[Chemithon] Catalysis - The Engine of Chemistry
Last revised 7/27/2026

[Chemithon] Catalysis - The Engine of Chemistry

Secondary

From energy barriers and everyday examples to Gibbs free energy, Arrhenius kinetics, and enzyme mechanisms

Catalysis is not an obscure laboratory technique — it is the mechanism by which your digestive enzymes work, your car's exhaust is cleaned, bread rises, and roughly half of humanity's food supply is made possible. This two-part collection builds from atoms and energy barriers all the way to enzyme kinetics, transition-state theory, TON/TOF performance metrics, and the design principles of modern catalysts. The first part develops intuition: why reactions have energy barriers, what catalysts actually do, and where catalysis appears in everyday life. The second part develops rigour: Gibbs free energy, the Arrhenius equation, reaction coordinate diagrams, homogeneous vs. heterogeneous catalysis, autocatalysis, inhibition, and the molecular machinery of enzymes.

ChemistryBiochemistryPhysical ChemistryCompetition PrepChemithon
2Modules18Sessions173Cards51Quizzes

Modules in this Collection’s System

Hover a module to read it directly

Atoms, Bonds, and Why Reactions Happen

6Sessions

Why Reactions Need Help

12Sessions

What You'll Walk Away With

  • A labelled reaction coordinate diagram showing Eₐ (uncatalysed), Eₐ (catalysed), and ΔG
  • The Arrhenius equation written out with every symbol defined and a worked example of Eₐ reduction
  • A comparison table: homogeneous vs. heterogeneous catalysis (phase, selectivity, separation, examples)
  • A summary of Michaelis–Menten kinetics: Km, Vmax, rate law, and what saturation means physically
  • A list of four everyday catalysis examples with the catalyst and its role identified in each

You'll Have Answers To

  • ?What is the difference between thermodynamics and kinetics, and why does this distinction matter for catalysis?
  • ?How does the Arrhenius equation quantify the relationship between activation energy, temperature, and reaction rate?
  • ?What does a catalyst actually do at the molecular level — and equally important, what can it never do?
  • ?Why does a catalyst increase both the forward and reverse reaction rates by the same factor?
  • ?How do homogeneous and heterogeneous catalysts differ in mechanism, selectivity, and practical use?
  • ?What is a transition state, and how does a catalyst stabilise it to lower the activation barrier?
  • ?How do enzyme active sites achieve extraordinary reaction rates and near-perfect selectivity?
  • ?What are TON and TOF, and what do they reveal about the efficiency of a catalyst?
  • ?How does autocatalysis differ from conventional catalysis, and why can it produce sigmoidal kinetics?
  • ?Why do inhibitors not simply reverse catalysis, and how do competitive and non-competitive inhibitors differ?

Critical Concepts Explored

Activation energy (Eₐ) — the energy barrier molecules must overcome for a reaction to proceedGibbs free energy (ΔG = ΔH − TΔS) — the thermodynamic master variable that determines spontaneityArrhenius equation (k = Ae^{−Eₐ/RT}) — quantifies how rate constant depends on temperature and activation energyTransition state — the fleeting, highest-energy arrangement of atoms during a reaction; what catalysts stabiliseReaction coordinate diagram — plots potential energy vs. reaction progress, showing Eₐ and ΔGHomogeneous catalysis — catalyst and reactants in the same phase; high selectivity, harder to separateHeterogeneous catalysis — solid catalyst with fluid-phase reactants; industrially dominant, easy separationEnzyme kinetics — Michaelis–Menten model, Km, Vmax, and the biological origins of catalytic specificityTurnover number (TON) and turnover frequency (TOF) — metrics for catalytic productivity and efficiencyAutocatalysis — a reaction whose product is itself a catalyst, generating positive feedback and sigmoidal kineticsCompetitive vs. non-competitive inhibition — mechanisms by which molecules suppress catalytic activityMaxwell–Boltzmann distribution — the energy spread among molecules that determines what fraction can cross EₐHeterogeneous surface catalysis steps: adsorption → surface reaction → desorptionChiral/asymmetric catalysis — producing only one enantiomer through selective transition-state stabilisationPhotocatalysis — using light energy to drive reactions beyond what thermal catalysts can achieve
Gold Quotes