Page 102 - Introduction to chemical reaction engineering and kinetics

84 Chapter 4: Development of the Rate Law for a Simple System

(a) Calculate the corresponding values of & in kPaa2s-‘.
(b) Determine the values of the Arrhenius parameters based on the values of ka given above.
(c) Repeat (b) using the values calculated in (a) to obtain EAT and A,,.
(d) Compare the difference EA - E.+, as calculated in (b) and (c) with the expected result.
(e) Which is the better representation, (b) or (c), of the experimental data in this case?
(See also data of Bodenstein et al. (1918,1922), and of Greig and Hall (1967) for additional
data for the range 273 to 622 K).
4-13 The chlorination of dichlorotetramethylbenzene (A) in acetic acid at 30°C has been studied
by Baciocchi et al. (1965). The reaction may be represented by

A + B + products,

where B is chlorine. In one experiment in a batch reactor, the initial concentrations were CA0 =
0.0347 mol L-l, and caO = 0.0192 mol L-‘, and the fraction of chlorine reacted (fa) at various
times was as follows:

tlmin 0 807 1418 2255 2855 3715 4290
fB 0 0.2133 0.3225 0.4426 0.5195 0.5955 0.6365
Investigate whether the rate law is of the form (-7~) = (-ra) = kcAcB, and state your con-
clusion, including, if appropriate, the value of k and its units.
4-14 The reaction 2N0 + 2Hz + N2 + 2HzO was studied in a constant-volume BR with equimolar
quantities of NO and HZ at various initial pressures:

P,lkPa 47.2 45.5 50.0 38.4 33.5 32.4 26.9
t112ls 81 102 95 140 180 176 224
Calculate the overall order of the reaction (Moore, 1972, p. 416).
4-15 The hydrolysis of ethylnitrobenzoate by hydroxyl ions

N02C6H4COOC2Hs + OH- + NO&J-LCOO~ + CzHsOH

proceeds as follows at 15°C when the initial concentrations of both reactants are 0.05 mol L-’
(constant-volume batch reactor):

tls 120 180 240 330 530 600
% hydrolyzed 32.95 41.75 48.8 58.05 69.0 70.4

Use (a) the differential method and (b) the integral method to determine the reaction order,
and the value of the rate constant. Comment on the results obtained by the two methods.
4-16 The kinetics of the gas-phase reaction between nitrogen dioxide (A) and trichloroethene (B)
have been investigated by Czarnowski (1992) over the range 303-362.2 K. The reaction ex-
tent, with the reaction carried out in a constant-volume BR, was determined from measure-
ments of infrared absorption intensities, which were converted into corresponding pressures
by calibration. The products of the reaction are nitrosyl chloride, NOCl (C), and glyoxyloxyl
chloride, HC(O)C(O)Cl.
In a series of seven experiments at 323.1 K, the initial pressures, PA0 and Pno, were varied,
and the partial pressure of NOCl, PC, was measured after a certain length of time, t. Results
are as follows:

t/mm 182.2 360.4 360.8 435.3 332.8 120.0 182.1
pAofl<Pa 3.97 5.55 3.99 2.13 3.97 2.49 2.08
pBoma 7.16 7.66 6.89 6.77 3.03 8.57 9.26
p&Pa 0.053 0.147 0.107 0.067 0.040 0.027 0.040