Chemical Reaction Engineering Multiple Choice Questions & Answers on “Autocatalytic Reactions”.
1. Autocatalytic reactions are the ones in which ____
A. One of the products poisons the catalyst
B. There is no catalyst employed
C. Only one reactant is involved
D. One of the products catalyses the reaction
View Answer
Answer: D
Explanation: In autocatalytic reactions, the reactant is catalyzed by a product. One of the products is also a reactant.
2. State true or false.
An autocatalytic reaction is represented as A + R → R + R where, A is a reactant and R formed as the product catalyses the reaction.
A. True
B. False
View Answer
Answer: A
Explanation: Initially, the progress of the reaction requires more R. As the reaction proceeds, A is consumed. Hence, more of A is required for the reaction to occur as time proceeds.
3. State true or false.
Autocatalytic reactions are single order reactions.
A. True
B. False
View Answer
Answer: B
Explanation: The rate expression for autocatalytic reactions is non linear. In the reaction A + R → R + R, the concentration of R has to be initially increased. The concentration of R should be decreased as reaction progresses to favour product formation.
4. An example of autocatalytic reaction is ____
A. Ammonia formation reaction
B. Hydrogen peroxide decomposition reaction
C. Reaction of permanganate with oxalic acid
D. Oxidation of copper
View Answer
Answer: C
Explanation: Permanganate in acidic medium oxidises the oxalic acid. This reaction produces Mn2+ ions, which in turn catalyses the reaction.
6. If the area under the curve of (frac{1}{-r_A} ) versus XA for a PFR used to carry out an autocatalytic reaction is 5((frac{m^3 s}{mol}),) then the ratio of change in volume to molar feed rate is ____
A. 5
B. 10
C. 15
D. 20
View Answer
Answer: B
Explanation: For a PFR,
FA0dXA=(-rA)dV
The area under the curve of (frac{1}{-r_A} )versus XA = (frac{dXA}{(-rA.} = frac{dV}{F_{A0}}) = 5.
7. Which of the following reactors is used for carrying out autocatalytic reactions?
A. CSTR
B. PFR
C. Batch reactor
D. A combination of CSTR and PFR.
View Answer
Answer: D
Explanation: A combination of reactors is used to optimize the reactor volume. The reactors are arranged such that the required conversion is achieved. The volume should be low due to economic considerations.
9. The autocatalyst in microbial fermentation reactions is:
A. Organic feed
B. Microbes
C. Enzyme
D. Product chemical
View Answer
Answer: B
Explanation: The microbes act on the organic feed to produce the product and more microbial cells. In microbial fermentation, the microbe which acts as the catalytic agent reproduces itself.