The phrase “decrease in entropy” means that a system has become more organized and predictable.
This can happen with many types of reactions, including chemical reactions or changes to the environment.
For instance, when you mix two solutions together they will usually decrease in entropy.
Because their molecules are dissolving into one another.
When water freezes it decreases in entropy. When water evaporates, it also decreases in entropy.
A decrease in entropy is associated with which type of reaction?
A chemical reaction or changes to the environment would typically result in a decrease in entropy because they become more organized and predictable.
For instance, when you mix two solutions together their molecules dissolve into one another and the temperature usually drops.
When ice melts, its molecules are more disorganized than when they were solid.
The same concept applies for evaporation:
Liquids only have enough energy to escape from solids if all of the liquid has reached a vapor state.
At that point it can’t get any more chaotic!