Tutorial -CHE 206 1.0 Chemical Kinetics
1. The effective rate constant for a gaseous reaction which has a Lindemann–
Hinshelwood mechanism is 1.7×10-3 s-1 at 1.09 kPa and 2.2×10-4 s-1 at 25 Pa.
Calculate the rate constant for the activation step in the mechanism.
2. A rate constant is found to fit the expression kr = (4.98 × 1013)e-(4972 K)/T dm3 mol-1
s-1 near 25 °C. Calculate Δ‡G for the reaction at 25 °C.
3. The mechanism of a composite reaction consists of a fast preequilibrium step
with forward and reverse activation energies of 27 kJ mol-1 and 35 kJ mol-1,
respectively, followed by an elementary step of activation energy 15 kJ mol-1.
What is the activation energy of the composite reaction?
4. The rate constant for the decomposition of a certain substance is 2.25×10-2 dm3
mol-1 s-1 at 29 °C and 4.01×10-2 dm3 mol-1 s-1 at 37 °C. Evaluate the Arrhenius
parameters of the reaction.
5. The rate law for the reaction was reported as d[C]/dt=kr[A][B][C]-1. Express the
rate law in terms of the reaction rate v; what are the units for kr in each case
when the concentrations are in moles per cubic decimetre?
6. The second-order rate constant for the reaction A +2 B→C+D is 0.34 dm3 mol-1
s-1. What is the concentration of C after (i) 20 s, (ii) 15 min when the reactants
are mixed with initial concentrations of [A]=0.027 mol dm-1 and [B]=0.130 mol dm3?
7. The equilibrium A⇌B+C at 25 °C is subjected to a temperature jump which
slightly increases the concentrations of B and C. The measured relaxation time is
3.0µs. The equilibrium constant for the system is 2.0×10-16 at 25 °C, and the
equilibrium concentrations of B and C at 25 °C are both 0.20 mmol dm-3.
Calculate the rate constants for the forward and reverse steps.