Sample Questions for Midterms and Semi Final Exams
Sample questions for midterms and semi final exams
In your answer explain the meaning of all parameters you used. E.g. C = capacitance, R = universal gas constant..
Electric properties of material I.
Characterize a parallel plate capacitor by its electrical parameters. Write equations if that is needed.
Give two definitions for electric field strength.
How do you calculate εr.
Molecular structure – dipole moment, example: chloro benzene derivatives. Compare the magnitude of different chloro benzene derivatives
Debye equation is given as , how do you determineα and µ?
Electric properties of material II
Give an explanation of differnt types of polarizations.
Distinguish between Po and Pd. Use the frequency dependence of polarization.
A light beam travels from medium n1 to medium n2, and n1n2. Make a figure depicting the situation.
All about: refractive index!
At what conditions does µ become zero, give the meaning of letters in the equation!
Using this Figure’s notations
give potential energy distance dependence of this system.
The Boltzmann Distribution
You have N = n1 + n2 molecules altogether, n1 at the zeroth level, and n2 at the first level.The first level is more energetic thean the zeroth one. Give the n2/ n1 ratio applied the Boltzmannstatistics.
Selection rules
Born-Oppenheimer approximation: the type of additivity it expresses.
All about transition integral!
Spectral intensities and transition integral.
Calculate the energy of 285 nm photon (c = 3 108 m/s, h = 6,63 10-34 Js). Using the Planck equation.
Reproduce the energy level diagram of different electronic transitions.
Vibration and rotation selection rule.
Beer Lambert’s Law
Energy flux of photons – the formula.
The light intensity reduction asross a liquid layer of thickness b. Characteristic parameters and figure.
Definitions: transmittance, percentage transmittance, absorbance and their transformation formulas.
Beer-Lambert’s law, derive the equation.
Concentration series and linear concentration dependence, make drawings to demonstrate them.
A 2 mm path-length cell is filled 0.01 M benzene. The wavelength is set to maximum wavelength of benzene, 256 nm. At this wavelength the transmitted intensity was 48% of incident intensity. Suppose the solvent absorbance can be neglected. What is the molar absorbance and absorbance of benzene at this wavelength?
pH dependence of the spectrum of a weak acid indicator. Show the absorbance wavelength function of indicator dissolved in three different pH solution.
Raman spectroscopy
All about Rayleigh scattering, Raman effect!
Stokes scatter, anti Stokes scatter, formulas for frequency shift.
Read from the graph the main characteristic features, e.g. the origin and position of peaks…
Beer-Lambert’s law and its usage,
Set out the chemical limitations of Beer Lambert’s law, and write in details 3 of them.
Spectral band shift:cromophore, red shift, conjugative effect, phase and solvent effect, explain the concepts.
At what wavelength of a spectral band would you collect absorbance data for a concentration calibrating curve? Tell the reason why.
Luminescence spectroscopy
Singlet and triplet electronic states (make a drawing to demonstrate).
Compare in terms of wavelength and energy of absorbed and emitted fotons in the fluorescence process!
Singlet and triplet electronic states and their role in fluorescence and phosphorescence phenomena.
Detail the energy releasing process in phosphorescence.
Photo electric spectroscopy
Describe the change in energy during the photo-electric process. Which term of equation is measured?
Review the working principle of photoelectron energy analyzer!
Make a drawing for the XPS spectrum of solid NaN3 excited by Al Kα radiation, to explain the ionic structure of nitrogen atoms.
Vibrational spectroscopy
Give the number of normal vibrations for linear and nonlinear molecules. Explain your answer!
Reduced mass (definition) and its role in vibration movement?
The harmonic oscillator model, its description: quantum jump, vibrational energy equation, energy level distances.
The anharmonic oscillator model, its descrition: quantum jump, vibrational energy equation, level distances in energy.
Calculate the number of normal vibrations for ethylamine, propan-1-ol, CS2
Rotational energy
Give definitions: torque, moment of inertia, angular momentum, rotational energy.
Selection rule for rotational motion, allowed rotational quantum jump (ΔJ).
Explain the meaning of parameters and variables, , which parameter specifies the bond angles and bond distances?
Rotational constant is given as , how does the value of constant change?
NMR spectroscopy
(This lecture is the theme of semi-final exam only)
Which isotopes have net spin angular momentum for the following elements: 1H, 19F 12C, 14N, 31P?
The chemical shift and shielding.
δ-scale, the chemical shift.
All about the shielding process with examples.
What is this:
Explain the energy difference between nuclear spin states, which is absorbed by the system.
Local field effect, para- and diamagnetic contribution
Compare the effect of natural isotope abundances of hydrogen and carbon, especially for measuring conditions.
The NMR instrument, building up and measuring principle.
Spin - spin coupling, explained by using example ethanol.