Final answer:
Determining whether entropy increases or decreases depends on the nature of the process, such as a gas condensing into a solid (entropy decreases) or a solid melting (entropy increases).
Step-by-step explanation:
To determine whether the entropy of a system is increasing or decreasing during a process, we must consider the nature of the process. Entropy, which is a measure of disorder in a system, tends to increase in spontaneous processes.
When a substance changes from a gas to a solid, like the condensing of iodine gas into a solid, the entropy decreases because the molecules in a solid are more ordered than in a gas. Conversely, when a solid melts into a liquid or a liquid vaporizes into a gas, entropy increases.
Regarding endergonic and exergonic reactions, an exergonic reaction releases energy and typically results in an increase in entropy. An endergonic reaction requires the input of energy and often leads to a decrease in entropy since the products are less disordered than the reactants.
When solving for changes in entropy, we use the appropriate thermodynamic equations. For reversible processes, the total entropy change of the universe should be constant, and for real, irreversible processes, the total entropy should increase.
Disordered states are more probable and communicate a greater entropy than ordered states. Calculating the increasing disorder of a system involves these principles, and the expected fate of the universe in entropic terms includes the presumption that the universe will continue to increase in entropy, leading to a state of maximum entropy, sometimes referred to as the 'heat death of the universe.'