Problem: The reaction described by H2(g) + I2(g)  yields 2HI(g) has an experimentally determined rate law of rate of reaction= k [H2] [I2] some proposed mechanisms for this reaction are:Mechanism a.1. H2(g) + I2(g)  yields (k1 on top of the arrow) 2HI (g)   (one step reaction)Mechanism b.(1) I2(g) equilibrium arrow (k1 on top of the arrow, and k-1 on the bottom of the arrow ) 2I (g)   (fast equilibrium )(2) H2(g) + 2I(g)  yields (k2 on top of the arrow)  2HI(g)  (slow)Mechanism c.(1) I2(g) equilibrium arrow   (k1 on top of the arrow, k-1 on the bottom of the arrow) 2I(g)(2) I(g) +H2(g)  equilibrium arrow (k2 on the top and k-2 on the bottom of the equilibrium arrow)  yields H2I(g) (Fast equilibrium)(3) H2I(g)  yields ( k3 on top of the arrow)   HI(g) + I(g)  (slow)A) which of these mechanisms are consistent with the observed rate law?a. mechanism ab. mechanism bc. mechanism cB) in 1967 J.H Sullivan showed that this reaction was dramatically catalyzed by light when the energy of the light was sufficient to break the I-I bond in an I2 molecule. Which mechanism(s) are consistent with both the rate law and this additional observation?a. Mechanism ab. Mechanism bc. mechanism c

FREE Expert Solution

We are asked to determine which of the given mechanisms are consistent with the observed rate law:

Rate=[H2][I2]

A. The reaction mechanism that is consistent with the given rate law expression.

When a rate law is given, the reaction mechanism consistent with the rate law is the slow step in the reaction mechanism.

 rate law only involves the reactants
▪ the coefficients of the reactants in the slow step are the order of the reaction with respect to that reactant
▪ Rate Law has a general form of:

Rate Law = kXaYb

k = rate constant
X & Y = reactants
a & b = reactant orders

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Problem Details

The reaction described by H2(g) + I2(g)  yields 2HI(g) has an experimentally determined rate law of rate of reaction= k [H2] [I2] some proposed mechanisms for this reaction are:

Mechanism a.

1. H2(g) + I2(g)  yields (k1 on top of the arrow) 2HI (g)   (one step reaction)


Mechanism b.

(1) I2(g) equilibrium arrow (k1 on top of the arrow, and k-1 on the bottom of the arrow ) 2I (g)   (fast equilibrium )

(2) H2(g) + 2I(g)  yields (k2 on top of the arrow)  2HI(g)  (slow)


Mechanism c.

(1) I2(g) equilibrium arrow   (k1 on top of the arrow, k-1 on the bottom of the arrow) 2I(g)

(2) I(g) +H2(g)  equilibrium arrow (k2 on the top and k-2 on the bottom of the equilibrium arrow)  yields H2I(g) (Fast equilibrium)

(3) H2I(g)  yields ( k3 on top of the arrow)   HI(g) + I(g)  (slow)


A) which of these mechanisms are consistent with the observed rate law?

a. mechanism a

b. mechanism b

c. mechanism c


B) in 1967 J.H Sullivan showed that this reaction was dramatically catalyzed by light when the energy of the light was sufficient to break the I-I bond in an I2 molecule. Which mechanism(s) are consistent with both the rate law and this additional observation?

a. Mechanism a

b. Mechanism b

c. mechanism c

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