1st Long Exam

00

Revision No.:

Revision Date: January 06, 2010

___1st___LONG EXAMINATION (CHE171 – Chemical Reaction Engineering1) GENERAL INSTRUCTIONS:  Use the standard MCL test booklet only.  Borrowing of exam materials such as calculator, pens, etc. while taking the test is NOT permitted.  For problem based-item (part II), show complete solutions on your test booklet clearly. Indicate by enclosing in an box the final answers with appropriate units. Learning Outcome Codes

LO4

I. Multiple Choice. Write the letter of the answer.

1. The unit of k for a second order elementary reaction is a.

LO7

1/time b. concentration/time

)-1

d. (concentration (time)

c. 1/concentration

-1

2. The E of a reaction may be lowered by a.

LO3

adding a catalyst b. increasing temperature products

c. decreasing temperature

d. removing the

3. The mechanism of a reaction can sometimes be deduced from a. LO3

The net equation b. the rate law c. the temperature dependency of the rate d. energy

activation

4. The law governing the kinetics of a reaction is the law of a. LO3

a. LO3-4

c. mass action

d. chemical equilibrium

2

b. 4

c. 8

d. 16

Heat of reaction b. temperature

c. time of reaction

d. concentration of reactants

7. The rate of reaction is not influenced by a.

LO3-4

b. constant composition

6. The specific rate of reaction is primarily dependent on a.

LO3-4

constant temperature

5. If the volume of a container is suddenly reduced to ½ its original volume, the rate will increase by a factor of

Molecularity of the reaction temperature

b. concentration of reactants

c. nature of reactants

8. If the rate of reaction is independent of the concentration of the reactants, the reaction is said to be a.

First order

b. second order c. third order

d. zero order

LO2

9. For the reaction 2A(g) +3C(g) D(g) + 2E(g) with rD = kCACB2, the reaction is said to be

LO2

10. Chemical reaction rates in solution do not depend to any extent upon

a. a. LO3-4 LO3-4 LO7

LO4 LO5 LO2

LO3,5

LO3

d.

non-homogeneous concentration

b. non-elementary b. pressure

c. elementary

d. no reaction

c. temperature

d. catalyst

2

11. The rate of formation of B in terms of rA ( where rA = -kCACB ) is a. 2rA b. -1/2rA c. ½ rA d. rA 12. The overall order of reaction for the elementary reaction A + 2B C is a.

3

b. 2

c. 1

d. 0

13. The collision theory of chemical reaction maintains that _______ a. A chemical reaction occurs with every molecular collision b. Reactions in the gas phase are always first order c. Reaction rates are of the order of molecular speeds d. Rate is directly proportional to the number of collisions per second 14. I f the reaction 2A B + C is second order, which of the following plots will give a straight line a. CA2 versus time b. log CA versus time c. 1/CA versus time d. CA versus time 15. The activation energy of a reaction can be obtained from the slope of a plot of a. k vs log T b. log k vs 1/T c. k vs log 1/T d. log k vs T 16. In a reaction, this is a substance that affects the rate of reaction but emerges from the process unchanged. a. Contaminant b. catalyst c. reactant d. product

17. For the reaction A + B 2C, when CA is doubled the rate doubles when CB is doubled the rate increases four fold. The rate law is a. –rA = kCA2CB4 b. –rA = kCB2 c. –rA = kCACB2 d. –rA = kCA 18. It states that the rate of chemical reaction is proportional to the activity of the reactants a. Law of Mass Action b. Le Chatelier’s Principle c. Hess’s Law d. Second Law of Thermodynamics Prepared By/ Date (Faculty Member) Engr. JOSEPH R. ORTENERO

Reviewed By/ Date (Program Chair/Dean) Engr. MARIBEL G. SONGSONG

Page 1 of 2 FORM OVPAA-015A

00

Revision No.:

Revision Date: January 06, 2010

LO2

LO5

19. The composition of the reaction component vary from position to position along a flow path in a/an a. Batch reactor b. Adiabatic reactor c. CSTR d. Plug flow reactor 20. A certain reaction is second order in A, when CA is 0.03 mol/L, the rate is 3 x 10-3 L/mol-s. The rate when CA is 0.015 mol/L in L/mol-s is -4 -3 a. 0.21 b. 7.5 x 10 c. 3.33 d. 1.5 x 10 PROBLEM SOLVING: (15 PTS EACH)

LO7

1. The liquid phase hydrolysis of dilute aqueous acetic anhydride solution (CH3CO)2O +H2O H2O + 2CH3COOH is second order irreversible. Our data on rates as a function of temperature were T°C Rate (gmol/cm3-min)

10 0.0567C

15 0.0806C

25 0.158C

40 0.380C

Where C = acetic anhydride concentration in gmol/cm3. What is the value of the Arrhenius constant? LO10

2. A 70% by weight trichloroacetic acid in aniline is reacted in a 1275 L batch reactor for 36 hours at 50°C to produce CHCl3 as per the following reaction

Calculate the amount of chloroform produced in metric tons (MT) per 7-day week (3 shifts daily) allowing 6 hours pumping time per batch. The first order rate constant is 8 x 10-4/min at the temperature of the reaction. Sp gr of the feed is 1.5. LO10

3. The reaction between ethylene bromide and potassium iodide in 99% methanol inert has been found to be first order with respect to each reactant (second order overall)(Dillon, 1932). The reaction can be represented by C2H4Br2 + 3KI → C2H4 +2KBr + KI3 or A +3B → products. (a) Derive an equation for calculating the second order rate constant kA. (b) At 59.7°C in one set of experiments for which CAO = 0.0266 and CBO = 0.2237 mol/L, the bromide was 59.1% reacted at the end of 15.25 h. Calculate the value of k and specify its units.

LO7

4. Rate constants for the first-order decomposition of nitrogen pentoxide (N205) at various temperatures are as follows (Alberty and Silbey, 1992, p. 635): T/K 105 /s-1

273 298 0.0787 3.46

308 13.5

318 49.8

328 150

338 487

Show that the data obey the Arrhenius relationship, and determine the values of the Arrhenius parameters.

Prepared By/ Date (Faculty Member) Engr. JOSEPH R. ORTENERO

Reviewed By/ Date (Program Chair/Dean) Engr. MARIBEL G. SONGSONG

Page 2 of 2 FORM OVPAA-015A