Predicting Entropy Changes from Reactions

[Mariyam Oladele 1E]

In a couple of textbook questions such as 4H.7 we are asked to predict whether there is an increase or decrease in the entropy of the system. How are we able to do their by just looking at the chemical reaction?

[ruby_sievers_3H]

If you look at the physical states of the products/reactants in the chemical reaction you will be able to determine if there is an increase or decrease in entropy. Gas has the most entropy, then liquid, then solid. For example, If the reaction contains a solid reactant that forms a gas product, entropy increases

[Evonne Xu 3I]

Entropy relates to the disorder of the system, which is related to the states that the reaction includes. If you go from solid to liquid, or liquid to gas, entropy will increase as you are increasing disorder. If in the reaction you go from liquid to solid or gas to liquid, then entropy will decrease as it is becoming more ordered.