10 Chemical Kinetics Quiz | Chemistry Quiz
In this Chemistry quiz article, we are going to share some Chemistry study material and some multiple-choice questions of solution chapter which having some topics like Rate of a reaction, Rate law and Rate constant, Collision theory, Energy of activation and Arrhenius equation..
The branch of physical chemistry which deals with the rate at which the chemical reactions occur, the mechanism by which the chemical reactions take place and the influence of various factors such as concentration, temperature, pressure, catalyst, etc., on the reaction rates is called the chemical kinetics.
Types of chemical reactions
On the basis of reaction rates, the chemical reactions have been classified into the following three types,(1) Very fast or instantaneous reactions: These reactions occur at a very fast rate generally these reactions involve ionic species and known as ionic reactions. It is almost impossible to determine the rates of these reactions.
Rate of a Reaction Quiz
1. If the concentration of the reactants is increased, the rate of reaction(a) Remains unaffected
(b) Increases
(c) Decreases
(d) May increase or decrease
SOL: (b) Greater are the concentrations of the reactants, faster is the reaction. Conversely, as the concentrations of the reactants decreases, the rate of reaction also decreases.
2. Time required for completion of ionic reactions in comparison to molecular reactions is
(a) Maximum (b) Minimum
(c) Equal (d) None
SOL: (b)Ionic reactions are very fast reactions i.e. take place instantaneously.
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3. For reaction 2A+B -> products, the active mass of B is kept constant and that of A is doubled. The rate of reaction will then
(a) Increase 2 times
(b) Increase 4 times
(c) Decrease 2 times
(d) Decrease 4 times
SOL: (b)
4. The rate of a chemical reaction depends upon
(a) Time (b) Pressure
(c) Concentration (d) All of these
SOL: D
5. When the concentration of A in the reaction A+B⇌AB is doubled, the rate of reaction will be
(a) Doubled
(b) Decreased by half
(c) Unchanged
(d) Increased by four times
SOL: A
6. The main function of a catalyst in speeding up a reaction is
(a) To increase the rate of the forward reaction
(b) To change the reaction path so as to decrease the energy of activation for the reaction
(c) To reduce the temperature at which the reaction can occur
(d) To increase the energy of the molecules of the reactants
SOL: (b) Catalyst decrease energy of activation.
7. The rate of a reaction
(a) Increases with increase in temperature
(b) Decreases with increase in temperature
(c) Does not depend on temperature
SOL: (a) Thus both rate and rate constant K increase with temperature,
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Rate law and Rate constant Quiz
8. Velocity constant K of a reaction is affected by
(a) Change in the concentration of the reactant
(b) Change of temperature
(c) Change in the concentration of the product
(d) None of the above
SOL: (b) Velocity constant ‘K’ is characteristic constant of a reaction and depends only on temperature and catalyst.
9. The velocity constant of a reaction is K. Which of the following statements is not true regarding K
(a) K is a constant for a reaction at a given temperature
(b) The value of K changes when the temperature changes
(c) K is the velocity of the reaction at unit concentrations of the reactant
(d) K is a constant for all reactions
SOL: (d) K is not constant for all the reaction.
10. The rate of reaction between and increases by a factor of 100, when the concentration of is increased 10 folds. The order of reaction with respect to A is
(a) 10 (b) 1
(c) 4 (d) 2
SOL: (d)
11. Which one of the following statements is wrong
(a) Molecularity of a reaction is always a whole number
(b) Order and molecularity of a reaction need not be same
(c) Order of a reaction may be zero
(d) Order of a reaction depends upon the mechanism of the reaction
SOL: (d) Order of reaction is an experimental value, while molecularity is a theoretical value.
12. The velocity constant of first order reaction is expressed in the units
(a) Concentration per unit time
(b) Time per unit concentration
(c) Per unit time
(d) Unit time per unit concentration
SOL: (c)K for 1st order reaction = per unit time
13. If the surface area of the reactants increases, then order of the reaction
(a) Increases
(b) Decreases
(c) Remain constant
(d) Sometimes increases and sometimes dereases
SOL: c
14. Molecularity of reaction of inversion of sugar is
(a) 3 (b) 2
(c) 1 (d) 0
SOL: (b) Inversion of sugar is a pseudo-unimolecular reaction.
15. For any reaction, if we plot a graph between time ‘t’ and log(a-x), a simple line is obtained. The order of reaction is
(a) Zero (b) One
(c) Two (d) Three
SOL: (b)
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Collision theory, Energy of activation and Arrhenius equation Quiz
16. According to the collision theory of chemical reactions(a) A chemical reaction occurs with every molecular collision
(b) Rate is directly proportional to the number of collisions per second
(c) Reactions in the gas phase are always of zero order
(d) Reaction rates are of the order of molecular speeds
SOL: (b) The increase in collision frequency brings in an increase in effective collisions and thus rate of reaction increases.
17. According to the collision theory of reaction rates, rate of reaction increases with temperature due to
(a) Greater number of collisions
(b) Greater velocity of the reacting molecules
(c) Greater number of molecules have activation energy
(d) None of the above
SOL: (c) The increase in collision frequency brings in an increase in effective collisions and thus rate of reaction increases.
18. The reaction rate at a given temperature becomes slower, then
(a) The free energy of activation is higher
(b) The free energy of activation is lower
(c) The entropy changes
(d) The initial concentration of the reactants remains constant
SOL: (a) Slower reaction rate indicates higher energy of activation.
19. According to Arrhenius theory, the activation energy is
(a) The energy it should possess so that it can enter into an effective collision
(b) The energy which the molecule should possess in order to undergo reaction
(c) The energy it has to acquire further so that it can enter into a effective collison
(d) The energy gained by the molecules on colliding with another molecule
SOL: (c) The definition of activation energy.
20. The energy of activation is
(a) The energy associated with the activated molecules
(b) Threshold energy – energy of normal molecules
(c) Threshold energy + energy of normal molecules
(d) Energy of products – energy of reactants
SOL: (b) Activation energy is the energy needed by reactant molecules to gain threshold energy level.
21. Activation energy of any reaction depends on
(a) Temperature
(b) Nature of reactants
(c) Number of collisions per unit time
(d) Concentration of reactants
SOL: (b) The value of activation energy for a chemical reaction primarily dependent on the nature of reacting species.
22. The rate constant of a reaction at temperature 200K is 10 times less than the rate constant at 400 K. What is the activation energy Ea of the reaction (R = gas constant)
(a) 1842.4 R (b) 921.2 R
(c) 460.6 R (d) 230.3 R
SOL: b
