Physical Chemistry Lab II

A list of experiments under different headings is given below. Students are required to perform at least 8-10 experiments.

Chemical Kinetics

1. To determine the effect of (a) change of temperature (b) change of concentration of reactants and (c) catalysts on the velocity constant of hydrolysis of an ester.
2. To study the kinetics of the reaction between K₂S₂O₈ (potassium persulphate) and KI (potassium iodide) and to determine the rate constant and the energy of activation of the reaction.
3. To determine of primary salt effect in the kinetics of ionic reaction and to test the Bronsted relationship (Iodide ion is oxidized by persulphate ion).
4. To study the kinetics of saponification of ethyl acetate by sodium hydroxide and to determine the rate constant.
5. To determine the rate constant, energy of activation and entropy of activation in the oxidation of benzyl alcohol (C₆H₅CH₂OH) by potassium permanganate in acidic medium.
6. To determine the formation constant for the (Ce⁺⁴-H₃PO₂) intermediate complex and its decomposition rate constant at the room temperature.
7. To determine the rate constant for the bleaching of malachite green in basic medium at room temperature spectrophotometrically.
8. To determine the rate constant, order of reaction and energy of activation for saponification of ethyl acetate using NaOH conductometrically.

Electrochemistry

1. To estimate the concentration of H₂SO₄, CH₃COOH and CuSO₄ by conductometric titration using NaOH solution.
2. To determine equivalent conductance of the strong electrolytes (KCl, HNO₃, HCl etc.) at several concentrations and to verify the Onsagar’s equation and find the values of a and b in the equation.
3. To determine the equivalent conductance of acetic acid at infinite dilution and to calculate its degree of dissociation at different dilutions as well as dissociation constant at the room temperature.

Potentiometry

1. To determine the concentration of ferrous ion in the given solution by titrating against N/10 Cr₂O₇^-- or Ce⁺⁴ ion solution and also determine the equivalence point by plotting E vs. V, ∆E vs. ∆V and ∆²E/∆V² vs. ∆V.

Polarography (demonstration)

1. To determine the half wave potentials of Cd⁺² and Zn⁺² ions in 0.1 M KCl solution and to show that half wave potential is independent of the concentration.

Adsorption

1. To study the adsorption of acetic acid or oxalic acid from aqueous solution by activated charcoal or animal charcoal and to examine the validity of Freundlich and Langmuir adsorption isotherms.
2. To compare cleansing power of samples of two detergents.
3. To study the variation of surface tension of solution of n-propyl alcohol with concentration and to determine the limiting cross section area of alcohol molecule.
4. To determine the radius of molecule by viscosity measurements (e.g. Glycerol)

Scheme of Examination

The duration of the examination will be 6 hrs.

The following exercises will be set in the examination

Physical Chemistry Experiment                           55 marks

Viva                                                                  15 marks

      Total                                                                      70 marks

1. Physical Chemistry Experiment

The exercise carries 55 marks. The candidates shall be given one exercise out of exercises prescribed in the syllabus. The exercises in physical chemistry can be modified by the examiner and the same will be explained to the candidates. However, such modifications will not involve any departure from the basic principles over which experiments are prescribed in the syllabus.

Candidates shall be given one exercise out of the exercises prescribed in the syllabus.

The distribution of marks will be as follows

1. Theory and procedure                                       10 marks
2. Correct observation                                           15 marks
3. Use of correct formula                                       8   marks
4. Calculation                                                        15 marks
5. Results                                                              7   marks

No marks for calculation will be awarded to a candidate for not calculating the result.

The permissible error will depend on the nature of the experiment. Generally, + 10% error may be taken as permissible error for experiments involving potentiometric and conductometric measurements. The constancy in values of rate constants may be taken into consideration while awarding marks in experiments on chemical kinetics. One mark shall be deducted for each + 2% error over permissible limit.

2. Viva

Oral questions shall generally be asked about the work assigned to the candidate. The purpose is to find out to what extent the candidate understood the basic principles of chemistry.