid sodium oxide is a non-conductor of electricity.

Molten sodium oxide is a good conductor of electricity. State the half-equation for the reaction occurring at the positive electrode during the electrolysis of molten sodium oxide.

State the acid-base nature of sodium oxide.

State the equation for the reaction of sodium oxide with water.

in the solid state ions are in fixed positions/there are no moveable ions / OWTTE;

Do not accept answer that refers to atoms or molecules.

\({\text{2}}{{\text{O}}^{2 - }} \to {{\text{O}}_2} + {\text{4}}{{\text{e}}^ - }/{{\text{O}}^{2 - }} \to \frac{1}{2}{{\text{O}}_2} + {\text{2}}{{\text{e}}^ - }\);

Accept e instead of e^–.

basic;

Allow alkaline

\({\text{N}}{{\text{a}}_2}{\text{O}} + {{\text{H}}_2}{\text{O}} \to {\text{2NaOH}}/{\text{N}}{{\text{a}}_2}{\text{O}} + {{\text{H}}_2}{\text{O}} \to {\text{2N}}{{\text{a}}^ + } + {\text{2O}}{{\text{H}}^ - }\);

Do not accept \( \rightleftharpoons \)

This was expected to be a high-scoring question but this was not found in practice. In Part (a) there were many references to delocalised/mobile electrons and also molecules and atoms. It did not appear that the structural properties of ionic substances are well understood.

There were many attempts in (b) which involved the sodium ion rather than the oxide and those who chose oxide often had difficulty in producing a balanced equation.

The best answered part of this question was Part (c) though a significant percentage described it as a weak base.

The best answered part of this question was Part (c) though a significant percentage described it as a weak base.