Spontaneous Reactions vs. Nonspontaneous Reactions — What's the Difference?

Spontaneous Reactions and Nonspontaneous Reactions are terms used to categorize chemical reactions based on their natural tendency to occur. Spontaneous Reactions are those reactions that can occur without any external intervention. They tend to move towards a state of lower energy or increased disorder. This does not necessarily mean that Spontaneous Reactions are swift; some can be quite slow. However, the driving force for these reactions exists inherently due to the nature of the reactants and the conditions.

Nonspontaneous Reactions, in contrast, are those reactions that do not occur on their own under a set of conditions. They require an external source of energy to proceed. This energy can come in various forms, such as heat, light, or electricity. Nonspontaneous Reactions might be desired in various scenarios, but the push to make them occur must be externally provided.

The thermodynamic feasibility of Spontaneous Reactions and Nonspontaneous Reactions can often be determined by the Gibbs free energy change (∆G). If ∆G is negative, the reaction tends to be spontaneous, whereas if ∆G is positive, the reaction is typically nonspontaneous under standard conditions. However, it's crucial to note that even if a reaction is spontaneous thermodynamically, it might not be kinetically favorable, meaning it might need a catalyst or a particular condition to speed up the process.

Another noteworthy point is the reversibility of these reactions. While Spontaneous Reactions tend to move in a specific direction naturally, reversing them would typically result in Nonspontaneous Reactions. Conversely, making a Nonspontaneous Reaction proceed might be spontaneous in the reverse direction. These tendencies significantly impact various industrial and natural processes, as they determine the energy and resources needed for specific chemical transformations.