4. Laboratory Techniques

Question 1

extraction

Answer 1

separation based on solubility
like dissolves like

Question 2

in an extraction, a weak acid will bind…

Answer 2

strong base

Question 3

in an extraction, a strong base will bind…

Answer 3

weak and strong acid

Question 4

in an extraction, a strong acid will bind…

Answer 4

weak and strong base

Question 5

in an extraction, a weak base will bind…

Answer 5

strong acid

Question 6

distillation

Answer 6

separation based on boiling points
slow boil
lower boiling point will vaporize and be captured in cool tube

Question 7

crystilization

Answer 7

separation based on purity
pure forms crystals more easily than impure

Question 8

chromatography

Answer 8

used to purify a compound from a mixture to determine the ratio of compounds in a mixture

pass mixture over a matrix that binds different compounds more or less strongly

Question 9

stationary phase

Answer 9

polar
made from matrix
solid surface

Question 10

mobile phase

Answer 10

mixture dissolved in solution
if more affinity for polar stationary phase, will elute more slowly

Question 11

column chromatography

Answer 11

matrix (stationary phase) is in column tube in form of glass beads
uses polarity

Question 12

paper chromatography

Answer 12

• sample is spotted on paper
• one end of paper is placed in non-polar solvent
• solvent moves up paper by capillary action
• more polar compounds stay at bottom
• non-polar compounds move up paper with solvent

Question 13

thin-layer chromatography

Answer 13

same as paper but coated glass is used instead

Question 14

gas-liquid chromatography

Answer 14

stationary phase is liquid
mixture is dissolved into gas
compounds equilibrate with liquid at different rates
amount of each molecule eluted can be determined

Question 15

in size-exclusion chromatography, _____ molecules elute first

Answer 15

large

Question 16

ion-exchange chromatography

Answer 16

uses cationic or anionic exchangers to separate molecules based on charge

Question 17

southern blotting identifies specific sequences of _____

Answer 17

DNA

Question 18

northern blotting identifies specific sequences of _____

Answer 18

RNA

Question 19

western blotting identifies _____

Answer 19

particular protein in mixture of proteins

Question 20

what type of atoms register on NMR?

Answer 20

those with odd atomic mass or atomic number

Question 21

chemical shift of aldehyde proton

Answer 21

9.5

Question 22

chemical shift of carboxylic acid proton

Answer 22

10-12

Question 23

chemical shift of benzene proton

Answer 23

8

Question 24

chemical shift of alcohol proton

Answer 24

1-5

Question 25

chemical shift of methyl proton

Answer 25

1

Question 26

atoms with greater mass resonate at _____ frequencies

Answer 26

lower

Question 27

stiffer bonds (double, tripe) resonate at ______ frequencies

Answer 27

higher

Question 28

IR spectra of C O double bond

Answer 28

1700

Question 29

IR spectra of O-H

Answer 29

3200-3600

Question 30

IR spectra of C C triple bondleo

Answer 30

2200

Question 31

IR spectra of C-O

Answer 31

1100

Question 32

NMR deals with...

Answer 32

magnetic spin of hydrogen or carbon nuclei

Question 33

IR spectroscopy deals with...

Answer 33

the way IR light causes bonds with dipoles to vibrate and rotate

Question 34

UV spectroscopy deals with...

Answer 34

the way UV light affects electrons in conjugated systems

Question 35

when does a compound move into the visible region?

Answer 35

when it has 8 or more double bonds