A student tests four unknown substances for electrical conductivity in solid state and when dissolved in water. Substance X conducts when dissolved in water but not when solid. What type of structure and bonding does substance X most likely have?

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Question

A student tests four unknown substances for electrical conductivity in solid state and when dissolved in water. Substance X conducts when dissolved in water but not when solid. What type of structure and bonding does substance X most likely have?

Accepted Answer

Giant ionic lattice with ions held in fixed positions when solid — An ionic compound does not conduct electricity in the solid state because the ions are held in fixed positions in the lattice. When dissolved in water, the lattice breaks down and the ions are free to move, allowing electrical conduction. Metals (A) conduct in both states. Simple molecular substances (B) do not conduct in either state as they have no free ions or electrons. Giant covalent substances (D) do not conduct in either state.

Answer

Giant covalent lattice with strong covalent bonds throughout

Answer

Metallic structure with delocalised electrons throughout

Answer

Simple molecular structure with weak intermolecular forces

Answer

Giant ionic lattice with ions held in fixed positions when solid

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