Reference no: EM132422676

Questions -

Q1. A semiconductor exhibits a band gap of 2.50 eV. Which wavelength of radiation is required to excite electrons to the conduction band?

Q2. What is the general elution problem? Describe why an elution gradient in HPLC can address this issue?

Q3. Describe between normal phase and reverse phase HPLC? Which method would you choose for the separation of alcohols?

Q4. Why does the pH affect separations of amino acids by electrophoresis? The electrode reactions in electrophoresis affect pH. How is this influence on separation addressed in an electrophoresis experiment?

Q5. In potentiometric experiment, Ag/Agcl electrode is immersed in a solution containing an unknown amount of Cl^- ions. A potential of 0.205 V is measured between this working electrode and a Ag/Agcl reference electrode in solution of 1M Cl^- concentration. (T=298.15^oC)

Q6. Based on a lattice parameter a=4.0 Å and x-ray wavelength 1.2 Å, calculate the diffraction angle θ for the (1 0 0) plane.

Q7. Describe the purpose and physical principle of a lens within an electron microscope.

Q8. You need to determine the oxidation state of iron in an unknown solid iron compound.

Q9. For diprotic acid H₂A with pK_a1 = 2.4, pK_a2 = 7.6 calculate the approximate concentrations of each spices (H₂A, HA^-, A^2-) at a pH = 4.0. If their total concentration is 1.0 M.