Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can describe the three factors in dissolving a salt: breaking up the solid, reorganising the solvent, and ion–solvent attractions. (Guide: “Three factors at the particle level”)
- I can give the sign of the enthalpy and entropy contribution of each factor. (Guide: table; Practice Q1)
- I can explain why small or highly charged ions tend to make ΔS° of dissolving less positive or negative. (Guide: Worked example 2; Practice Q6)
- I can link the sign of ΔG° of dissolution to the size of K_sp. (Guide: “Dissolving as a thermodynamic process”; Practice Q3)
Calculation
- I can calculate ΔG° of dissolution from ΔH° and ΔS°, keeping kJ and J consistent. (Guide: Worked example 1; Practice Q2)
- I can convert between ΔG° of dissolution and K_sp in either direction. (Practice Q3, Q4)
- I can find ΔS° of dissolution from K_sp and ΔH°. (Practice Q4)
- I can predict, with a calculation, how K_sp changes with temperature for endothermic and exothermic dissolving. (Guide: “Temperature and solubility”; Practice Q6)
Reasoning
- I can explain how a salt can dissolve even though dissolving is endothermic. (Guide: Worked example 3; Practice Q7)
- I can explain how a salt can be sparingly soluble even though dissolving is exothermic. (Guide: Worked example 2; Practice Q6, Q7)
- I can explain why cancelling terms make the total free energy of dissolution hard to predict. (Guide: “Why predictions are hard”; Practice Q5)
- I can evaluate how well an enthalpy-only model describes the solubility of a salt. (Guide: Worked example 3; Practice Q7)
All ticked? Move on to Topic 9.7, Coupled Reactions, or return to the course roadmap.