Lab practical study guide

Question 1

what if melting point capillary has too much sample

Answer 1

broad melting point range

Question 2

where is the organic layer in sep funnel

Answer 2

top

Question 3

where is halogenated organic in sep funnel

Answer 3

bottom

Question 4

where is non-halogenated organic in sep funnel

Answer 4

top

Question 5

where is polar material in sep funnel

Answer 5

bottom

Question 6

where is non-polar material in sep funnel

Answer 6

top

Question 7

what layer is an acid w organic solvent

Answer 7

organic layer

Question 8

what layer is base w organic solvent

Answer 8

aqueous layer

Question 9

what causes low melting point

Answer 9

impurities, wet sample, amount of sample in tube

Question 10

what to do if crystals don’t form in recrystallization

Answer 10

-scratch flask w stir rod
-concentrate solution by boiling off solvent
-use crystals as seeds

Question 11

what to do if too much drying agent used

Answer 11

-decant or gravity filter
-rinse drying agent w fresh solvent and combine risings with fresh solution

Question 12

what happens if too much drying agent is used

Answer 12

will reduce percent yield

Question 13

Best way to measure 1mL of liquid

Answer 13

pipette w/ bulb

Question 14

best way to measure 10 mL of liquid

Answer 14

graduated cylinder

Question 15

best way to measure 0.01g

Answer 15

weigh paper and analytical balance

Question 16

how would you purify 40mg of solid that has a byproduct present

Answer 16

column chromatography

Question 17

purify 4g of solid that is 95% pure

Answer 17

recrystallization

Question 18

purify 40mL of liquid that is 80% pure

Answer 18

simple distillation

Question 19

seperate two liquids with 5 degree difference in BP if i had 100mg

Answer 19

fractional distillation

Question 20

separate two liquids with 5 degree difference if had 100 mL

Answer 20

vacuum distillation

Question 21

***how would you isolate a temp sensitive extract present as 5% component from natural matrix

Answer 21

extraction, TLC

Question 22

**best apparatus for reducing from C=O to C-OH

Answer 22

heat under reflux

Question 23

best apparatus for an unknown solid

Answer 23

melting point analysis

Question 24

best for isomers of a compound with same functional groups

Answer 24

NMR

Question 25

**best for small reaction mixture to get Keq

Answer 25

UV

Question 26

where does IR data come from

Answer 26

oscillation of molecular dipoles

Question 27

what does IR data tell us

Answer 27

functional groups

Question 28

where does NMR data come from

Answer 28

uses magnetic properties

Question 29

what does NMR tell us

Answer 29

spin states, shielding, and peaks

Question 30

where does GC data come from

Answer 30

separation within column

Question 31

what does GC data tell us

Answer 31

conformation and structural properties

Question 32

where does GC/MS data come from

Answer 32

mass: charge ratio

Question 33

what does GC/MS data tell us

Answer 33

detect tiny sample amounts

Question 34

where does UV data come from

Answer 34

e- moving from high to low orbital

Question 35

what does UV data tell us

Answer 35

electronic transitions and structure

Question 36

what is refluxing

Answer 36

boiling of a solution while continually condensing the vapor by cooling and returning ot reaction flask

Question 37

what is extraction used for

Answer 37

separate an organic product from a reaction mixture

Question 38

what is distillation used for

Answer 38

purify liquids

Question 39

stationary phase

Answer 39

silica gel

Question 40

mobile phase

Answer 40

solvent or mixture of solvents

Question 41

simple distillation

Answer 41

less surface area, less accurate

Question 42

fractional distillation

Answer 42

-more surface area, more accurate
-condense and evaporate repeatedly