In order to calculate ΔH° for a reaction which of the following sets represents numerical values that would be required?

• A. ΔG°, ΔS°, K
• B. ΔG°, ΔS°
• C. ΔG°, ΔS°, T
• D. None of these sets is sufficient, the standard enthalpies of formation are needed.

Answer: (C)

Verified step by step guidance

1. Understand that ΔH° represents the standard enthalpy change of a reaction, which is a measure of the heat absorbed or released during a chemical reaction under standard conditions.
2. Recall the relationship between ΔG° (standard Gibbs free energy change), ΔS° (standard entropy change), and ΔH° using the Gibbs free energy equation: ΔG° = ΔH° - TΔS°. This equation shows how these thermodynamic quantities are interrelated.
3. Identify that to solve for ΔH°, you need the values of ΔG°, ΔS°, and the temperature (T) at which the reaction occurs. This is because the equation can be rearranged to solve for ΔH°: ΔH° = ΔG° + TΔS°.
4. Recognize that the sets provided in the problem do not include temperature (T), which is essential for calculating ΔH° using the Gibbs free energy equation. Therefore, none of the sets are sufficient without the temperature.
5. Conclude that the correct approach to calculate ΔH° for a reaction is to use the standard enthalpies of formation of the reactants and products, if available, or to use the equation ΔH° = ΔG° + TΔS° with the necessary values including temperature.