AP Chemistry Unit 9

2. A real process that results in net change and increased entropy in the universe.
4. An idealized process that can be reversed without net change to the system or surroundings.
5. The heat content of a system at constant pressure; positive for endothermic and negative for exothermic reactions.
9. A thermodynamic quantity that indicates the spontaneity of a process; calculated as ΔG = ΔH – TΔS.
11. The part of the universe being studied, typically the chemical reaction or physical change.
13. A reaction with a positive ΔG; absorbs free energy and is nonspontaneous.
16. The enthalpy change measured under standard conditions.
19. A physical change (e.g., melting, boiling) that involves changes in entropy and enthalpy.
21. A reaction with a negative ΔG; releases free energy and is spontaneous.
23. Different ways particles can be arranged; more microstates mean higher entropy.
24. The measurement of heat flow in a chemical or physical process.
25. Reactions that are linked such that the energy released by one drives the other.
26. A process that occurs naturally under certain conditions without external energy input.
27. The effect of temperature on ΔG, depending on the signs of ΔH and ΔS.

1. The entropy value of a substance at standard conditions.
3. The change in free energy when 1 mole of a compound forms from its elements in their standard states.
6. States that the entropy of a perfect crystal at absolute zero is zero.
7. Everything outside the system that can exchange energy with it.
8. The total enthalpy change for a reaction is the same, no matter how many steps the reaction is carried out in.
10. A process that requires continuous energy input to occur.
11. The change in entropy measured under standard conditions.
12. A value used to determine the direction of shift to reach equilibrium, used in the Gibbs free energy equation ΔG = ΔG° + RTlnQ.
14. The sum of entropy changes in the system and surroundings; used to determine spontaneity.
15. The change in free energy under standard conditions (1 atm, 298 K, 1 M concentrations).
17. The study of energy changes, particularly heat and work, in chemical processes.
18. States that the total entropy of the universe always increases for a spontaneous process.
20. A measure of disorder or randomness in a system; increases when systems become more disordered.
22. A value that expresses the ratio of products to reactants at equilibrium; related to ΔG° by ΔG° = –RTlnK.