arkachowdhury575

1) Which approach seems to be best for obtaining computed vibrational wavenumbers, given the time which it took to get them? Are the 6-31G** and DFT results worth the time expense? (Molecular Mechanics calculations, Hartree-Fock (HF) 3-21G* ab-initio calculations , HF/6-31G** ab-initio and Density Functional Theory (DFT) calculations )

3) Given that these calculations include all of the atoms and electrons in a system, what would you expect to happen for larger molecules? What would happen to the time require for ethanoic acid, propanoic acid, butanoic acid, etc. Which methods would you use for the larger molecules?

4) Based on your answer from 3, could you envision using these techniques for the prediction of biomolecules, with molecular masses on the order of 10,000+ amu? Why or why not?

5) The basis sets model the electrons in the compound. What might you think happens in terms of computational “expense” (time), for calculations performed on a family of related compounds: CH4, SiH4, GeH4, SnH4, and PbH4?

Which of the following substances would be expected to have the lowest heat of fusion? 1. SiH4 2. GeH4 3. methane 4. SnH4 5. PbH4

Which of the following substances would be expected to have the lowest heat of fusion? 1. propane 2. methane 3. pentane 4. butane 5. ethane

Which molecule has the most negative heat of combustion in kcal/mole?

a. methane

b. ethane

c. propane

d. butane

Which of the following compounds possesses the most deshielded proton?
A. Ethane B. Methane C. Ethene D. Propane

in which of the following compounds carbon-hydrogen bond shows the highest stretching vibration frequency in its IR spectrum? a) ethane b) ethene c) ethyne d)methane

What are the H-C-H bond angles in Ethane, Ethene, and Ethyne?