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Introduction to Rate Law

Rate laws describe how the rate of a chemical reaction depends on the concentration of reactants. They are essential for understanding reaction kinetics.

Key Concepts​

  • Rate of Reaction: Change in concentration of reactant or product per unit time
    • Rate = −Δ[Reactant]/Δt = Δ[Product]/Δt
  • Rate Law: Mathematical relationship between rate and reactant concentrations
    • General form: Rate = k[A]ᵐ[B]ⁿ
      • k = rate constant
      • m, n = reaction orders with respect to each reactant

Determining Rate Laws​

  1. Conduct experiments varying reactant concentrations
  2. Measure the reaction rate for each experiment
  3. Use ratios of rates to determine reaction order with respect to each reactant
  4. Combine results to form the overall rate law

Example​

For the reaction: A + B → Products

  • Experiments show doubling [A] doubles the rate → m = 1
  • Doubling [B] quadruples the rate → n = 2
  • Rate law: Rate = k[A]¹[B]²

Importance​

  • Predicts reaction behavior under different concentrations
  • Helps identify rate-determining steps and reaction mechanisms
  • Essential for industrial processes, laboratory experiments, and chemical design

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