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 state the standard states that the ° in ΔG° refers to: pure solids and liquids, 1 M solutions and gases at 1 bar. (Guide: “What ΔG° means”)
- I can say what ΔG° < 0 and ΔG° > 0 mean for a process, using the phrase “thermodynamically favoured”. (Guide; Practice Q3)
- I can explain why “thermodynamically favoured” is preferred to “spontaneous”, and why ΔG° says nothing about rate. (Guide: “What ΔG° means”; Practice Q4)
- I can explain why an element in its standard state has ΔG°f = 0. (Guide: “Method 1”)
Calculation
- I can calculate ΔG° from free energies of formation, using coefficients and products minus reactants. (Guide: Worked example 1; Practice Q3)
- I can calculate ΔG° from ΔH° and ΔS° at a given temperature, converting J to kJ and °C to K. (Guide: Worked example 2; Practice Q2, Q5)
- I can calculate the temperature at which ΔG° = 0 and say on which side the process is favoured. (Guide: Worked example 2(c); Practice Q5(b), Q7(b))
- I can check a ΔG° answer for a unit slip by judging its size. (Guide: Worked example 2; Practice Q2)
Reasoning
- I can state whether a process is favoured at all, high, low or no temperatures from the signs of ΔH° and ΔS° alone. (Guide: Figure 1; Practice Q1)
- I can justify the sign of ΔS° by describing what happens to the particles. (Practice Q6(a), Q7(a))
- I can explain why freezing water and dissolving sodium nitrate need both enthalpy and entropy to predict the outcome. (Guide: “When enthalpy and entropy pull in opposite directions”; Practice Q4)
- I can evaluate a claim such as “exothermic means favoured” with a calculation and a reason. (Practice Q7(c))
- I can decide whether enthalpy or entropy drives a favoured process. (Practice Q6(d))
All ticked? Move on to Topic 9.4, Thermodynamic and Kinetic Control, or return to the course roadmap.