Final answer:
Energetically-favourable reactions occur spontaneously while energetically-unfavourable reactions do not occur spontaneously. Spontaneity of a reaction depends on several factors, including the free energy change and the equilibrium constant.
Step-by-step explanation:
In chemistry, energetically-favourable reactions occur spontaneously while energetically-unfavourable reactions do not occur spontaneously.
Spontaneity of a reaction depends on several factors, including the free energy change (ΔG) and the equilibrium constant (K). If ΔG is negative and K is large, the reaction is considered energetically-favourable and will occur spontaneously.
On the other hand, if ΔG is positive and K is small, the reaction is considered energetically-unfavourable and will not occur spontaneously.