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 entropy as a measure of how dispersed the matter and the energy of a system are. (Guide: “Entropy as dispersal”)
- I can explain why some endothermic processes still happen, using the idea that energy is not the only factor. (Guide: “Why energy alone is not enough”)
- I can explain, using particle pictures, why entropy increases from solid to liquid to gas. (Guide: Figure 1; Practice Q1)
- I can explain why vaporisation gives a much larger entropy increase than melting. (Guide: “Matter dispersal in phase changes”; Practice Q2)
- I can use the kinetic-energy distribution to explain why the entropy of a substance increases with temperature. (Guide: Figure 2; Practice Q3)
Skills
- I can predict the sign of ΔS for any phase change and its reverse. (Practice Q1, Q7(a))
- I can predict the sign of ΔS when a gas expands or is compressed at constant temperature. (Guide: Worked example 2; Practice Q5(a))
- I can predict the sign of ΔS for a reaction by counting moles of gas only, ignoring solids and liquids. (Guide: Worked example 1; Practice Q2, Q6(a))
- I can rank entropy changes for several processes by size, using phase and the change in moles of gas. (Guide: Worked example 1; Practice Q2)
- I can explain how changing a product’s state, such as H₂O(l) to H₂O(g), changes ΔS for a reaction. (Practice Q6(b))
Reasoning
- I can recognise when equal moles of gas mean the sign of ΔS cannot be predicted by counting, and say so. (Guide: Worked example 1; Practice Q4)
- I can say when two effects cannot be ranked without data. (Practice Q5(c))
- I can reject the claim that the sign of ΔH fixes the sign of ΔS, with a reason. (Practice Q6(c))
- I can support an entropy claim with particle-level evidence, naming whether matter or energy becomes more dispersed. (Practice Q5, Q7)
All ticked? Move on to Topic 9.2, Absolute Entropy and Entropy Change, or return to the course roadmap.