What is Gibbs free energy and why is it significant in chemical reactions?

What are standard conditions in the context of Gibbs free energy calculations?

Given ΔG° = -40 kJ/mol and R = 8.314 J/mol·K, calculate the equilibrium constant K at 298 K.

For a reaction at 350 K with ΔH = 150 kJ/mol and ΔS = 400 J/mol·K, calculate the Gibbs free energy change.

If Q < K for a given reaction, what is the most likely direction of the reaction?