Chemical Kinetics Questions and Answers

1000+ Chemical Kinetics Questions and Answers PDF

These Chemical Kinetics Questions and Answers PDF are prepared by our Livelearns team for NEET and JEE Mains. These Chemical Kinetics NEET Questions are based on the chapter on Chemistry Chemical Kinetics Preparation of these questions has been taken from various books including NCERT, Previous year’s question papers, and model papers. So these Chemical Kinetics JEE Questions cover all the class 12 subject chemistry topics of Chemical Kinetics, These MCQs are very helpful in your preparation for the National Eligibility cum Entrance Test-UG (NEET) and JEE mains. We have provided these questions in PDF format which you can Download by clicking the link as provide below. These Chemical Kinetics JEE Mains Questions PDF are absolutely FREE for you from Livelearns Team.

CHEMICAL KINETICS Questions and Answers PDF

  1. According to Arrhenius equation, rate of reaction increases with increase in temp. Give reasons.

Ans. With increase in temp. the kinetic energy of the molecules increases. So that number of effective collision increases giving more product. Hence rate of reaction increases.

  1. How is rate constant related to conc. of the reactant ?

Ans. Rate constant is independent of conc. of
reactant.

  1. Write two factors which influence the rate of reaction.

Ans. Concentration of reactant and tempeature.

4. What is the order of overall reaction ?

Ans. Order is deternmined from the slowest step. So order of the reaction is

  1. What is the unit of rate constant for 2nd order reaction ?

Ans. Mole–¹ lit sec–¹

  1. Calculate order of the reaction having rate expression, rate = K[A]2[B]3

Ans. Order = 3/2 + 1/2 = 2

  1. Give an example of zero order reaction.

Ans. Decomposition of ammonia giving nitrogen and hydrogen in presence of Pt–catalyst at 800° is an
example of zero order reaction.
2NH³ N²+ 3H²
Rate K [NH³] ⁰

  1. Express the rate of reaction for the reaction A, + 3B–→ 2AB³ in terms of reactants and products.

Ans. Rate of reaction
=dA²/dt = – 1/3 (d)B²/ dt=+ 1/2 d[AB³]/dt

  1. Define rate of reaction.

Ans. It is defined as the amount of reactant
Consumed or amount of product formed per unit time.

Rate of reaction=-(DX/dt) (w.r.t. reactant)= +(dx/dt) w. r.t. product)

  1. What is the relationship between activation energy and threshold energy ?

Ans. Eà= Eth-ER
Where Eà =activation energy of reactant
Eth= threshold energy
ER = average kinetic energy of reactant.

  1. Write the unit of rate of reaction.

Ans. mole lit–¹ sec–¹

  1. A substance with initial concentration 2M follows zero order kinetics with rate constant 2 x 10 M sec. How long will this reaction take to go to completion ?

Ans. We know K = x/t

Here x 2M, K = 2 x 10-2M sec

t=x/k{ 2m/ 2×10 M sec=100 sec

Hence it will take 100 sec for completion of the
reaction.

  1. The rate of reaction is doubled for every 10°C rise in temperature. If the temp is raised from 30°C to 70°C the rate of reaction will be increased by how many times ?

Ans. Rise in temperature 40°C
Rate of reaction will be, 24=16 times the initial rate.

  1. Inversion of Cane Sugar is an example of -order reaction.

Ans. Pseudofirst

  1. What is the relationship between rate constant and half life period of a 1st order reaction ?

Ans. t1/2=(0.693/k)
K = rate constant of the reaction.
half life period of the reaction.

  1. Activation energy for a chemical reaction depends upon.

Ans. Nature of reactant.

  1. For a 1st order reaction the time required for times, the time required 75% completion is – for 50% completion.

Ans. 2

  1. In all reactions increase in concentration of reactants increases rate of reaction. Yes or No.

Ans. No, in zero order reactions rate of reaction is independent of concentration of reactant.

  1. The unstable intermediate compound formed by reactants after absorption of activation energy is called as___

Ans. Activated complex

  1. Decomposition of H202 takes place in the following way

H2O,→ H20+0] x 2 (slow)

O+0- 02 (fast)

2H202→2H20+02
What is the order of overall reaction ?

Ans. Order is determined from the slowest step. So order of the reaction is 1.

  1. Write the integrated rate equation for a Znd order reaction of the type, 2A product.

Ans. K t a(a-x)
where K = rate constant.
a initial amount
X amount reacted at time t

22.What is the effect of temperature on activation energy?

Ans. There is no effect of temperature on activation
energy.

  1. Define rate constant of a reaction

Ans. It is a constant and equal to the rate of reaction
when concentration of the reactants is unity (l mole/litre).

  1. Hydrolysis of ester in presence of mineral acid is an example of order reaction.

Ans. Pseudo first order

  1. Alkaline hydrolysis of ester is an example of order reaction.

Ans. 2nd

  1. If unit of rate constant is mole lit’ sec-l order of the reaction is.

Ans. zero

  1. If for a reaction, the half life period is directly proportional initial concentration of reactant, what is the order of the reaction?

Ans. Zero order

  1. Write the Arrhenius equation Ea

Ans. K = Ae RT
Where K = rate constnat
A Collision number
Ea = activation energy
R 8.314 JK mole
T absolute temperature

  1. How does rate of reaction vary with activation energy ?

Ans. The reactions with smaller activation energy proceed faster and vice versa.

  1. How is heat of reaction related to activation energy ?

Ans. AH =E – E,
Where AH heat of reaction.
E activation energy for forward reaction.
E activation energy for backward reaction.

  1. What is the unit of rate constant for first order reaction?

Ans. Sec or minute

  1. What is activated complex?

Ans. It is the unstable transition state of the reactant with highest energy equal to threshold energy.

  1. What is zero order reaction ?

Ans. The reaction in which rate of reaction is independent of concentration of the reactant is called as
zero order reaction.
e.g. H2 +Cl 2HC1

  1. What is the order of the reaction given below? 2N2O5→ 2N2O4 +0

Ans. It is a Ist order reaction.

  1. Give an example of 1st order reaction

Ans. PCI, PCI, + ClL
Experimentally found, Rate K [PCi]
So order of reaction=1
Rate of reaction is directly proportional to 1st power
of the concentration of reactant.

  1. Write the integrated rate equation for 1st order reaction.
    Ans. 2.3031og
    Where K = rate constant of the reaction.
    a initial amount of reactant.
    x amount decomposed in time ‘t
  2. If the rate constant of a reaction is same as the rate of reaction at any concentration of reactant, what is the order of reaction ?

Ans. Zero order reaction

  1. Give an example of fractional order reaction
    Ans. CH,CHO CH, +CO Rate K[CH,CHO order of the above reaction = 1.5
  2. For a reaction half life period is independent of initial concentration of reactant. What is the order of reaction 2

Ans. First order reaction

  1. Rate constant of a reaction depends upon.

Ans. temperature

  1. The reaction A + 2B 2C obeys the rate equation: Rate = KAB What is the order of the reaction?

Ans. Order =+3/2 =2

  1. What is photochemical reaction ?

Ans. The reaction whose rate is influenced by light radiation is called as photochemical reaction.
e.g. photosynthesis, decomposition of H,O,.

  1. For a zero order of reaction the concentration.

Ans. Varies directly with

  1. How does rate of zero order reaction vary with progress of time ?

Ans. Rate of a zero order reaction remaians unchanged with progress of time. t, C

  1. For ‘n’ th order reaction,

Ans. ca-n/2

  1. For a zero order reaction, the molecularity is zero. Yes or no

Ans. No, moleculararity of a reaction can never be Zero.
E2

  1. In the equation K – Ae RT, what is A

Ans. A is a constant called as collision number or frequency factor and its unit is sec

  1. How does the value of K’ vary with activation energy ?

Ans. As the value of activation energy increases the rate constant (K) value decreases. (As given in Arrhenius equation)

  1. Can all molecular collisions yield the product ?

Ans. No, only the effective collisions yield the
product.

  1. What is the condition when all collisions between the molecules can be effective collision ?

Ans. When activation energy of the reactant is zero,
then K= A. Where K rate constant A = collision number.
Under such conditions all collisions can be effective
collision to form the product, But this concept 1s
theoritical.

  1. What is the unit of zero order reaction

Ans. Mol lit sec .

  1. Write two factors which influence rate constant of a reaction ?

Ans. Temperature and catalyst.

  1. The ratio between the rate constants at two different temperature differing by 10°C is called

Ans. Temperature co-efficient

  1. For a 1st order reaction when rate of reaction is platted conc. of reactant a straight line is obtained whose slope is 2.5. What is its rate constant.

Ans. Rate constant = slope = 2.5 Sec

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