4, How the equilibrium constant varies with the difference in energy between reactants and products

Q: What is the equilibrium constant KKK when the energies of reactants and products are the same?

A: When the energies are the same, K=1

Q: How does the equilibrium constant K change when one state has a higher energy than the other?

A: The equilibrium constant KKK becomes larger when the products are much more stable (lower in energy) than the reactants.

Q: What equation relates the equilibrium constant K to the energy difference between reactants and products?

A: The equation is:
ΔG=−RTln⁡K

Q: What does ΔG represent in the equation ΔG=−RTln⁡K?

A: ΔG is the free energy difference between the reactants and products, measured in kJ mol⁻¹.

Q: What are the components of the equation ΔG=−RTln⁡K?

• ΔG: Free energy change (kJ mol⁻¹)

• R: Gas constant (8.314 J K⁻¹ mol⁻¹)

• T: Temperature in kelvin (K)

• ln⁡K: Natural logarithm of the equilibrium constant

Q: How does the equation ΔG=−RTln⁡K help predict equilibrium composition?

A: It allows calculation of the amounts of reactants and products at equilibrium if the energy difference ΔG is known.

Q: Who derived the relationship between energy and the equilibrium constant?

A: The equation was derived by J. Willard Gibbs, an American physical chemist, in the 1870s.