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Entropy, Enthalpy, and Free Energy - Coggle Diagram

- - - - Entropy of the products differs from the entropy of the reactants
      - The difference is the entropy change of the reaction (ΔS)
      - Given by the equation: ΔS = ΣS°(products) - ΣS°(reactants)
      - Units: J/K mol
  - - - Calculate the entropy change during the reaction:
      - CaCO3(s) -> CaO(s) + CO2(g)
      - ΔS°(CaO(s)) = 92.9 J/K mol
      - ΔS°(CO2(g)) = 213.6 J/K mol
      - ΔS°(CaCO3(s)) = 39.75 J/K mol
    - - ΔS = ΣS°(products) - ΣS°(reactants)
      - ΔS = [ΔS°(CaO) + ΔS°(CO2)] - ΔS°(CaCO3)
      - ΔS = (92.9 + 213.6) - 39.75
      - ΔS = 160.4 J/K mol
  - - - Entropy of gases is higher than that of solids or liquids
      - Gases are highly disordered and have much higher entropy values
      - Any reaction with an increase in the number of gas molecules leads to an increase in entropy
- - - - Enthalpy changes explain why exothermic reactions occur
      - Enthalpy changes cannot explain why endothermic reactions occur
      - Feasible reactions become spontaneous when ΔG < 0
      - ΔS (change in entropy) must also be considered when determining feasibility
  - - - When heat energy flows into a reaction, it increases the entropy of the particles
      - ΔH° (change in enthalpy) must be calculated
      - If the ΔH° of the reactants and products are given, the overall enthalpy change (ΔH) can be calculated using the equation: ΔH = ΣΔH°(products) - ΣΔH°(reactants)
      - Elements always have a ΔH° = 0
  - - - Data for the reduction of Fe2O3 by C are shown below:
      - 2Fe2O3(s) + 3C(s) -> 4Fe(s) + 3CO2(g)
      - ΔH°(Fe2O3) = -824.2 kJ/mol
      - ΔH°(Fe) = 0.0 kJ/mol
      - ΔH°(CO2) = -393.4 kJ/mol
      - Calculate the value of ΔH° for the reaction at 298 K
    - - ΔH = ΣΔH°(products) - ΣΔH°(reactants)
      - ΔH = 4(0.0) + 3(-393.4) - 2(-824.2)
      - ΔH = +467.9 kJ/mol
- - - - AG takes into account both the entropy changes and the enthalpy change at a particular temperature
      - AG = ΔH - TΔS°
      - AG is negative for spontaneous reactions
  - - - When a change of state occurs, ΔG° = 0
      - By using ΔG = ΔH - TΔS°, it can be derived that ΔS° = ΔH/T or ΔH = TΔS
      - This can be used to calculate the entropy change for a change of state