Question

be sure to answer all parts. using data from the appendix, calculate δs o rxn and δssurr for each of the reactions and determine if each is spontaneous at 25°c. (a) 2 kclo4(s) → 2 kclo3(s) o2(g)

Answer 1

To determine the spontaneity of a reaction at 25°C, calculate the Gibbs free energy change (ΔG°) using the standard free energies of formation, enthalpies of formation, and standard entropies from Appendix G. A negative ΔG° indicates a spontaneous reaction, while a positive ΔG° indicates a nonspontaneous reaction.

Step-by-step explanation:

To determine if a reaction is spontaneous at 25°C, we need to calculate the change in Gibbs free energy (ΔG°). The Gibbs free energy can be obtained using the formula ΔG° = ΔH° - TΔS°, where ΔH° is the change in enthalpy, T is the temperature in Kelvin, and ΔS° is the change in entropy. The reaction would be considered spontaneous if ΔG° is negative, and nonspontaneous if ΔG° is positive.

For example, let's consider the reaction N₂H₄ (l) + O₂(g) → N₂(g) + 2 H₂O(l). Using standard free energies of formation, enthalpies of formation, and standard entropies from Appendix G, you perform the following steps:

1. Find the standard free energies of formation (ΔG°f), enthalpies of formation (ΔH°f), and standard entropies (S°) for all reactants and products.
2. Calculate ΔH° for the reaction using ΔH° = ΣΔH°f(products) - ΣΔH°f(reactants).
3. Calculate ΔS° for the reaction using ΔS° = ΣS°(products) - ΣS°(reactants).
4. Convert temperature from Celsius to Kelvin by adding 273.15 to the Celsius temperature.
5. Calculate ΔG° using the formula ΔG° = ΔH° - TΔS°.
6. Determine the sign of ΔG° to assess the spontaneity of the reaction at 25°C.

If ΔG° is negative, the reaction is spontaneous; if positive, it is nonspontaneous.