# How is entropy related to the spontaneity of a reaction?

##### 1 Answer

Generally a reaction will occur spontaneously if the entropy increases, but the enthalpy is also negative, or small and positive, according to Gibbs free energy equation.

#### Explanation:

Entropy (

In a closed system, entropy always increases over time. In an open system, energy can be added to a system to cause a decrease in entropy, but this is not necessarily a spontaneous reaction.

If entropy (disorder) increases, and the reaction enthalpy is exothermic (

The Gibbs free energy equation is:

#DeltaG = DeltaH - TDeltaS#

A reaction will be spontaneous if the change in

For the product of temperature times

Since the cosmos (observable universe) is essentially a closed system, entropy will continue to increase until the universe essentially ceases to exist.