Chapter 16

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  1. general formula for units of k (rate constant)
    units = (L/mol)order - 1 /unit of time
  2. rate expression
    • -1/a x Δ[A]/Δtime = same for b but for c/d
    • 1/c x Δ[C]/Δtime (no negative sign
  3. rate law
    rate = k[A]x[B]y (the reactants); the exponents x & y are orders
  4. you need to average the values of k to get
    full credit
  5. integrated rate law for 1st order rxns
    • - kt = ln[A]t - ln[A]
    • (rate constant)(time point)=ln[concentration of A at time point] - ln[intitial concentration of A] OR...
    • - kt = ln ([A]t / [A])
    • ororororororoororor
    • [At] = [A]e-kt
  6. second order reaction half life
    • DOES depend on initial concentration:
    • t1/2 = 1/k[A] initial
  7. first order reaction half life
    k = ln(2)/t1/2
  8. second order reaction (used to find concentration)
    • follows slope of a straight line (y = mx + b)
    • 1/[At] = kt + 1/[A]
  9. it takes longer for HALF of the _______ concentration to be consumed
    smaller concentration; because a smaller concentrsation means there is a smaller quantity of solute meaning it took longer to be consumed because the reaction ran more slowly
  10. return to make a flashcard of page 41 in the notes
  11. collision theory
    matter is composed of microscopic particles (molecules/atoms/ions) that are constantly moving and sometimes collide and react
  12. activation energy
    the minimum amount of energy that the reactants must have (before collsions) in order for the reaction to take place; for the reaction to take place the two molecules also must be positioned correctly
  13. transition state
    that state at which there is an intermediate structure which is composed of the reactants combined but not yet separated; represented by the peak on a potential energy profile; the activated complex is present here
  14. activated complex
    the species that exists when reactants are combined but not yet separated; can be found at the peak on a potential energy profile
  15. arrhenius equation
    k = Ae-Ea/RT
  16. molecularity
    • the number of reactant molecules shown in each elementary equation; ex:
    • A --> products = unimolecular
    • A + B --> products = bimolecular
    • A + C + D --> products = termolecular
  17. catalyst
    a substance that increases the rate of a chemical reaction without itself undergoing a permanent chemical change in the process; can be identified by observing that whatever about is added or consumed at the beginning of a reaction, the same amount will be produced or remain at the end
Card Set
Chapter 16
Gen Chem II
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