Page 41 - Introduction to chemical reaction engineering and kinetics

1.8 Problems for Chapter 1 23

(d) {(H+, OH-, NO+, Tl+, H20, NO;, N203, HN02, TlNOz), (H, 0, N, Tl, p)} relating to the
complexation of Tl+ by NO; in aqueous solution (Cobranchi and Eyring, 1991). (Charge
p is treated as an element.)
(e) {(C~I-IJ, C&, CdHs, CsHis, CbHtz), (C, H)} relating to the oligomerization of CzI&.
(f) {(ClO;, HsO+, Cls, H20, ClO;, ClOz), (H, Cl, 0, p)} (Porter, 1985).
1-5 The hydrolysis of a disaccharide, CizH2sOii(A)+H20 + 2c6H1206, takes place in a constant-
volume 20-L container. Results of the analysis of the concentration of disaccharide as a function
of time are:

tls 0 5 10 15 20 30 40 50
cA/molL-’ 1.02 0.819 0.670 0.549 0.449 0.301 0.202 0.135

(a) What is the relationship between the rate of disappearance of disaccharide (A) and the rate
of appearance of monosaccharide (CsHi206)?
(b) For each time interval, calculate the rate of disappearance of disaccharide (A), in terms of
both the total or extensive rate, (-RA), and the volumetric or intensive rate, (-TA).
(c) Plot the rates calculated in (b) as functions of CA. What conclusions can you draw from this
plot?
1-6 In a catalytic flow reactor, CO and H:! are converted to CHsOH.
(a) If 1000 kg h-l of CO is fed to the reactor, containing 1200 kg of catalyst, and 14% of CO
reacts, what is the rate of methanol production per gram of catalyst?
(b) If the catalyst has 55 m2 g-’ surface area, calculate the rate per m2 of catalyst.
(c) If each m2 of catalyst has 1019 catalytic sites, calculate the number of molecules of methanol
produced per catalytic site per second. This is called the turnover frequency, a measure of
the activity of a catalyst (Chapter 8).
1-7 The electrode (or half-cell) reactions in a Hz-02 fuel cell are:
Hz(g) + 2H+(aq) + 2e (anode)

02(g) + 4H+(aq) + 4e + 2H20(9 (cathode)

If a battery of cells generates 220 kW at 1.1 V, and has 10 m2 of Pt electrode surface,
(a) What is the rate of consumption of HZ, in mol m-* s-l?
(b) What is the rate of consumption of 02?
(NA” = 6.022 X 1O23 mol-‘; electronic charge is 1.6022 X lo-l9 C)
1-8 At 7 A.M., the ozone (0s) content in the atmosphere over a major city is 0.002 ppmv (parts per
million by volume). By noon, the measurement is 0.13 ppmv and a health alert is issued. The
reason for the severity is that the region acts as a batch reactor-the air is trapped horizontally
(by mountains) and vertically (by a temperature inversion at 1000 m). Assume the area of the
region is 10,000 km* and is home to 10 million people. Calculate the following:
(a) The average intensive rate, $, during this period, in mol me3 SK’;
(b) The average extensive rate, Ro,, during this period; and
(c) i=03 in mol person-’ h-l.
(d) If the reaction is 302 + 203 (A), calculate (--a,) and ?(A).
1-9 The destruction of 2-chlorophenol (CP, M = 128.5 g mall’), a toxic organochlorine compound,
by radiative treatment was investigated by Evans et al. (1995). The following data were mea-
sured as a function of time in a 50 cm3 closed cell:

t/h 0 6 12 18 24
ccplmg L-l 0.340 0.294 0.257 0.228 0.204

(a) What is (-rep) in mol L-’ se1 during the first time interval?
(b) What is (-rep) in mol L-l s-l during the last time interval?