Chemical Kinetics

Question 1

Unit of rate of reaction.

Answer 1

Mol per litre per second

Question 2

What do you know about the rate constant k ( specific reaction rate ) ?

Answer 2

Rate constant l depends on temperature and is independent of the concentration of the reactants. At fixed temperature k is constant.

Question 3

What is molecularly of a reaction ?

Answer 3

Molecularity is a whole number (not zero) and a never a fraction. It’s value does not exceed 3 and has no meaning for a complex reaction.

Question 4

Define order of a reaction ?

Answer 4

The order of a reaction is determined through experiments. Order of a reaction can be a fraction or an integer. In a multi step reaction order is qual to the order of slowest step called rds.

Question 5

How is order of an elementary reaction found out ?

Answer 5

In an elementary reaction the order is equal to the stochiometric coefficients of the reactants.

Question 6

What is the unit of a zero order reaction ?

Answer 6

Mole per litre per second.

Question 7

What is the unit of a first order reaction. ?

Answer 7

Per second.

Question 8

What is the unit of a second order reaction ?

Answer 8

Litre per mole per second.

Question 9

What is the half life of a zero order reaction?

Answer 9

[R]0/2k

Question 10

What is the half life of a first order reaction?

Answer 10

0.693/k

Question 11

What is the half life of a second Order reaction?

Answer 11

1/k[R]0

Question 12

What is the straight line plot for a zero order reaction ?

Answer 12

[R]0 vs t

Question 13

What is the straight line plot for a first order reaction?

Answer 13

ln[R] vs t

Question 14

What is the straight line plot for a second order reaction ?

Answer 14

1/[R] vs t

Question 15

For a first order reaction , what is t(75%) or t(3/4)?

Answer 15

2 t1/2

Question 16

For a first order reaction , what is t(87.5%)?

Answer 16

3 t1/2

Question 17

For a first order reaction, what is t(99.99%)?

Answer 17

10 t1/2

Question 18

What happens to rate constant k when temperature for a general chemical reaction is increased by 10 degree celcius ?

Answer 18

Rate constant k is doubled

Question 19

What is Arrhenius Equation?

Answer 19

K= Ae^ -Ea/RT

Ea- Activation energy.

Question 20

What are the factors affecting reaction rates ?

Answer 20

Concentration of reactants and reaction temperature. Besides these, presence of catalyst and surface area for a solid reactant.

Question 21

Half life of a zero order reaction t1/2=?

Answer 21

t1/2= [A]o/2k

Question 22

Simplified Arrhenius Eq log k2/k1=?

Answer 22

log k2/k1 = -Ea/2.303R (1/T2 - 1/T1)

Question 23

For first order reaction , rate constant k=?

Answer 23

k= 2.303/t log a/a-x