Chemical Reaction Engineering & Unit Operations Economics Flashcards
(20 cards)
A multiple effect evaporator produces 10,000 kg of salt from a 20% brine solution per day. One kg of steam evaporates 0.7 N kg of water
in N effects at a cost of P25 per 1000 kg of steam. The cost of the first effect is P450,000 and the additional effects at P300,000 each.
The life of the evaporator is 10 year with no salvage value. The annual average cost of repair and maintenance is 10% and taxes and
insurance is 5%. The optimum number of effects for minimum annual cost is
A. 3 effects B. 5 effects C. 4 effects D. 2 effects
A. 3 effects
The material cost at erection site for a 10,000 bbl/stream day vacuum distillation unit is P600000. Estimate the cost of a similar unit with a
capacity of 30,000 bbl/stream day?
A. P715,300 B. P1,180,000 C. P890,650 D. P934,200
B. P1,180,000
An organic chemical is produced by a batch process. In this process chemical X and Y react to form Z. Since the reaction rate is very
high, the total time required per bath has been found to be independent of the amount of materials and each batch required requires 2 hr,
including time for charging, heating and dumping. The following equation shows the relation between the pound of Z produced (lbz.) and
the pound of X (lbx) and Y (lby) supplied:
Lbz = 1.5(1.1lbxlbz + 1.3 lbylbz-lbx lby)0.5
Chemical X costs P0.09 per pound, chemical Y costs P 0.04 per pound and chemical Z sell for P0.8 per pound. If half of the selling price
for chemical Z is due to cost other than raw materials, the maximum profit obtainable per pound of chemical Z is
A. P0.3 per lbz B. P0.5 per lbz C. P0.12 per lbz D. P0.25 per lbz
C. P0.12 per lbz
The rate of formation of B in terms of rA (where rA=kCACB2) is
A. 1/2rA B. rA C. 2rA D. -1/2rA
C. 2rA
What is the reaction rate constant, K, for third order reaction?
A. (L/mol)/s B. (L/mol)/s2
C. (L/mol)2/s D. (L/mol)3/s
C. (L/mol)2/s
Consider the reaction 2H2 + O2 2H2O. What is the ratio of the initial rate of appearance of water to the initial rate of disappearance of oxygen?
A. 1:1 B. 2:1 C. 2:2 D. 3:2
B. 2:1
The net rate of reaction of an intermediate is
A. 0 B. 2 C. >0 D. <0
A. 0
A catalyst can
A. shift the equilibrium reaction
B. increase the rate constant of the forward reaction
C. diminish the activation energy
D. decrease the pressure
C. diminish the activation energy
A pressure cooker reduces cooking time because ______.
A. The heat is more evenly distributed
B. The boiling point is elevated
C. The higher pressure tenderizes the food
D. A large flame must be used
B. The boiling point is elevated
What is the order of the reaction wherein the half-life increases as the initial concentration increases?
A. 1st order B. zero order C. 2nd order D. 3rd order
B. zero order
Catalyst is a substance which
A. Increase the speed of chemical reaction
B. Decrease the speed of chemical reaction
C. Can either increase or decrease the speed of chemical reaction
D. Alters the value of equilibrium constant in a reversible reaction
C. Can either increase or decrease the speed of chemical reaction
For the reaction 2A(g) + 3B(g) D(g) + 2E(g) with rD= kCACB2 the reaction is said to be
A. non-homogeneous
B. elementary
C. non-elementary
D. consecutive
C. non-elementary
It is the amount of energy in excess of the average energy level which the reactants must have in order for the reaction to proceed.
A. bond energy B. activation energy C. free energy D. heat energy
B. activation energy
A reaction A 3B is conducted in a constant pressure vessel. Starting with pure A, the volume of the reaction mixture increase 3 times in
6 minutes. The final conversion is
A. 0.33
B. 1
C. 0.50
D. Data insufficient, can’t be predicted
B. 1
A gas decomposition reaction has an activation energy of 245 kJ/mol. The rate of the reaction can be accelerated by using a platinum
catalyst where the activation energy for the resulting catalyzed reaction is lower at 136 kJ/mol. Using Arrhenius law and assuming the
frequency factor remains the same, the catalyzed reaction is faster than the original reaction by a factor of
A. over 100,000 but less than a million
B. over 20 million
C. over 100 but less than 200
D. over 2 but less than 3
B. over 20 million
A batch reaction 2D + E F has a conversion factor expressed by the equation r=0.24t0.5 where r = conversion factor based on the
reactant E; t = time in hours which ranges from 0.5 to 16 hours per batch depending upon the process variables. The average molecular
weight of the feed is 60 and a density of 1.4 g/cc. The feed consists of 2 kgmole of D and 1 kgmole of E. the charging, cleaning and
discharging time per batch is 2.5 hrs and the volume of the reactor is twice the volume of the feed. Assume 300 days per year and 12
hours operation/day. The volume of the reactor in liters is
A. 257 B. 275 C. 300 D. 527
A. 257
An optimum number of the effects for a given application is a function of the
A. capacity B. economy C. efficiency D. none of these
B. economy
A method of selecting alternates by the comparison of all the pertinent annual direct costs plus the capital recovery costs.
A. present worth method
B. pay-out time method
C. annual cost method
D. rate-of-return method
C. annual cost method
In economic balance in evaporation, the common variable is the number of effects, an increasing number of which ____ the fixed costs.
A. increases
B. does not affect
C. decrease
D. may increase or decrease
A. increases
It is measure of profitability defined as the annual profit before taxes, divided by the fixed-capital investment.
A. return on investment B. payback period C. annual return D. present worth
A. return on investment
