This question is about silver chloride.
Define the term enthalpy of lattice formation.
Some enthalpy change data are shown in the table below:
| Process | Enthalpy change / kJ mol−1\text{kJ mol}^{-1}kJ mol−1 |
|---|---|
| AgCl(s)→Ag+(aq)+Cl−(aq)\text{AgCl(s)} \rightarrow \text{Ag}^+\text{(aq)} + \text{Cl}^-\text{(aq)}AgCl(s)→Ag+(aq)+Cl−(aq) | +66+66+66 |
| Ag+(g)→Ag+(aq)\text{Ag}^+\text{(g)} \rightarrow \text{Ag}^+\text{(aq)}Ag+(g)→Ag+(aq) | −464-464−464 |
| Cl−(g)→Cl−(aq)\text{Cl}^-\text{(g)} \rightarrow \text{Cl}^-\text{(aq)}Cl−(g)→Cl−(aq) | −364-364−364 |
Use these data to calculate the enthalpy of lattice formation of silver chloride.
A calculation of the enthalpy of lattice formation of silver chloride based on a perfect ionic model gives a smaller numerical value (a less negative value) than the experimentally derived value in Part 2. Explain this difference.
Identify a reagent that could be used to indicate the presence of chloride ions in an aqueous solution, and describe the observation made.
27 exam-style questions on AQA A Level Chemistry Thermodynamics (A-level only), covering Born–Haber cycles (A-level only) and Gibbs free-energy change, $\Delta G$ , and entropy change, $\Delta S$ (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.