Explain why solid ionic compounds cannot be electrolysed, but they can be electrolysed when molten. Select one option:

• In solid form, electrons are locked in place, but in molten form, electrons are free to flow through the liquid.
• In solid form, ions are held in a fixed lattice and cannot move, but in molten form, the ions are free to move to the electrodes.
• In solid form, molecules can only vibrate, but in molten form, atoms can easily share protons between electrodes.

The table below shows the products of the electrolysis of some molten ionic compounds. Complete the missing entries.

Vanadium is extracted by electrolysing molten vanadium(V) oxide. Balance the equation for this reaction by choosing coefficients from the list: 2, 3, 4, 5.

$2V_2{O}_5\to \_\_\_V+\_\_\_O_2$

Calculate the relative formula mass ($M_r$) of vanadium(V) oxide ($V_2{O}_5$). Relative atomic masses ($A_r$): $O=16$, $V=51$.

The list below shows part of the reactivity series of metals, including the non-metal carbon.

Draw on this

Metals can be extracted from their compounds by:

• electrolysis
• reduction with carbon.

Electrolysis is more expensive than reduction with carbon. Predict one metal from the list that would be extracted by each method.

• Extracted by electrolysis:
• Extracted by carbon reduction: