uworld orgo

Question 1

the compound 4-nitrophenol contains all of the following in its infrared spectrum except

Answer 1

N-H stretch

Question 2

IR spectrum of a compound indicates

Answer 2

the types of bonds and functional groups present in a compound

Question 3

different functional groups absorb

Answer 3

IR radiation at diff frequencies

Question 4

signal from each group appears in a

Answer 4

particular region of the IR spectrum

Question 5

individual molecules may have distinct absorption spectra in the fingerprint region (700-1500 cm-1)…

Answer 5

each func group on the molecule will still absorb in its characteristic IR region

Question 6

4-nitrophenol contains

Answer 6

hydroxyl group (-OH)

aromatic ring

nitro groups (-NO2)

no N-H bonds –> no N-H stretch

Question 7

functional group bands appear in the

Answer 7

same region of the IR spectrum regardless of molecule’s overall structure

Question 8

distillation is a

Answer 8

purification technique that separates molecules based on boiling point

Question 9

a liquid mixture is heated to a temp that overcomes the

Answer 9

intermolecular forces keeping the compound in the liquid phase

vapors condense in the collection flask as a liquid

Question 10

molecule that dissipates in strong IM forces will have a higher or lower boiling pt?

Answer 10

a higher boiling point

Question 11

hydrogen bonding can be

Answer 11

intermolecular

intramolecular

Question 12

constitutional isomers can have different

Answer 12

boiling points due to difference in connectivity and that they experience different IM forces

Question 13

parasubstituent

Answer 13

1,4 relationship

Question 14

ortho substituent

Answer 14

1,2 relationship

Question 15

hydroxyl and nitro groups on 4-nitrophenol are…

Answer 15

para

Question 16

because of para hydroxyl and nitro groups on 4-nitrophenol, they are able to

Answer 16

H bond intermoleculary not intramolecularly

Question 17

intermolecular bonds hold molecules of 4-nitrophenol together, thereby..

Answer 17

increasing the boiling pt and causing i.t. to stay in the flask while the 2-nitrophenol distills

Question 18

superheating occurs when

Answer 18

a liquid is heated above its boiling pt but does NOT boil

Question 19

what can cause superheating?

Answer 19

surface tension - it inhibits formation of bubbles

Question 20

when bubbles attempt to form during superheating…

Answer 20

surface tension causes a local increase in vapor pressure

vapor pressure > ambient pressure

liquid heats beyond boiling pt

Question 21

bumping is

Answer 21

the formation of large bubbles at the surface that erupt and eject the hot liquid from the flask

Question 22

consequence of bumping

Answer 22

difficult to overcomes without damage to the flask

Question 23

boiling chips are made of

Answer 23

nonreactive porous materials + provides nucleation sites

Question 24

nucleation sites

Answer 24

divots on surface of boiling chip

Question 25

boiling chips facilitate the

Answer 25

even boiling of water in the flask prevents superheating

Question 26

what technique could monitor the formation of 4-aminophenol by excitation of electrons w/ high energy photons?

Answer 26

TLC

Question 27

thin layer chromatography (tlc)

Answer 27

monitors reactions

Question 28

what can be used to visualized results from TLC?

Answer 28

UV light but only if the reaction mixture can absorb the UV light

Question 29

UV light carries a large amount of

Answer 29

energy that excites electrons of UV chromophores to a higher E state

Question 30

UV chromophores includes

Answer 30

double and triple bonds carbonyls (C=O) nitroso groups alkyl halides conjugated systems

Question 31

aromatic ring in the starting material of the rxn (4-nitrophenol) and the product (4-aminophenol) is a

Answer 31

UV chromophore each compound can absorb UV light and appears on TLC place

Question 32

in mass spectrometry, a sample is

Answer 32

ionized by high energy electrons electrons do not change E levels

Question 33

an external magnetic field is applied to a sample in

Answer 33

NMR spectroscopy

Question 34

radio waves are used to

Answer 34

detect H atoms and excite them from the alpha-spin to the beta spin state radio waves are low in E

Question 35

gas chromatography requires

Answer 35

vaporization of a sample (phase change) not an electronic excitation

Question 36

Rf =

Answer 36

distance compound traveled from origin / distance from origin to solvent front

Question 37

TLC is a technique used to

Answer 37

separate compounds based on polarity

Question 38

mobile phase

Answer 38

organic solvent travels up the stationary phase via capillary action

Question 39

stationary phase

Answer 39

a thing absorbent place coated w/ silica

Question 40

low capillary action

Answer 40

low adhesive forces on top > high adhesive forces

Question 41

more capillary action

Answer 41

low cohesive forces on bottom > high adhesive forces on top

Question 42

components of a mixture travel up the plate at

Answer 42

different rates b/c of varying polarity

Question 43

in normal TLC, nonpolar compounds travel

Answer 43

further up the plate have less affinity for the polar stationary phase

Question 44

Rf value is always

Answer 44

less than 1

Question 45

smaller Rf =

Answer 45

more polar, less mobile compounds

Question 46

amide has more

Answer 46

H bond accepts

Question 47

amine is a

Answer 47

H bond donor and acceptor via only one electronegative atom (N)

Question 48

amide is a

Answer 48

H bond donor and acceptor via two electroneg atoms (O and N)

Question 49

O-H stretch (phenol)

Answer 49

3650-3200 cm-1

Question 50

C-C stretch

Answer 50

1600-1475 cm-1

Question 51

sp2 C-H stretch

Answer 51

3100 cm-1

Question 52

NH stretch (amide)

Answer 52

3550-3060 cm-1

Question 53

C=O stretch (amide)

Answer 53

1650 cm-1

Question 54

sp3 C-H stretch

Answer 54

3000 cm-1

Question 55

acetaminophen contains several functional groups including

Answer 55

phenol (hydroxyl group) aromatic ring amide (strong absorption in IR spectrum)

Question 56

carbonyl (C=O) group from an amide shows an absorption from

Answer 56

1690-1650 cm-1