Provide an example of the Gibbs free energy of different reactions and their spontaneity.

The Gibbs free energy determines the spontaneity of a reaction. Negative ΔG values indicate spontaneous reactions.

The Gibbs free energy (ΔG) is a measure of the energy available to do work in a system. It is calculated using the equation ΔG = ΔH - TΔS, where ΔH is the change in enthalpy, T is the temperature in Kelvin, and ΔS is the change in entropy. A negative ΔG value indicates that the reaction is spontaneous, while a positive ΔG value indicates that the reaction is non-spontaneous.

For example, the hydrolysis of ATP to ADP and inorganic phosphate has a negative ΔG value of -7.3 kcal/mol. This indicates that the reaction is spontaneous and releases energy. Conversely, the synthesis of ATP from ADP and inorganic phosphate has a positive ΔG value of +7.3 kcal/mol, indicating that the reaction is non-spontaneous and requires energy input.

Another example is the combustion of glucose, which has a negative ΔG value of -686 kcal/mol. This reaction is highly spontaneous and releases a large amount of energy in the form of heat and light. In contrast, the reverse reaction, the synthesis of glucose from carbon dioxide and water, has a positive ΔG value of +686 kcal/mol and is non-spontaneous under normal conditions.

Overall, the Gibbs free energy is a useful tool for predicting the spontaneity of reactions and understanding the energy changes that occur during chemical reactions.