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Chapter 14

Chapter 14: Chemical Kinetics

Rates of reaction and the particulate nature of matter

  • Kinetics:
    • Rates of reaction (speed)
    • The sequential steps of a reaction
  • Affect the rates?
    • Concentration of the reactants
      • The more stuff that is present, the more collisions will occur and the rate of reaction will increase
    • Temperature of reaction
      • As the temperature increases, the rates also increase
    • Structure and orientation of particles
      • B-A + C → A-C + B
      • A-B + C -/->

Rates in a chemical reaction

  • Rate = $\frac{\text{Concentration Change}}{\text{Time Change}}$
  • 2 N2O5 → 4NO2 + O2
  • Rate of formation for NO2: $\frac{\Delta [NO_2]}{\Delta t} = 3.7\times 10^{-5} M s^{-1}$
  • Rate for formation for O2: $9.00\times 10 ^{-6} M s^{-1}$
  • Rates must be positive
  • General rate of reaction
    • Not formation or decomposition, but the rate of the entire reaction
    • Use stoichiometry to make sure that everything is equal to each other
    • Get one rate of reaction
      • Take each of the terms and divide it by the stoichiometry

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  • Instantaneous rate: rate of reaction at a single point in time
    • It is the slope tangent to the curve

The Rate Law

  • How the reaction proceeds over the entirety of the reaction
  • aA + bB → products
    • Rate Law: $\text{Rate} = k[A]^m[B]^n$
      • These exponents tell us how sensitive the reaction is to changes in concentration 
      • These exponents must be experimentally determined
        • This is because there are sequential steps for the reaction
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