ochem lab 2

Question 1

t or f: liquid-liquid extraction allows us to purify liquids and solids

Answer 1

T

Question 2

what does liquid-liquid extraction use

Answer 2

solubility differential of substance in different solvents

Question 3

requirements of solvents

Answer 3

must be immiscible, and new solvent must dissolve solute more

Question 4

k= c2/c1

Answer 4

c2 is concentration in second extracting solvent

Question 5

what is the extracting solvent

Answer 5

the second one that is added

Question 6

it is more effective to extract more times with smaller amounts of extracting solvent than fewer times with larger amounts of extracting solvent. T or F

Answer 6

T

Question 7

performing ________ extractions gets most sample out of original solvent

Answer 7

2-3

Question 8

more concentrated the solution, the more ___ the extraction

Answer 8

efficient

Question 9

is methylene chloride an extracting solvent?

Answer 9

yes, compared to water it is much less polar

Question 10

is methylene chloride lighter or heavier than water?

Answer 10

heavier

Question 11

how can emulsions be broken up

Answer 11

change concentration by adding more of original solvent, add neutral salt to change density of aqueous layer, or centrifuge

Question 12

washing the organic layer

Answer 12

shake with distilled water

Question 13

drying the organic layer

Answer 13

remove trace water and treat with a drying agent like anhydrous sodium sulfate (add w/ spatula or filter through a column containing drying agent)

Question 14

organic layer

Answer 14

usually contains organic compounds like unreacted alcohol

Question 15

aqueous layer

Answer 15

contains inorganic salts and sulfuric acid

Question 16

purpose of washing

Answer 16

dissolves inorganic compounds like salts

Question 17

how to get rid of sulfuric acid

Answer 17

n-butyl bromide layer (organic) is washed with aqueous solution of sodium bicarbonate and inorganic products go to the water layer

Question 18

how much anhydrous sodium sulfate should be affed

Answer 18

only enough to cover bottom of container

Question 19

organic acids

Answer 19

carboxylic, acetic, benzoic, but also phenol and ethanol and alcohols

Question 20

common bases

Answer 20

amines like diethylamine and aniline (high pka)

Question 21

small organic bases are ____ in water

Answer 21

soluble

Question 22

is aniline soluble in h2o

Answer 22

no

Question 23

diethyl amine soluble in h2o

Answer 23

yes

Question 24

benzoic and phenol soluble no

Answer 24

no

Question 25

acetic acid and ethanol soluble in water

Answer 25

no

Question 26

how to dissolve carboxylic acid

Answer 26

sodium bicarbonate, nahco3 since carboxylic stronger than phenol, will not react with phenol. others are not responsive to bases

Question 27

dissolve phenol

Answer 27

add aqueous naOH since phenol is weak acid needs strong base.

Question 28

dissolve amine

Answer 28

add aqueous hcl- converts to hydrochloride salt a stable solid

Question 29

dissolve ketone in water

Answer 29

not possible; remains in ether

Question 30

recover pure phenol

Answer 30

add acid to aqueous layer to reprotonate phenol after separating layers

Question 31

signs a solution is dry

Answer 31

no puddles of water, solution is clear and homogeneous

Question 32

aspirin soluble in

Answer 32

dichloromethane and basic water

Question 33

acetominophen

Answer 33

soluble in ethanol but not dichloromethane

Question 34

caffeine

Answer 34

dichloromethane soluble

Question 35

aspirin is aka

Answer 35

acetalsalysilic acid

Question 36

aspirin goes with

Answer 36

hcl and k2hpo4

Question 37

acetaminophen goes with

Answer 37

koh and hcl

Question 38

extracting substance in aspirin

Answer 38

k2hpo4

Question 39

extrator acetominophen

Answer 39

koh and after hcl, ethyl acetate