Provide an example of the entropy of different reactions and their spontaneity.

The entropy of a reaction can determine its spontaneity.

Entropy is a measure of the disorder or randomness of a system. In chemical reactions, the change in entropy (∆S) can be calculated by comparing the entropy of the products to the entropy of the reactants. If the products have a higher entropy than the reactants, then the reaction is said to have a positive ∆S value and is more likely to be spontaneous.

For example, the combustion of wood has a positive ∆S value because the reactants (wood and oxygen) have low entropy compared to the products (carbon dioxide, water vapour, and ash), which have high entropy. This means that the reaction is spontaneous and will occur without the need for external energy input.

On the other hand, the reaction between hydrochloric acid and sodium hydroxide has a negative ∆S value because the reactants have higher entropy than the products (salt and water). This means that the reaction is not spontaneous and requires external energy input to occur.

Overall, the entropy of a reaction can provide important information about its spontaneity and the energy required for it to occur.