5/12/2008
Ex 22.1a
HW 5 solutions
5/12/2008
HW5 solutions
• The rate of the reaction A + 2 B ‐> 3 C + D was reported as 1.0 mol dm‐3 s‐1. State the rates of formation and consumption of the participants.
1
5/12/2008
22.3a
• The rate law for the reaction in Exercise 22.1a was found to be v
= k[A][B]. What are the units of k? Express the rate law in terms of the rates of formation and consumption of (a) A, (b) C.
HW5 solutions
3
At 518°C, the rate of decomposition of a sample of gaseous acetaldehyde, initially at a pressure of 363 Torr, was 1.07 Torr s‐1 when 5.0 per cent had reacted and 0.76 Torr s‐1 when 20.0 per cent had reacted. Determine the order of the reaction.
5/12/2008
22.7a
HW5 solutions
4
22.12a
• Show that t1/2 ~ 1/[A]n – 1 for a reaction that is nth‐order in A.
• The rate constant for the first‐order
decomposition of N2O5
in the reaction 2 N2O5(g) ‐> 4 NO2(g) + (g) is k = 3.38 x 10‐5 s‐
O2(g)
1 at 25°C. What is the half life of N2O5? What will be the pressure, initially 500 Torr, after (a) 10 s, (b) 10 min after initiation of the reaction?
5/12/2008
2
22.5a
•
5/12/2008
HW5 solutions
HW5 solutions
5
5/12/2008
HW5 solutions
6
1
5/12/2008
22.14a
P 22.16
• The rate constant for the decomposition of a certain substance is 2.80 x 10‐3 dm3 mol‐1 s‐1 at 30°C and 1.38 x 10‐2 dm3 mol‐1 s‐1 at 50°C. Evaluate the Arrhenius parameters of the reaction.
5/12/2008
HW5 solutions
7
•
The second‐order rate constants for the reaction of oxygen atoms with aromatic hydrocarbons have been measured (R. Atkinson and J.N. Pitts, J. Phys. Chem. 79, 295 (1975)) In the reaction
295 (1975)). In the reaction with benzene the rate constants are 1.44 ´ 107 dm3
mol‐1 s‐1 at 300.3 K, 3.03 x 107 dm3 mol‐1 s‐1 at 341.2 K, and 6.9 x 107 dm3 mol‐1 s‐1 at 392.2 K. Find the pre‐exponential factor and activation energy of the reaction.
5/12/2008
P 22.22
HW5 solutions
8
Simulation
• Derive an integrated expression for a second‐order rate law v = k[A][B] for a reaction of stoichiometry 2 A + 3 B ‐> P.
5/12/2008
HW5 solutions
9
• See Zhenfei’s solution.
5/12/2008
HW5 solutions
10
2