Spontaneous reactions ________.
always release free energy***
always result in increase disorder of the system
always take place at a rapid rate
are always exothermic
Spontaneous reactions always release free energy. Free energy is the energy available to do work, and in spontaneous reactions, it is released. To understand how to determine if a reaction is spontaneous, you can use the concept of Gibbs free energy (ΔG). The equation for Gibbs free energy change (ΔG) is:
ΔG = ΔH - TΔS,
where ΔH is the change in enthalpy (heat) of the system, ΔS is the change in entropy (disorder) of the system, and T is the temperature in Kelvin.
If ΔG is negative (ΔG < 0), the reaction is spontaneous and releases free energy. This means that the products of the reaction have lower energy than the reactants, and the reaction will proceed towards the products. On the other hand, if ΔG is positive (ΔG > 0), the reaction is non-spontaneous and requires an input of energy to proceed.
Therefore, spontaneous reactions always release free energy, while non-spontaneous reactions require an input of energy. Keep in mind that the spontaneity of a reaction is not related to the rate of the reaction or whether it is exothermic or endothermic.