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Birla Institute of Technology & Science, Pilani, Rajasthan 333031

First Semester 2013-2014

Course Number: CHEM F111 Course Title: General Chemistry Marks: 8

Tutorial Problem Set 1 (based on Lecture No.s: 1-8 in the course hand out)

Instructions to the student: The following problems should be solved as home assignment within a week ofdisplay. Any one problem will be assigned as a closed book class test in the following tutorial hour.

Useful data: me = 9.11 x 10-31

kg, h = 6.626 x 10-34

Js , 1 eV = 1.602 x 10-19

J, = 1.055 x 10-34

Js

Q. 1 Draw the potential energy diagram showing various conformers of cyclohexane and draw the Newman

projection of the most stable conformer. [6+2]

Q. 2 (a) Draw the possible chair conformations of trans-1,2-dimethylcyclohexane and trans-1,3-

dimethylcyclohexane. In each case determine, which of the two conformers is more stable. [2+2+2]

(b) Draw the most stable conformer of 2-chloro-1-ethanol in Newman projection. [2]

Q. 3 (a) One of the two chair structures ofcis-1-chloro-3-methylcyclohexane is more stable than the other by

3.7 kcal/mol. Draw the two structures and indicate which of them is more stable and why. What is the energy

of a 1,3-diaxial interaction between a chloride and a methyl group? Given that the energy of 1,3-diaxiainteraction between a methyl-hydrogen (CH3-H) is 0.9 kcal/mol and that of and chloride-hydrogen (Cl-H) is

0.25 kcal/mol. [1+2+2]

(b) Compute the change in vibrational frequency of HI, when H is replaced by deuterium (D) (Assume HImolecule is vibrating with stationary I atom and H oscillating towards and away from I atom). [3]

Q. 4 Write absolute configuration at the chiral centre(s) for the following molecules: [2+2+2+2]

Q. 5 (a) Write the total number of asymmetric carbon atom(s) if any, in the following molecules:

[3]

(b)

Write Fischer formula for all of the stereooisomers of CH3CHClCHClCH2CH3. Label the pair of enantiomersand meso compounds if any. [4+0.5+0.5]

Q. 6 (a) Label the following molecules as chiral or achiral. [4]

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(b) Write the relationship between the following pairs as enantiomers, diastereomers and identical

compounds. [4]

Q. 7 (a) Determine the maximum wavelength in nm of light necessary to overcome the work function of 2.90

eV of lithium metal. [4]

(b) Calculate the energy of the first excited state of an electron moving in a ring of radius 1.0 nm. [4]

Q. 8 (a) For a particle in a one-dimensional box of length L, normalize the following wave function:

n = Nsin(nx/L). [4](b)Calculate the energy difference between first two energy levels of an electron confined in a one-

dimensional box of length 1.0 nm. [4]

Q. 9 (a) Compute the energy in joules emitted by an atom emitting a spectral line with frequency 1015

s-1

What is the energy of the light emitted by 1 mole of such atoms? Compare this with the kinetic energy of a

person walking (60 kg, 6 km/h) and with the energy of a 60 W light bulb burning for 1 hour. [4]

(b) What is the maximum precision with which momentum can be known if the position of an electron isdetermined within 1 x10

-13m? Will there be any problem in describing the momentum if it has value of

/0.0529 nm? [4]

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