M.Sc. (Semester IV) (CBCS) Examination Nov/Dec-2018
Physical Chemistry
CHEMICAL KINETICS
Time: 2½ Hours
Max. Marks: 70
Instructions: Attempt in all five questions. Section I is compulsory Attempt any two questions from section II and section III. Answer to all questions (Section II and III) should be written in same answer book. All questions carry equal mark. Figures to right indicate full marks. Use of log table and calculator is allowed.
Section I
Q.1
Answer the following:
14
Give the expression for Arrhenius equation.
According to the collision theory, the reaction rate is a function of the collision number. The above statement is true or false.
If Ea is the product of R and then Arrhenius pre exponential factor A is
ke2
ke
k/e
e/k
According to collision theory what is orientation factor?
What do you mean by pseudo-unimolecular reaction?
In a chemical reaction, if short lived species formed, the rate of formation is equal to the rate of decomposition. [True False]
Give an example of parallel reaction.
What is steady state approximation?
What do you meant by the term chain length?
Write the chain termination step in the reaction between H2 and I2.
Can the presence of catalyst influence the equilibrium conditions once they are attained?
The nature of potential energy versus reaction co-ordinate plot is
Activation energy of a catalysed reaction is generally less than the uncatalyzed reaction. True or False
The Lineweaver-Burk plot is
Section II
Q.2
Discuss in detail the Lindemann's mechanism for unimolecular reaction.
07
Explain how the activation energy, enthalpy of activation and entropy of activation of a reaction are calculated on the basis of activated complex theory.
07
Q.3
What are complex reactions? Mention various types of complex reactions. How they differ from the simple elementary reactions?
07
Obtain an expression for the Michaelis-Menten equation. Explain the features of the Michaelis-Menten plot.
07
Q.4
Discuss the kinetics of branching chain reactions and explosion limits.
07
Illustrate the characteristics of oscillatory reaction with suitable example.
07
Page 2 of 2
SLR-VF-176
Section III
Q.5
Explain how pH and temperature affects the catalysed reactions.
05
Illustrate the Lineweaver-Burk plot.
05
What are acidity functions? Explain their significance.
04
Q.6
Discuss weakness of the collision theory of reaction rates.
05
What is the significance of partition function in activated complex theory?
05
For a consecutive reaction
A B C The values of k1 and k2 are 1.62x105 and 5.4x104 sec-1 respectively. Calculate the time required for the concentration of B to reach maximum.
04
Q.7
Write a note on any Three of the following.
14
Assumptions made in activated complex theory
Kinetics of parallel reactions
Rate determining step of a chemical reaction
Autocatalytic reactions