Page 300 - Elements of Chemical Reaction Engineering 3rd Edition

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272 Collection and Analysis of Rate Data Chap. 5

(c) What experimental conditions would you suggest if you were to obtain
more data?
(d) How would the data and your answers change if the reaction were run at
a higher or lower temperature?
P5-88 In order to study the photochemical decay of aqueous bromine in bright sun-
light, a small quantity of liquid bromine was dissolved in water contained in
a glass battery jar and placed in direct sunlight. The following data were
obtained:

Time (min) 1 10 20 30 40 50 60
ppm Br, 1 2.45 1.74 1.23 0.88 0.62 0.44

temperature = 25°C
(a) Determine whether the reaction rate is zero, first, or second order in bro-
mine, and calculate the reaction rate constant in units of your choice.
(b) Assuming identical exposure conditions, calculate the required hourly
rate of injection of bromine (in pounds) into a sunlit body of water,
25,000 gal in volume, in order to maintain a sterilizing level of bromine
of 1.0 ppm. (Ans.: 0.43 lb/h)
(c) What experimental conditions would you suggest if you were to obtain
more data?
(Note: pprn = parts of bromine per million parts of brominated water by
weight. In dilute aqueous solutions, 1 ppm =_ 1 milligram per liter.) (Califor-
nia Professional Engineers Exam)
P5-9, The gas-phase decomposition
A --+ B+2C

is carried out in a constant-volume batch reactor. Runs 1 through 5 were car-
ried out at 100°C while run 6 was carried out at 110°C.
(a) From the data in Table P5-9, determine the reaction order and specific
reaction rate.
(b) What is the activation energy for this reaction?

TABLE P5-9 RAW DATA
Initial Concentration, C,, Half-Life, tm
' Rut7 (g molAJ (min)
1 0.0250 4.1
2 0.0133 7.7
3 0.0 10 9.8
4 0.05 1.96
5 0.075 1.3
6 0.025 2.0

P5-10, The reactions of ozone were studied in the presence of alkenes [R. Atkinson
et al., Int. J. Clzem. Kinet., 15(8), 721 (1983)]. The data in Table P5-10 are for
one of the alkenes studied, cis-2-butene. The reaction was carried out isother-
mally at 297 K. Determine the rate law and the values of the rate law parameters.