Here’s a explanation without any equations:
The standard entropy change of a reaction tells us how the disorder of a system changes when a reaction happens under normal conditions (like room temperature and pressure).
- If the products are more disordered than the reactants, the entropy change is positive.
- If the products are more ordered than the reactants, the entropy change is negative.
Examples:
- Melting ice: Solid ice is ordered, liquid water is more random → entropy increases.
- Condensing steam: Gas is very random, liquid is more ordered → entropy decreases.
In short: It tells us whether a reaction makes the system more disordered or more ordered under standard conditions.