FREE MCAT AND STUDY GAMES ABOUT MCAT O CHEM

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FREE MCAT AND STUDY GAMES ABOUT MCAT O CHEM

EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -24 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation

Question 1: important peaks on mass-spec

Answer:

base peak-tallest peak, most abundant ion, assigned relative abundance of 100. Molecular ion or parent peak (M+) peak furthest to the right, usually equivalent to molecular weight of original molecule

Question 2: IR amines

Answer:

sharper peaks at 3,300 and 3,400cm-1 for primary amines, secondary amines have one peak

Question 3: NMR spec based on hybridization

Answer:

H bonded to sp3 hybridized carbon shift between 0 and

• if bonded to an sp2 hybridized carbon shift between 5-10. divide spectrum in half, sp3 right, sp2 left

Question 4: IR hydroxides

Answer:

broad peak at 3,300cm-1

Question 5: what does the area under the signal represent

Answer:

the total area under the signal corresponds to the number of nuclei represented by that signal

Question 6: what does H-NMR measure

Answer:

how deshielded (how much electron density has been pulled away) protons are on a molecule.gamma=0-12 ppm. the more deshielded the proton is, the further down-field it will be.

Question 7: Alkane C-H peak

Answer:

sharp peak, below 3000

Question 8: H-NMR caroxylic acid

Answer:

10.5 to 12 ppp (highly deshielded)

Question 9: C-NMR

Answer:

similar to H-NMR but gamma=0-210ppm

Question 10: compounds that will show absorption in the 1750 region

Answer:

(carbonyls) ketones, aldehydes, carboxylic acids, any caboxylic acid derivative(acid anhydrides, acid halides, amides, esters)

Question 11: Mass spectroscopy

Answer:

used to find the mass of the compound and the masses of fragments of the compound

Question 12: IR carbonyls

Answer:

sharp peak at 1,700cm-1

Question 13: mass spectroscopy results in the separation of fragments according to

Answer:

mass-to-charge ratio

Question 14: H-NMR hydrogen aromatic ring

Answer:

6.5 to 8.5 ppm

Question 15: H-NMR

Answer:

useful to find the structure of a compound and can also reveal functional groups

Question 16: H-NMR coupling

Answer:

protons three bonds apart experience coupling. If there is one proton three bonds away, its a doublet; if there are two, its a triplet; three, its a quartet

Question 17: Amine N-H peak

Answer:

sharp peak, above 3000

Question 18: how to tell how much deshielding

Answer:

concept of electronegativity, the more electron density that is pulled away from the proton, the more deshielded in will be.

Question 19: what compounds are always conjugated

Answer:

aromatic molecule

Question 20: acid, alcohol O-H peak

Answer:

broad peak, above 3000

Question 21: symmetric bonds and IR

Answer:

do not show up because they involve no net change in dipole moment

Question 22: What is infrared spectroscopy used for

Answer:

find functional groups

Question 23: what is UV spectroscopy useful for

Answer:

conjugated compounds

Question 24: H-NMR aldehyde

Answer:

• to 10 ppm (highly deshielded)