Question

1. Consider the reaction: 2 NO (g) + 2 H2 (g) → N2 (g) + 2 H2O (g). If the rate of change in NO is -0.68 M s^-1 then write the rate of change for the other reactants and products. What is the rate of the reaction?

2. Consider the reaction: CH3COOC2H5 (aq) + OH- (aq) → CH3CO2- (aq) + CH3CH2OH (aq)
The reaction is known to be first order in CH3COOC2H5 and first order in OH-. The second- order rate constant for the overall reaction is 0.11 dm^3 mol^-1 s^-1. If the initial concentration of [OH-] is 1.0 x 10^-2 mol dm^-3 and the initial concentration of CH3COOC2H5 is 1.8 x 10^-4 mol dm^-3 then what is the concentration of OH- and CH3COOC2H5 after 225 s?

HINT: There are two ways to go about this problem – on involves an approximation that the concentration of one reactant does not change and the other uses an exact but less familiar expression from your text. You may use either.

3. Integrated Rate Laws
A) In the content scaffold and in the text we found the second order integrated rate law for the reaction A → Products by setting the following to expressions for rate equal and integrating: ???? = -d[A]/dt and ???? = ?r [?]^-2

How would these expressions change if the reaction was 2 A → Products?
What is the integrated rate law for the reaction 2 A → Products?
HINT: You should get a very similar (but not identical) answer as for the reaction A → Products?

B) If a reaction A → Products has the rate law ???? = ?r [?]^0.5, then what is the integrated rate law for this reaction?

4. Consider the simple reversible gas phase reaction M + N ⇌ P + U at equilibrium.

a) Write the equilibrium constant for this reaction in terms of the forward rate constant, k1 and the reverse rate constant, ?'1

b) As the temperature of this reaction increases, the reaction favors products. Does the forward or reverse reaction have the larger activation energy? Briefly explain your answer in terms of the relative temperature dependence of k1 and?'1.

c) What is the activation energy for the forward reaction if the rate constant triples when the temperature is raised from 25.0°C to 55.0°C?

5. Consider the following nucleophilic substitution reaction:

Ni(CO)4 + PPh3 → Ni(CO)3PPh3 + CO

In 1968, Day and coworkers proposed the following mechanism.

Ni(CO) ⇌ Ni(CO) + CO (forward reaction ?1 and reverse reaction ?'1 )

Ni(CO) + PPh →(k2) Ni(CO)3 PPh3

Experiments show that the overall reaction is (1) first order in Ni(CO)4 and (2) shows a more complex dependence on the concentration of PPh3 and CO. At high PPh3 concentrations, the reaction appears to be (3) solely first order in Ni(CO)4.

Use the mechanism above to derive a rate law that is consistent with the experimental observations given. Clearly explain in multiple sentences how your proposed rate law is consistent with each of the three experimental observations.

Answer 1