Question

Calculate the change in Gibbs free energy for each of the following sets of ΔH∘rxn, ΔS∘rxn, and T. (Assume that all reactants and products are in their standard states.)

ΔH∘rxn=−84kJ, ΔS∘rxn=−157J/K, T=302K
Express your answer as an integer.

Answer 1

To find the change in Gibbs free energy, we use ΔG = ΔH° - TΔS°, converting units where necessary. Given ΔH° = −84 kJ, ΔS° = −157 J/K, and T = 302 K, ΔG is calculated to be −36.6 kJ.

Step-by-step explanation:

The student is asking how to calculate the change in Gibbs free energy (ΔG) given the standard enthalpy change of reaction (ΔH°rxn), the standard entropy change of reaction (ΔS°rxn), and the temperature (T). Using the provided values of ΔH°rxn = −84 kJ, ΔS°rxn = −157 J/K, and T = 302 K, we can calculate ΔG using the equation:

ΔG = ΔH° - TΔS°

First, make sure to convert all the units to be consistent, typically using kJ for energy. So we convert ΔS° from J/K to kJ/K by dividing by 1000:

ΔS° = −157 J/K × (1 kJ/1000 J) = −0.157 kJ/K

Now insert the values into the equation:

ΔG = (-84 kJ) - (302 K)×(-0.157 kJ/K) = −84 kJ + 47.414 kJ = −36.586 kJ

The change in Gibbs free energy for the reaction given is −36.6 kJ (when expressed as an integer).