In chemical kinetics, the half-life (t½) is the time it takes for half of the reactant to be used up in a reaction.
- For example, if you start with 100 molecules, after one half-life only 50 remain.
- After another half-life, 25 remain, and so on.
🔹 Key points:
- First-order reactions: The half-life is constant and does not depend on the starting concentration.
- Second-order (and higher) reactions: The half-life depends on the initial concentration (it changes as the reaction goes on).
In short: Half-life tells us how quickly a reaction proceeds and is very useful in studying reaction rates (like radioactive decay or drug breakdown in the body).