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Organic chemistry Flashcards

1
Q

How to distinguish enantiomer

A

Measure the optical activity with a polarimeter

rotate the plane of plane-polarized light in the same extent but in the opposite direction

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2
Q

test for -OH

A

X MnO4-

correct: Cr2O72-

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3
Q

why substance is soluble in organic solvents

A

the attractive force between molecules are of similar strength as those in organic solvents

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4
Q

use of aspirin

A

reduce fever
reduce risk of heart disease
painkiller
reducing inflammation(發炎）

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5
Q

principle of soup

A

detergent consists of a hydrophobic hydrocarbon tail and a hydrophilic ionic head
hydrophobic tail dissolve in grease
hydrophillic head dissolve in water, reducing surface tension
stirring cause the grease splits to tiny droplets
repulsion of negatively charged head to form emulsion
oil droplets become suspended in aq solution
easy to be carried away by water

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6
Q

observation of esters (2)

A

two immiscible layers are observed

A fruity smell is detected

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7
Q

which hydrolysis is more favourable

A

alkaline
acid hydrolysis is reversible but alkaline hydrolysis is irreversible. In alkaline hydrolysis, all reactants are completely converted into products

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8
Q

use of hexanedioic acid in industry

A

to make nylon 6,6

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9
Q

why hydrocarbon with smaller carbon content is better for a fuel

A

hydrocarbon with smaller carbon content has a smaller molecular mass and so has a lower boiling point and the molecular size is smaller.
So, it burns more completely.

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10
Q

is soap an ester?

A

No

there is only COO- ion but no RCOOR

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11
Q

how to convert alkene to alkane

A

Pass excess H2 to alkene in the presence of Pt

Catalytic hydrogenation

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12
Q

naming

halogen or double bond prioritize?

A

double bond

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13
Q

why HOOCCH2COOH can form a polymer with H2NCH2NH2 but cannot

A

HOOCCH2COOH has two COOH grouo to react with NH2 group in the diamine while CH3CH2COOH only has one COOH group

Each HOOCCH2COOH can react with two H2NCH2NH2 to form a chain but CH3CH2COOH cannot

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14
Q

what is aliphatic hydrocarbon

A

without benzene ring

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15
Q

what is aromatic hydrocarbon

A

with benzene ring

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16
Q

define isomers in general

A

isomers are compound having the same molecular formula but different arrangements of atom

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17
Q

what are the two types of isomerism

A

structural isomerism and stereoisomerism

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18
Q

define structural isomers

A

structural isomers are compound having the same molecular formula but different structural formula

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19
Q

define stereoisomers

A

stereoisomers are isomeric compounds having their atoms linked in the same way, but differ in the spatial arrangement of their atoms

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20
Q

why cis-trans isomers exist

A

it is because of the restricted rotation about a covalent bond

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21
Q

what is a chiral molecule

A

a chiral molecule is a molecule which is not superimposable on its mirror images. The chiral molecule and its mirror image are called a pair of enantiomers.

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22
Q

what is a chiral carbon

A

it is a carbon atom which is attached to 4 different atoms or group of atoms

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23
Q

enantiomers have identical chemical properties

T/F

A

90% correct

exception: enantiomers behave differently when they are reacted with a chiral molecule

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24
Q

enantiomers have identical physical properties

T/F

A

90% correct (mp bp and density)

except optical activity

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25
density of alkanes compare to water
it is less dense than water
26
requirement for substitution reaction
UV light or diffused sunlight direct sunlight should not be used
27
why cracking has to be carried out in the absence of air
cracking must be carried out in the absence of air because combustion occurs instead of craking in the presence of air
28
why alkene burns with more soot than an alkane with the same number of C atoms
C:H ratio or percentage by mass of C is higher for the alkene
29
what is the rule related to addtion reaction of HX
Markovnikov's rule | the H atom attaches itself to the C atom already carrying the larger no. of H atom
30
what are the examples of haloalkanes taht are denser than water
CH2Cl2 CHCl3 CCl4 CH3CCl3 other 99% less dense than water in dse
31
why an alcohol is soluble in water
it has a relatively short carbon chain | formation of H-bond with H2O molecules
32
when ketone add LiAlH4 then H+ | where the H atom is contribute to respectively
LiALH4 that H to 分開 that one | H+ that H to O 隔離 form OH
33
what are the uses of conc H2SO4 in esterification
catalyst | dehydrating agent in order to shift the eqm position to the right
34
what is chloroform
trichloromethane
35
what is acetone
propanone
36
what is acetic acid
ethanoic acid
37
what is formaldehyde
methanal
38
what is isopropyl alcohol
propan-2-ol
39
why COOH has a more extensive intermolecular H-bonds
as RCOOH has 1 more electronegative O atom than ROH and so there are more lone pair electrons on NOF
40
which one has a higher bp | H2O2 or H20?
H2O2 | as it has more lone pair electrons and thus more extensive H-bonds
41
acid hydrolysis or acidic hydrolysis
acid hydrolysis!!!!
42
compare the density of ester with water
usually less dense | so ester float on water when they are not miscible
43
why alkaline hydrolysis can always goes to completion
its because the RCOOH formed is immediately removed by reaction with OH- so the eqm position of the first reaction goes to right first reaction: ester + water to acid + alcohol
44
what are the smells of amines
amines of lower molecular masses have characteristic ammonia smell while larger amines have fishy smell
45
how to distinguish ester and amide
heat with NaOH ester: no observable change at first then 2 layers become miscible amide: colorless gas bubbles evolved which turn moist pH paper blue (becuz of NH3)
46
why the yield of most organic reactions are less than 100%
incomplete reaction side-reactions presence of impurities in reactants loss of product during the course of the experiment
47
what is the use of recrystallization
it is used to purify solid products by removing impurities of different solubilities
48
what is the requirement in choosing the solvent in recrystallization
the solid product should be dissolved readily in a hot solvent but is much less soluble in the cold solvent All other impurities must either be insoluble or remain in solution in both cold and hot solvent it should be volatile so that it is easier to be removed it should not react with the product
49
describe the procedure of recrystallisation
a suitable solvent is chosen (which there isn't any reaction between the solvent and product) minimum volume of hot solvent is used to dissolve the solid impure product the mixture is filtered to remove insoluble impurities the filtrate is allowed to cool slowly so that crystals can reform, with soluble impurities staying in the cold solvent crystal can be obtained by filtration
50
what is the consequence for using excess hot solvent to dissolve the impure solid sample during recrystallisation
the product may not seperate out as crystals if too much solvent is used
51
why the water should be going inside the condenser at the lower point
to ensure the water jacket is fully-filled with water and thus there are better cooling and condensing effect
52
why the thermometer bulb is level with the side arm during distillation
the temperature of the vapour is measured when it leaves the flask
53
what is the common name of aspirin
acetylsalicylic acid
54
define detergents
a detergent is a substance which improves the cleansing ability of water by acting as a wetting agent and an emulsifying agent
55
what is the source of soapy detergent
hydrolysis of animal fat
56
what is the source of soapless detergent
they are obtained from a series of reactions of petroleum fractions
57
what do wetting agents do
it can lower the surface tension of water so that the water can spread over the surface and penetrate into the things and wash away the dirts
58
what is the other term of alkaline hydrolysis of fat or oil
saponification
59
how to obtain the soap after saponification
add concentrated NaCl solution to make the soap be less soluble in water the process is known as salting-out
60
why concentrated H2SO4 can remove the fat blocking the drain pipes
it can perform acid hydrolysis and form alcohol and acid which can be easily removed by running water
61
what are the raw materials in manufacturing soapless detergents
1. petroleum fractions 2. conc. H2SO4 3. Conc NaOH
62
can soapy detergents works well in acidic solution
no | -COO- will form fatty acid with H+ which is insoluble in water
63
is soapy detergents biodegradable
yes
64
is soapless detergents biodegradable
not a must
65
nylon 6,10 6 represents? 10 represents?
6 is for diamine (前者） | 10 is for dioic acid（後者）
66
uses of nylon
ropes fishing lines strings for tennis racket
67
uses of polyesters
water bottle | clothings
68
definition of addition polymerization
monomer molecules are joined together to form polymer chains without losing any atoms
69
definition of condensation polymerization
monomer molecules are joined together to form polymer chains with the loss of small molecules
70
compare the melting point of cis-trans isomers
the melting point of a substance depends on intermolecular attraction as well as molecular symmetry trans-isomers are more symmetrical in shape and can better fit to solid lattice so it has a higher melting point
71
why sodium benzoate is more soluble than benzoic acid in water
sodium benzoate is an ionic compound which has stronger interaction with water while benzoic acid exists as molecules which have weaker intermolecular interactions with water
72
side effect of aspirin
increase bleeding | stomach upset

chem (14 decks)

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