# Entropy change in chemical reactions

Entropy change in chemical reactions
• The entropy change for a chemical reaction among pure, crystalline substances is zero at the absolute zero K by the Third law of thermodynamics.
• Therefore, the entropy change of a chemical reaction at 298 K is simply the difference between the sum of the standard entropies of the products and the sum of the standard entropies of the reactants.

• The entropy changes at other temperatures