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    Reaction Mechanisms

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    The reaction of a hyrogrn halide A with an olefin B to give product P according to the stoichiometric relationship:

    A + B -> P

    is proposed to occur by the following mechanism:

    2A <-> A2 (fast to equilibrium)

    A + B <-> C (fast to equilibrium)

    A2 + C -> P + 2A (slow)

    (a) Based on this mechanism, derive an expression for the velocity (rate) of the reaction of the concentration of only reactants and stable product.

    (b) In a particular ecperiment, equal concentrations of A and B are mixed together, and both the inital rate vo and the half-life t 1/2 are determined. Based on your answer to part (a), predict for a subsequent experiment:

    (i) The effect on vo if the initial concentrations of both A and B are doubled.

    (ii) The effect on t 1/2 if the initial concentrations of both A and B are doubled.

    (iii) The effect on vo if the initial concentration of A id unchanged and the initial concentration of B is increased tenfold.

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    https://brainmass.com/chemistry/energetics-and-thermodynamics/reaction-mechanisms-8602

    Solution Preview

    The whole reaction can be written as:
    2A + A + B <-> A2 + C -> P + 2A
    or, 3A + B <-> (A2C) -> P + 2A

    Therefore,
    d[P]/dt = k2*[(A2C)]

    For steady state:
    d[A2C]/dt = k1*[A]^3*[B] - k1'*[(A2C)] - k2*[(A2C)] = 0
    => [A2C] = k1*[A]^3*[B]/{k1'+k2}

    Therefore,
    d[P]/dt = k2*k1*[A]^3*[B]/k3 ...

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