Chemical Kinetics

Thermodynamics tells us whether a reaction can happen; chemical kinetics tells us how fast it actually does. This chapter — worth a steady 5-7 Board marks and 2-3 JEE/NEET questions every year — builds the science of reaction rates from scratch. We define average and instantaneous rate, write the rate law $\text{Rate} = k[A]^x[B]^y$ and learn what the rate constant $k$, the order, and the molecularity each mean. We then derive and apply the integrated rate equations for zero-order ($[R] = [R]_0 - kt$) and first-order ($k = \frac{2.303}{t}\log\frac{[R]_0}{[R]}$) reactions, work out half-lives ($t_{1/2} = \frac{0.693}{k}$ for first order), and handle pseudo-first-order reactions. Finally we explain why rate rises with temperature using the Arrhenius equation $k = A e^{-E_a/RT}$, interpret activation energy and the Maxwell-Boltzmann distribution, describe how collision theory and proper molecular orientation control reaction, and see how a catalyst speeds a reaction by lowering the activation energy. Every formula, graph and numerical technique an exam can ask is covered.