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Cheat sheet · Class 12 · CBSE · Science Chemistry

Chemical Kinetics cheat sheet

The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.

CBSE Class 12 · Chemistry

Cheat sheet

Chapter 3Chemical Kinetics

First order half-life is constant: t½ = 0.693/k.

1. Rate

For aA→bBaA \to bB: rate =−1ad[A]dt=1bd[B]dt= -\dfrac1a\dfrac{d[A]}{dt} = \dfrac1b\dfrac{d[B]}{dt}.

  • Rate law: rate = k[A]^x[B]^y; order = x + y (found by experiment).
  • Molecularity: number of species in an elementary step (whole number).

2. Integrated Rate Laws

OrderEquationHalf-lifeUnit of k
Zero[A]=[A]0−kt[A] = [A]_0 - kt[A]02k\dfrac{[A]_0}{2k}mol L⁻¹ s⁻¹
Firstk=2.303tlog⁡[A]0[A]k = \dfrac{2.303}{t}\log\dfrac{[A]_0}{[A]}0.693k\dfrac{0.693}{k}s⁻¹

Pseudo-first-order: hydrolysis of ester in excess water.

3. Temperature

k=Ae−Ea/RTk = Ae^{-E_a/RT}
log⁡k2k1=Ea2.303R(T2−T1T1T2)\log\dfrac{k_2}{k_1} = \dfrac{E_a}{2.303R}\left(\dfrac{T_2 - T_1}{T_1T_2}\right)

Rate roughly doubles for a 10 K rise.

4. Key Points

  • Catalyst lowers Ea, doesn't change ΔG.
  • Collision theory: proper orientation + energy.
  • Radioactive decay is first order.
  • Order can be fractional or zero.

Remember: Rate law | zero & first order | Arrhenius

Chemical Kinetics: questions and notes

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