Orgo Ch 4.9-4.11

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Orgo Ch 4.9-4.11
2013-09-30 23:16:05
CHM 201

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  1. Each reaction has its own characteristic __. Its value depends o the __, especially the __. This __ dependence is expressed by the __.
    • rate constant, kr
    • conditions of the reaction
    • temp
    • temp dependence
    • Arrhenius equation
    • kr=Ae-Ea/RT
  2. Explain the components of the Arrhenius equation?
    • A= a constant (the "frequency factor")
    • Ea= activation energy
    • R= the gas constant (8.314 J/ Kelvin-mole)
    • T= the absolute temp
  3. The __ is the minimum kinetic energy the molecules must have to overcome the repulsions between their electron clouds when they collide. The exponential term e^(-Ea/RT) corresponds to the __ in which the particles have the __ needed to react.
    • activation energy, Ea
    • fraction of collisions
    • minimum energy, Ea
  4. The __ accounts for the frequency of collisions and the fraction of collisions with the proper orientation for the reaction to occur. In most cases, only a small fraction of collisions occur between molecuels with enough ___ and with just the __ for reactions to occur. Far more collisions occur without enough __ or without the __, adn the molecules simply bounce off each other.
    • frequency factor A
    • speed
    • right orientation
    • kinetic energy
    • proper orientation
  5. The __ implies that the rate of the reaction depends on the __ with kintetic energy of at least Ea.
    • Arrhenius equation
    • fraction of collisiosn
  6. Because the __ increases quickly when the temp is raised, it might seem that raising the temp would be a good way to save time by making reactions go faster. What is the problem, however?
    • relative rate constant (krel)
    • allĀ reactions are accelerated, including all the unwanted side reactions (don't want that)
  7. The __ represents the energy differences between the __ and the __, the highest energy state in a molecular collision that leads to reaction.
    • activation energy Ea
    • reactants
    • transition state
  8. In effect, __ is the barrier that must be overcome for the reaction to take place. The value of Ea is always __ and its magnitude depndds on the __ of the __.
    • activation energy
    • positive
    • relative energy
    • transition state
  9. The term __ implies that this configuration is the __ between the reactants and the products, and the molecules can either go on to products or return to reactants.
    • transition state
    • transition
  10. Unlike the reactants or products, a transition state is __ and cannot be __. It is not an __ because an __ is a species taht exists for some finite length of time, even if it very short.
    • unstable
    • cannot be isolated
    • intermediate x2
  11. An __ has at least some stability, but the __ is a transient on the path from one __ to another.
    • intermediate
    • transition state
    • intermediate
  12. Transition states have __ because bonds must begin to __ before other bonds can __.
    • higher energies
    • break
    • form
  13. vertical axis of a reaction energy diagram is __.
    horizontal axis?
    • the total potential energy of all the species involved in the reaction
    • reaction coordiate, which symbolizes the progress of the reaction, going from the reactants on the left to the products on the right
  14. highest point on the graph
    what is activation energy on the graph?
    • transition state
    • energy difference between reactants and the transition state
  15. If a __ were added to the reaction, it would create a __ of lower energy, thereby lowering the __ and increasing the __. Addition of a __ would not change the enthalpies of the reactants and products, however, so the heat o reaction adn the equilibrium constant would be unaffected.
    • catalyst
    • transition state
    • activation energy
    • reaction rate
    • catalyst
  16. Explain reactive intermediates?
    stable as long as they don't collide with other atoms or molecuels
  17. energy maxima and energy minima
    • e max: high points; unstable transition states
    • e min: low points; intermediates
  18. In a multistep reaction, each step has its own characteristic rate. There can only be one overall reaction rate, however, and it is controlled by the __.
    rate limiting (or rate determining) step
  19. In general, the __ of a multistep reaction is the __ adn it determines the overall rate.
    • highest-energy step
    • bottleneck

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