MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar

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1. For a second-order reaction, what is the unit of the rate of the reaction?
a) s-1
b) mol dm-3s-1
c) mol-1 dm s-1
d) mol-2 dm-6 s-1
2. The rate constant of a reaction is k=3.28 × 10-4 s-1. Find the order of the reaction.
a) Zero order
b) First order
c) Second order
d) Third order
3. For a reaction A +B → C, the experimental rate law is found to be R=k[A]1[B]1/2. Find the rate
of the reaction when [A] = 0.5 M, [B] = 0.1 M and k=0.03.
a) 4.74 × 10-2 (dm3/mol)1/2 s-1
b) 5.38 × 10-2 (dm3/mol)1/2 s-1
c) 5.748 × 10-2 (dm3/mol)1/2 s-1
d) 4.86 × 10-2 (dm3/mol)1/2 s-1
4. The reaction NO2 + CO → NO + CO2 takes place in two steps. Find the rate law.
2NO2 → NO + NO3 (k1) – slow
NO3 + CO → CO2 + NO2 (k2) – fast
a) R = k1 [NO2]3
b) R = k2 [NO3] [CO]
c) R = k1 [NO2]
d) R = k1 [NO2]2
5. For the reaction A + H2O → products, find the rate of the reaction when [A] = 0.75 M, k= 0.02.
a) 0.077 s-1
b) 0.085 s-1
c) 0.015 s-1
d) 0.026 s-1
6. What is the rate law for acid hydrolysis of an ester such as CH3COOC2H5 in aqueous
solution?
a) k [CH3COOC2H5]
b) k [CH3COOC2H5] [H2O]
c) k [CH3COOC2H5]2
d) k

7. What is the concentration of the reactant in a first order reaction when the rate of the
reaction is 0.6 s-1 and the rate constant is 0.035?
a) 26.667 M
b) 17.143 M
c) 26.183 M
d) 17.667 M

PREPARED AND COMPILED BY: ENGR. HAFIZ MUHAMMAD SAAD WAQAR

MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar
CHEMISTRY CHEMICAL KINETICS - TPP

8. How many times will the rate of the elementary reaction 3X + Y → X2Y change if the
concentration of the substance X is doubled and that of Y is halved?
a) r2= 4.5r1
b) r2= 5r1
c) r2= 2r1
d) r2= 4r1
9. Which of the following reactions is an example of a pseudo first-order reaction?
a) H2 + Br2 → 2HBr
b) CH3CHO → CH4 + CO
c) C12H22O11 + H2O → glucose + fructose
d) PCl5 → PCl3 + Cl2
10. The rate law for inversion of cane sugar is R=k [C12H22O11][H2O]. Find the concentration of
sucrose if the rate of the reaction is 0.032 s-1 and rate constant k=0.005.
a) 5.8 M
b) 6 M
c) 6.2 M
d) 6.4 M
11. Which of the following is not true for a pseudo first-order reaction?
a) The reaction follows first order kinetics
b) Molecularity of the reaction should be one
c) The reactants such as water are present in excess and are assumed to be constant throughout
the reaction
d) Unit of the rate constant is s-1
12. Which of the following is not similar between a first order and pseudo first order reaction?
a) The molecularity is one in both the reactions
b) Both follows first order kinetics
c) The unit of rate constant is s-1
d) The rate of the reaction depends only on one reactant

13. Molecularity is ___________ value and order is ___________ value.

a) an integer, a fractional
b) a fractional, an integer
c) both fractional
d) both integers
14. Reaction corresponding to stoichiometric equation is called __________
a) Non-elementary
b) Elementary
c) Heterogeneous
d) Homogeneous
15. The rate constant for a first order reaction depends on _____________
a) Pressure
b) Temperature

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MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar
CHEMISTRY CHEMICAL KINETICS - TPP

c) Concentration
d) Time
16. The factors affecting the rate of homogeneous reaction are ____
a) Temperature only
b) Pressure only
c) Reactant Concentration only
d) Temperature, pressure and reactant concentration
17. Order of a reaction is ____
a) Number of molecules of reactants taking part in the reaction
b) Power of any one of the reactant concentrations
c) Concentration of intermediate species formed
d) Sum of the powers of the concentrations of all the reactant
18. Reaction kinetics deals with the study of ___________
a) Rate of reaction
b) Mechanism of reaction
c) Factors which affects the rate of reaction
d) All of the mentioned
19. The reaction rate is defined as the rate at which the concentration of the reactants
__________ with time or the concentration of products ___________ with time.
a) Increase, increase
b) Decrease, decrease
c) Decrease, increase
d) Increase, decrease

20. The reaction rate constant may be defined as the rate of the reaction when the
concentration of each reactants is ___________
a) Zero
b) Unity
c) Doubled the initial concentration
d) Infinite

21. The unit s-1 is the unit of rate constant for the reaction of the order is?
a) 1
b) 2
c) 0.5
d) 0

22. What will be the order of reaction if the rate law is given by ___________
Rate = k [SO2]1 [SO3]-0.5
a) 1
b) 0.5
c) 2
d) -0.5

PREPARED AND COMPILED BY: ENGR. HAFIZ MUHAMMAD SAAD WAQAR

MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar
CHEMISTRY CHEMICAL KINETICS - TPP

23. Which of the following will lead to an increase in the rate of the reaction?
a) Decrease in temperature
b) Decreasing concentration of reactants
c) Addition of catalyst
d) Addition of inhibitor

24. Which of the following laws state that the rate of a chemical reaction is directly proportional
to the concentration of reactants?
a) Henry’s law
b) Law of conservation of mass
c) Law of mass action
d) Dalton’s law

25. What is the change in the rate of a second order reaction when the concentration of the
reactant is increased by 2 times its initial value?
a) It doubles
b) No change
c) It quadruples
d) It triples

26. When the two reactants are in the same phase, then which common phase will ensure that
the products are formed at the fastest pace?
a) Solid
b) Liquid
c) Gas
d) The rate of a reaction is independent of the phase of the reactants

27. Temperature dependence of reaction rates can be studied by plotting a graph between
___________
a) Concentration of reactants and temperature
b) Concentration of products and temperature
c) Rate constant and temperature
d) Rate of catalysis and temperature

28. According to Arrhenius equation, rate constant(k) is proportional to ___________

a) Activation Energy (E)
b) eE
c) e1/E
d) e-E

29. A zero order reaction is one ___________

a) In which rate is independent of reactants concentration
b) In which one of the reactant is in large excess
c) Whose rate is not affected by time
d) Whose rate increases with time

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MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar
CHEMISTRY CHEMICAL KINETICS - TPP

30. Hydrogenation of oil is an example of ___________ reactor

a) Homogeneous
b) Heterogeneous
c) Autocatalytic
d) Insufficient data

MC ANSWE
EXPLANATION
Q R
The unit of the rate of the reaction (k) is (mol L-1) 1-n s-1, where n is the order of the reaction.
1 c For a second-order reaction, n=2.
(mol L-1) 1-n s-1 = (mol L-1)1-2 s-1 = mol-1 L s-1.

Given,
k= 3.28 × 10-4 s-1
2 b The general formula to find the units for rate constant, k=(mol L-1)1-ns-1 where n is the order of the
reaction. The value of n must be 1 for (mol L-1)1-ns-1 to become s-1. Therefore, k=3.28 × 10-4s-1
represents a first order reaction.

3 a

In any reaction the slowest step is the rate determining step, the rate of the overall reaction depends on
4 d this step. So, 2NO2 → NO + NO3(k1) is the rate determining step. Therefore the rate law R= k 1[NO2]2.

Given,
[A] = 0.75 M, k= 0.02
5 c The reaction belongs to pseudo first order reaction so, the unit is s-1
R= k [A]= 0.02 × 0.75= 0.015 s-1.

6 a this is pseudo first order reaction.

Explanation: Given, R=0.6 s-1 and k= 0.035

7 b For a first order reaction R= k [A]
[A]=Rk = 0.60.035 = 17.143 M.

PREPARED AND COMPILED BY: ENGR. HAFIZ MUHAMMAD SAAD WAQAR

MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar
CHEMISTRY CHEMICAL KINETICS - TPP

Since it is an elementary reaction, its rate law r1= k [A] 3[B]

8 d When the concentrations are changed the new rate will be r2= k (2[A])3([B]/2) = 4k[A]3[B]
So, r2=4r1.

The order of the reaction may be sometimes altered sometimes by changing the conditions, for example,
9 c taking one or more reactants in excess compared to the other. The molecularity of inversion of cane sugar
is 2 but follows first order kinetics because water is present in excess.

Given, rate constant k=0.005, rate of the reaction R=0.032 s -1.

Inversion of cane sugar is a pseudo first order reaction and water is present in large excess so the rate
law becomes R=k [C12H22O11]
10 d 0.032= 0.005 [C12H22O11]
[C12H22O11]=6.4 M.

The order of the reaction can be sometimes altered by taking one of the reactant in excess compared to
11 b the other. Pseudo first order reactions are those reactions in which the molecularity is more than one but
follows first order kinetics.

Both first order and pseudo first order reactions follow first order kinetics as in the rate of the reaction
depends only on one reactant and the unit for rate constant is s -1 but the molecularity in first order
12 a reaction should be one where as in pseudo first order reaction the molecularity can be more than one. For
example: Inversion of cane sugar.

Order is empirical, hence can be a fractional value but molecularity refers to the mechanism and is
13 a applicable only for elementary reactions.

Elementary reactions are the ones with single reaction step and the reaction rate corresponds to
14 b stoichiometric equation.

15 b The reaction rate constant depends on temperature only.

The rate constant in the rate expression is a function of temperature. Increasing pressure decreases the
collisions between reactant molecules. This decreases the rate of reaction. Increasing the initial
16 d concentration of reactant increases the reaction rate. Hence, reaction rate is controlled by temperature
and pressure conditions and initial concentration of reactant.

The order of a reaction with respect to a given substance is the power to which its concentration term is
raised in the rate equation. If there is more than one reactant molecules involved in the reaction, then the
17 d order of the reaction is the sum of the powers of concentrations of all reacting species in the rate
expression.

Reaction kinetics deals with the study of rate of reaction, their mechanism and the factors which affects
18 d the rate of reaction. It specifies all the general characteristics of a chemical reaction.

The reaction rate is defined as the rate at which the concentration of the reactants decreases with time or
19 c the concentration of products increases with time.

The reaction rate constant may be defined as the rate of the reaction when the concentration of each
20 b reactants is unity. A reaction rate constant or reaction rate coefficient, k, quantifies the rate of a chemical
reaction.

PREPARED AND COMPILED BY: ENGR. HAFIZ MUHAMMAD SAAD WAQAR

MathsflixByHashimZia PhysicsKaManjan ChemistryBySaadWaqar
CHEMISTRY CHEMICAL KINETICS - TPP

The unit s-1 is the unit of rate constant for the reaction of the order zero. It quantifies the rate of a chemical
21 d reaction.

The order of the reaction will be 0.5. It is given by:

22 b Order = 1-0.5 = 0.5.

The presence of a catalyst in a reaction lowers the activation energy barrier and hence the reaction
23 c becomes faster. Hence, the addition of catalysts helps to increase the rate of a reaction.

The law of mass action is the proposition which states that the rate of a chemical reaction is directly
24 c proportional to the concentrations of the reactants. On the other hand, the other laws mentioned in the
options are unrelated to the rate of a reaction.

Let the initial concentration of reactant = [A]

Given concentration of reactant = 2 x [A]
We know that the rate of a second order reaction = k x [A]2
25 c Therefore, rate for 2 x [A] = k x 4 x [A]2
Therefore, the rate quadruples when the concentration of the reactant is doubled in a second order kinetic
reaction.a

When two reactants are in the same phase, it is better for the speed if the reaction if they are in a
26 c gaseous phase as the particles are free to move and can collide more frequently with each other,
resulting in a chemical reaction.

Temperature dependence of reaction rates can be studied by plotting a graph between rate constant and
27 c temperature for different reactions.

28 d

A zero order reaction is one in which rate is independent of reactants concentration. It only depends upon
29 a the rate constant.

The reactants are of different phases i.e. Hydrogen (Gas phase) and oil (Liquid phase). Ni catalyst (Solid)
30 b is also used.

PREPARED AND COMPILED BY: ENGR. HAFIZ MUHAMMAD SAAD WAQAR