Page 101 - Introduction to chemical reaction engineering and kinetics

4.5 Problems for Chapter 4 83

CHsCOONa + CsHsCH&I -+ CHsCOOC6HsCH2 + Na’ + Cl-

or A + B + products

Some of the data they obtained for a solution equimolar in reactants (CA0 = 0.757 mol L-l) in
a constant-volume batch reactor are as follows (fi; is the fraction of B unconverted at time t):
10-3tls 24.5 54.7 88.6 126.7
fr; 0.912 0.809 0.730 0.638
Determine the form of the rate law and the value of the rate constant at 102°C based on these
data.
4-8 The rate of decomposition of nitrogen pentoxide (NzOs) in the inert solvent CC14 can be fol-
lowed by measuring the volume of oxygen evolved at a given temperature and pressure, since
the unreacted NzOs and the other products of decomposition remain in solution. Some results
at 45°C from a BR are as follows (Eyring and Daniels, 1930):
tls 162 409 1721 3400 00
02 evolved/cm3 3.41 7.78 23.00 29.33 32.60
What is the order of the decomposition reaction (which for this purpose can be written as
N20s + Nz04 + ~OZ)? Assume the reaction goes to completion.
4-9 Rate constants for the first-order decomposition of nitrogen pentoxide (N205) at various tem-
peratures are as follows (Alberty and Silbey, 1992, p. 635):
T/K 273 298 308 318 328 338
lo5 k/s-’ 0.0787 3.46 13.5 49.8 150 487

v Show that the data obey the Arrhenius relationship, and determine the values of the Arrhenius
parameters.
0 7O-v 4-10 Rate constants for the liquid-phase, second-order, aromatic substitution reaction of 2-
chloroquinoxaline (2CQ) with aniline in ethanol (inert solvent) were determined at sev-
eral temperatures by Pate1 (1992). The reaction rate was followed by means of a conductance
cell (as a BR). Results are as follows:
TI”C 20 25 30 35 40
105k/dm3 mol-t s-t 2.7 4.0 5.8 8.6 13.0
Calculate the Arrhenius parameters A and EA for this reaction, and state the units of each.
4-11 Suppose the liquid-phase reaction A --z B + C was studied in a 3-L CSTR at steady-state, and
the following results were obtained:

v
yap:
0 4-12 The oxidation of nitric oxide, NO(A) + :O, -+ NOz, is a third-order gas-phase reaction
Assuming that the rate law is of the form (-rA) = kAct = A exp(-E,JRT)ci, determine A,
EA, and n, and hence kc at 25°C and at 35°C. CAM in all three runs was 0.250 mol L-‘.
(second-order with respect to NO). Data of Ashmore
at various temperatures are as follows: et al. (1962) for values of the rate constant
T/K 377 473 633 633 692 799
lo-3 kA/L’ mOl-2 S-l 9.91 7.07 5.83 5.73 5.93 5.71