The correct answer is "Amine peaks show up in the range, whereas alcohol peaks show up in the range. Amine peaks are sharper, "pointier," than alcohol peaks, which are usually strong and broad." The other answers contradict this statement.

Infrared Spectroscopy is used to determine the functional groups present in a molecule. It makes use of the IR region of the electromagnetic spectrum. When an analyte is exposed to IR radiation, different functional groups absorb radiation at their characteristic wavelengths causing vibrational and rotational excitation to bonds within the molecule. The frequencies absorbed correspond to the amount of energy required to increase the molecular vibration of the functional groups in a molecule and can be plotted on a graph for analysis.

This peak exists as a result of the presence of an aldehyde.

Any time that an IR spectrum shows a strong, sharp peak in between , we know that we have a carbonyl functional group present. The aldehyde is the only carbonyl out of the listed answer choices.

Frequency is directly proportional to wavenumber, as both quantities are inversely proportional to wavelength. Thus one can order the resonances in order of increasing wavenumber:

has the lowest wavenumber

sp3

sp2

To calculate the Rf you must determine the length the solvent traveled starting at the position of the compound. Then determine how far the compound traveled.

To determine the distances you must analyze the given information. The compound distance traveled is given (15 mm). The solvent distance is started from where the compound was spotted to where the solvent was stopped (the dashed line). If the TLC plate is 60 mm, then subtract 5 mm since the compound was spotted 5 mm up the plate from the bottom. Then subtract another 5mm because the solvent was stopped 5 mm from the top:

The correct answer is carboxylic acid.

We know that the strong, sharp peak at must correspond to a carbonyl group. This information does not help us much, however, as all of our answer choices contain at least one carbonyl.

The other defined peak at is the key to solving this problem. Strong, broad peaks are characteristic of bonds. However, this peak was absorbed at too low of a frequency to correspond to an alcohol group. Thus, our peaks must correspond to carboxylic acid, as it is the only answer choice that is a carbonyl group but that also contains an bond.

It is most useful for determining the type of nuclei (most commonly studied nuclei are and ) present and their relative locations within a molecule. H-NMR is most commonly used because it is practically present in all organic compounds. This technique is useful for a complete determination of the structure of organic compounds.

The most polar compounds will stick to the TLC plate and not follow the solvent very much, if at all. The more non-polar compounds will tend to follow the solvent front and therefore have the highest Rf. Rf is the distance the compound travels divided by the distance the solvent travels. The most non-polar compound is iso-propylbenzene, IV, followed by acetophenone, I. Benzyl alcohol, II, would be followed by benzoic acid, III, which would not move up the plate much at all. Alcohols are polar compounds, as are carboxylic acids, which are the most polar of the four listed.

The correct answer is "two of these" -- namely, "It can be used in tandem with gas chromatography to determine the molecular size of the compound" and "It helps determine the mass of a molecule, and gives clues about its structures by showing the most favored molecular fragments."

Gas chromatography (GC) helps show the molecular weight of compounds in a sample, by illuminating their various evaporation rates (which correspond to molecular size). Mass spec helps show the mass of the molecule - to an exact amu - by ionizing it to a positive cation and putting it into an electrical field and detector which can record its charge and mass. Mass spec also illuminates structural components of the molecule, because it shows the masses of the most fragments, and the likeliest fragments occur according to the structural possibility of the original molecule to fragment in a particular way.

Incorrect answers:

"It helps determine the mass of a molecule, though it cannot provide any other structural information." -- It shows structural information by showing the massses of the fragments.

"It helps show the approximate mass of a molecule, though it is unlikely to at all show the actual mass of the original unfragmented molecule." -- mass spectrometry shows the actual mass of the unfragmented molecule as the "parent peak" -- the peak with the largest m/z value (even if lower abundance than the base peak, which usually corresponds to the most likely fragmentation pattern).

A SN1 reaction proceeds with loss of stereochemistry. A pure chiral compound rotates plane polarized light. This is measured as an optical rotation in degrees. Two enantiomers have equal and opposite optical rotations. If the starting material has an optical rotation of , then it's enantiomer has the same rotation, but negative . In this case the reaction will become racemic (equal amounts of both isomers) and have an optical rotation of .