The University of Western Australia Chemical and Process Engineering CHPR 3432 Chemical Kinetics and

Reactor Designs Tutorial 1

1. Classify the following reactions into elementary and non-elementary reaction (Note these reactions in reality may follow the rate laws given): a)

[ ]522252 42

ONkrateONOON

=

+

b)

[ ] [ ]222 )(2)()(2

ClNOkrategNOClgClgNO

=

+

c)

krategHgNgNH PtC

o

=

+ )(3)()(2 22,8563

d)

[ ][ ]

=

++

OHCOOCHCHkrateOHCHCOOCHOHCOOCHCH

33

3333

e)

[ ][ ]222

252 )(2)()(2NOOkrate

gNOgOgNO Co

=

+

f)

[ ]==

krate

CHCHCH 23

g) )(3)(3)(6)(5)( 223 lOHaqBraqHaqBraqBrO +++ +

What is the reaction order with respect to each reactant component and the overall order for each reaction.

2. What is the unit of the rate constant for a) a zero order, b) a first order and c) a second order.

3. Explain briefly the dependence of rate constant upon activation energy E ( use Arrhenius Law) ?

4. The rate of the second-order decomposition of acetaldehyde ( )CHOCH 3 was measured over the temperature range 700-1000K, and the rate constants are reported below. Find the activation energy E and the pre-exponential factor

ok .

KT / 700 730 760 790 810 840 910 1000 )../( 11 smolLk 0.011 0.035 0.105 0.343 0.789 2.17 20.0 145.0

(ans: ).184,..103.5 11111 == molkJEsmolLxko

5. The irreversible reaction

BABA 22 + has been studied kinetically, and the rate of formation of product has been found to be well correlated by the following rate equation:

[ ] [ ][ ]A

BAr BA 21

72.0 22 +

=

What reaction mechanism is suggested by this rate expression if the chemistry of the reaction suggests that the intermediate consists of an association of reactant molecules and that a chain reaction does not occur?

[ ][ ][ ]23 += HBrBrOkrate