Question

1. Gas chromatography is commonly used to _____________?

a) To check the purify of a volatile liquid sample, such as those obtained from a fractional distillation

b) To check the identity of an unknown substance by comparing its GC with the GC of a known

c) To analyze the components of a mixture for the presence or absence of a substance

2. All of the answers are applicable How many type of nonequivalent protons are in the following molecule? CH₃CH₂OCH₂CH₃

a) 1

b) 2

c) 3

d) 4

3. Which of the following is a factor that affects the ¹³C chemical shifts?

a) The electronegativity of the group attached to carbon

b) The atomic weight of the group attached to carbon

c) The hybridization of the hydrogen atoms

d) The number of hydrogen atom on an adjacent carbon atom

4. While 1H is the most abundant isotope of hydrogen, only ________% of the atom in carbon atoms in a sample are 13c

a) 1.1

b) 33

c) 50

d) 75

5. Where would you expect the peak for the benzyl cation (C₆H₅CH₂+) to appear in mass spec?

a) m/z 77

b) m/z 108

c) m/z 91

d) m/z 17

6. Predict the splitting pattern for each kind of hydrogen in the following molecule (make splitting assignment starting with the group labeled as A followed by group B and then group C) (CH₃)₂CHCOOCH₃^-

A B C

a) A doublet; B multiplet; C, singlet

b) A doublet; B quartet; C singlet

c) A singlet; b multiplet; C doublet

d) A doublet; B doublet; C singlet

7. The role of drying agent is to ____ after the extraction process is complete?

a) Increase the solubility of the solute in the organic solvent

b) Remove trace amounts of water from the organic solvent

c) Remove huge amounts of water from the organic solvent

d) Increase the polarity of the aqueous layer

8. The carbon of ____ will appear the most downfield in the 13C NMR spectrum?

a) The carbonyl group

b) An aromatic ring

c) An alkene

d) An alkane

Answer 1