PAPER 2 ALL Flashcards
(135 cards)
1
Q
which halogenoalkane reacts the quickest and why
A
- based upon the carbon-halogen bond strength
- C-F bond is highest, and so reacts the slowest, since it has a high bond enthalpy
- C-I bond has lowest bond enthalpy, and so is easiest to break, therefore reacts quickly
2
Q
enzymes are….
A
proteins which act as biological catalysts
- they catalyse every metabolic reaction in organisms
- contain an active site which is where the substrate fits in to
- the active site is 3d (part of tertiary structure)
3
Q
forms of chromatography
A
thin layer (TLC) - simple way of separating mixtures
column - to separate solutions
gas - to separate volatile liquids
4
Q
halogenoalkane -> amine
A
- ammonia ( :NH3 ) NO CHARGE
- warm, ethanolic
- nucleophilic substitution
- uses two NH3
5
Q
what is chemical shift measured against
A
TMS (tetra methyl silane)
- inert ( doesn’t react) , non-toxic, volatile (easy to remove)
- this has 12 hydrogen atoms all in identical environments, so produces a single peak far away
- used to calibrate
6
Q
what is a zwitterion
A
- a dipolar ion
- there is a positive and negative charge in different parts of the molecule
- they only exist near an amino acids isoelectric point
7
Q
what do the peaks on proton NMR show
A
number of peaks = number of environments
height of peaks (ratio) = number of hydrogens in each environment
splitting = adjacent hydrogens (-1)
shift (ppm) = specific environment
8
Q
excess hydrocarbon in FRS
A
- will remain as a singular halogenoalkane
9
Q
alkene -> addition polymer
A
- double bond opens up and joins to adjacent
- forms saturated molecules
- non-polar
- this makes them unreactive
10
Q
producing cyclohexene from cyclohexanol - step 1
A
distillation
- add sulfuric acid to round bottom flask containing cyclohexanol
- add anti-bumping granules
- heat to 83C - this is the boiling point of cyclohexene
- collect distillate from condenser in a cooled flask
11
Q
producing ethanol from glucose
A
- exothermic process
- uses yeast and anaerobic conditions
- 30 - 40 C
- C6H12O6 -> 2C2H5OH + 2CO2
- ethanol is separated by fractional distillation
12
Q
catalytic cracking
A
- zeolite catalyst
- slight pressure
- high temp (450)
- produces aromatic hydrocarbons and motor fuels
13
Q
evaluation of biofuels
A
+
- renewable (more sustainable)
- classed as carbon neutral
- petrol cars would have to be modified
- land used to grow fuel crops can’t be used for food crops
14
Q
recycling waste
A
- some plastics can be melted and remoulded
- others can be cracked into monomers, which can be used to make more plastics or other chemicals
15
Q
oxidising agent for alcohols
A
- acidified potassium dichromate
- turns from orange to green
16
Q
two kinds of polymers
A
- natural (DNA)
- synthetic (polyethene)
17
Q
excess chlorine in FRS
A
- will continue to attack the halogenoalkane, leading to dichloro, trichloro and tetrachloro compounds
18
Q
how is the carbocation from an acyl chloride substituted into a benzene ring
A
- electrons are attracted to the positive carbocation + bond
- this partially breaks the delocalised ring, and gives it a positive charge
- the negatively charged AlCl4- ion is attracted to the positive ring
- one chloride ion breaks away from the ion and bonds with the hydrogen ion
- this removed the hydrogen and allows the catalyst to reform, and HCl forms
19
Q
burying waste
A
- landfill is used when the plastic is difficult to separate, not in large enough quantities to be financially worthwhile or too technically difficult to recycle
- it is a cheap and easy method
- but it requires a lot of land
- it also produces methane
20
Q
what is biodiesel
A
- produced by reacting vegetable oils with methanol
- potassium hydroxide as a catalyst
- makes vegetable oils appropriate for engines
- leads to a mixture of methyl esters of fatty acids
21
Q
washing
A
a method of removing impurities
- for example, aqueous sodium hydrogencarbonate can be added to remove acid
- it produces CO2 which leaves the solid
22
Q
optical isomers are what
A
mirror images of each other
23
Q
how to remove water soluble impurities
A
separation
- pour into a separating funnel and add water
- shake and allow to settle
- organic layer and aqueous layer are immiscible
- open the tap and run off each layer into different containers
24
Q
halogenoalkane -> aliphatic amine
A
- heat with excess ammonia
- produces a mixture of 1 / 2 / 3 / 4 amines, because the primary amine acts as a nucleophile
25
formula for natural ozone formation
O2 = 2 O radicals (needs UV)
O2 + O radical = O3
26
acyl chlorides reactions always form
HCl
- the chlorine is easily lost
27
nucleophile
electron pair donor
negative
28
how does NMR work
- normally, the nuclei spin in random directions and so their magnetic fields cancel out
- when a strong external magnetic field is applied, the nuclei will either align or oppose the field
- those which align are at a slightly lower energy level
- radio waves of the right frequency can give aligned nuclei the energy to flip up to higher level
- the nuclei opposed can emit radio waves and flip down to lower level
- generally, there are more aligned, so NMR measure absorption of radio waves
29
formulas for ozone depletion
- the free radicals act as catalysts
Cl radical + O3 = O2 + ClO radical
ClO radical + O3 = 2O2 + Cl radical
overall = 2O3 = 3O2
30
nitrile -> aliphatic amine
reduction
1) use LiAlH4 (reducing agent) in a non-aqueous solvent (dry ether) followed by dilute acid
uses 4 [H]
2) use hydrogen gas with a metal catalyst like nickel at high temp / pressure
uses 2 H2
31
how to reverse condensation polymerisation
- hydrolysis
- water molecules are added back in
32
aliphatic vs aromatic
aliphatic = no benzene ring
aromatic = benzene ring
33
how to remove water from a purified product
- if separation is used, there will be traces of water left over
- add an anhydrous salt (e.g. magnesium sulfate or calcium chloride)
- the salt is used as a drying agent, and binds to any water present to become hydrated
- filter to remove drying agent
34
what do inhibitors do and how
slow down the rate of reaction
they have a similar shape to substrate
they bond to active site and block it from substrates
how much inhibition happens is dependent on concentrations of inhibitor and substrate AND how strongly the inhibitor bonds to the active site
35
acyl chloride reactions
- nucleophilic addition-elimination
- the reactant acts as a nucleophile ( H2O: / :OH- / :NH3 / CH3N:H2)
- it attacks the carbon on the acyl chloride, and the C=O tranfers to O
- then C=O reforms and Cl leaves
- Cl- bonds with hydrogen in new group
- HCl leaves
36
do racemates show optical activity
- no, the enantiomers cancel each other out
37
acyl chloride -> N-substituted amide
- violent reaction at room temp
- primary amines
38
how does cisplatin work
- cancer is uncontrollable division of cells
- in order to divide, it has to replicate DNA
- cisplatin binds to DNA, causing kinks which stop the proteins that replicate DNA from copying properly, and so it stops reproducing
- N atom on guanine forms dative bond with Pt ion, replacing cl ligand
- repeats with another guanine
39
how are polyamides made
- dicarboxylic acids and diamines
- carbonyl group react with amino groups
40
what is aspirin made of
- ester
- salicylic acid + ethanoic anhydride or ethanoyl chloride
- anhydride is preferred, as its less corrosive, slower reaction with water, doesn't produce dangerous HCl fumes
41
amiNe vs amiDe
amiNes = when one or more of the hydrogens in ammonia are replaced
amiDes = carboxylic acid derivatives. the OH is replaced by NH2
42
examples of non-plasticised polymers
- rigid PVC
- this is used for window frames and drainpipes
43
amino acids features
- basic amino and acidic carboxyl group
- this makes them amphoteric
- they are also chiral, so it will rotate plane polarised light
44
conditions for Friedel-crafts acylation
- heat
- reflux
- in a non-aqueous solvent (like dry ether)
45
three kinds of condensation polymers
- polyamides
- polyesters
- polypeptides
46
what reactions do benzene rings undergo
- ring has high electron density, so it attracts electrophiles
- typically electrophilic substitution
- never electrophilic addition, since the benzene ring is too stable to be broken
47
producing cyclohexene from cyclohexanol - step 2
separation
- transfer product mixture to a separating funnel
- add water (this dissolves soluble impurities)
- allow layers to settle, and drain lower layer (aqueous impurities)
48
acyl chloride vs acid anhydride
reactions are the same, but instead of forming HCl (like acyl chlorides), the acid anhydrides form carboxylic acids
they also react less vigorously
49
two phases of chromatography
- mobile: when molecules can move, either gas or liquid
- stationary: where the molecules can't move, may be a solid, or a liquid/gas on a solid support
50
racemic mixture contains
equal quantities of each enantiomer of an optically active compound
51
benzene -> nitrobenzene
- warm
- concentrated nitric and sulfuric acid
- electrophilic addition
- to keep it as only one nitro group, keep temperature below 55C
52
properties of polyalkenes
- usually non polar
- held together by only VD
- therefore, the longer the chain and closer they can get, the stronger the VDW forces
- therefore, long straight chains tend to be strong and rigid, whereas short and branched tend to be weaker and more flexible
53
column chromatography method
Stationary phase:
- pack a glass column with a slurry of absorbent material (e.g. aluminium oxide) coated with water
Mobile phase:
- a mixture is added to the top of the column and allowed to drain into the slurry.
- a solvent is then run slowly and continually down the column, this is the mobile phase
Analysis
- as the mixture is washed through column, the components separate according to solubility in mobile phase and how strongly they are adsorbed onto stationary phase (retention)
- more soluble = pass through quicker
54
what bonds hold proteins in shape
hydrogen
- these belong between polar groups and stabilise the secondary and tertiary structure
disulfide
- the amino acid cystine contains a thiol group (-SH). thiol groups can join together forming a disulfide bond (S-S)
55
gas chromatography method
- stationary phase is a solid OR solid coated by viscous liquid (like oil) packed into a long tube
- the tube is coiled to save space and built into an oven
- the mobile phase is an inactive carrier gas like nitrogen
- retention time depends on how much time the component spends moving with carrier gas, and how long it is stuck to viscous liquid
56
what is a soap
- the salt of a long chain carboxylic acid
57
carboxylic acid -> ester
- heat with alcohol
- in presence of concentrated sulfuric acid
- esterification (also condensation as it releases water)
58
evaluation of recycling waste
+
- reduces amount of waste going to landfill
- saves raw materials (like non-renewable oil)
- cost of recycling plastics is lower than making from scratch
- produces less CO2 than burning
-
- technically difficult
- collecting, sorting and processing is more expensive than other options
- can't remake the plastic, often have to make something else
- plastic can be easily contaminated
59
what causes the colour change in acidified potassium dichromate
orange dichromate ion ( Cr2O7 2-) being reduced to the green chromium (III) ion
60
ester -> alcohol
ACID:
- splits ino acid and alcohol
- must reflux with dilute acid
- reversible reaction, so need lots of water
BASE:
- splits into carboxylate ion and alcohol
- reflux with dilute alkali
61
chemical equations which show bioethanol to be carbon neutral
photosynthesis
- 6CO2 + 6H2O = C6H12O6 + 6O2
fermentation
- C6H12O6 = 2C2H5OH + 2CO2
combustion
- 2C2H5OH + 6O2 = 4CO2 + 6H2O
62
order of stability of carbocations
most stable = tertiary
least stable = primary
63
how do DNA pairs form
- hydrogen bonds
- A-T = 2 bonds
- C-G = 3 bonds
64
how do plasticisers work
- the molecules get between the polymer chains and pushes them apart
- this reduces the strength of the VDW forces, so they become more flexible
65
fehling's / benedict's solution
aldehyde = blue -> brick red
ketone = remains blue
- deep blue copper complexes which reduce to brick red Cu2O when warmed
66
what causes nuclear spin
any atomic nucleus with an odd number of protons and neutrons
this gives it a weak magnetic field
hydrogen nuclei are single protons, so they have spin
carbon usually has 6 neutrons and 6 protons, so it doesn't have spin.
however, 1% of carbon atoms are the isotope C13, with 6P and 7N, which does have spin
67
alkene -> alcohol
- H+
- solid phosphoric (v) acid catalyst
- 300C, 60 atm, steam
- hydration
68
strength of amines
lowest = primary aromatic amine
- the benzene ring draws electrons towards itself, so the lone pair gets partially delocalised
highest = primary aliphatic amine
- alkyl groups push electrons onto attached groups
69
polymer defintion
long chain molectules made of monomers
70
how to test for carboxylic acids
- add 2cm sample to test tube
- add spatula of solid sodium carbonate
- if it fizzes, bubble the gas through lime water
- if a carboxylic acid is present, it will produce CO2, which will turn limewater cloudy
71
alkene -> alkyl hydrogen sulfate
- sulfuric acid
- cold, concentrated
- electrophilic addition
72
factors which change the shape of proteins
- temperature
- pH
73
optical isomers and light
- normal light vibrates in all directions
- plane-polarised light only vibrates in one direction
- optical isomers rotate plane-polarised light (they are optically active)
- one enantiomer rotates clockwise, the other rotates anti-clockwise
74
thermal cracking
- high temp (700)
- high pressure (70 atm)
- produces lots of alkenes
75
how is soap made
- hydrolysis of veg oils and animal fats
- heat with sodium hydroxide
- produces gylcerol, soap and fatty acids
76
how to prepare tollens reagent
- 2cm of 0.1M silver nitrate (colourless)
- few drops of dilute sodium hydroxide solution
- should form light brown precipitate
- add drops of dilute ammonia until precipitate dissolves
77
carbonyl -> hydroxynitriles
- cyanide ion (CN-)
- ion must be acidified, since H+ ions are required in step 2
- nucleophilic addition
78
whats used instead of CFCs now
HFCs
hydrofluorocarbons
79
repeating unit vs monomer
repeating units have their double bonds open (like alkane) whereas monomers have double bond like alkene
80
DNA pairs
A-T
G-C
81
what solvents are used for proton NMR
- deuterated solvents, deuterium is an isotope of hydrogen that has 1P and 1N
- because its an equal number, it doesn't produce spin, and so doesn't produce a signal
- CCl4 doesn't contain any H so may be used
82
halogenoalkane -> nitrile
- cyanide ion ( :CN- )
- warm, reflux, ethanolic
- nucleophilic substitution
83
uses of esters
- have a sweet smell (perfumes)
- used to flavour foods
- polar liquids so used to dissolve polar organic compounds
- low boiling points and evaporate easily, making them good in glues and printing inks
- used as plasticisers
84
how to purify organic solids
recrystallisation
- add very hot solvent to impure solid until it dissolves (must be minimum amount)
- filter through a heated funnel to remove any insoluble impurities
- leave to cool
- remove crystals from liquid which contains soluble impurities by filtering under a reduced pressure (using a Buchner funnel)
- wash with ice cold solvent to remove soluble impurities from surface
- leave purified crystals to dry
85
halogenoalkane -> alcohol
- hydroxide ion ( :OH-)
- warm and aqueous
- nucleophilic substitution
- also called hydrolysis
86
impact of impurities on melting point
- the more impure a substance is, the melting point will be lower, and the range will be broader
87
three stages of free radical substitution
- initiation (radical is formed with UV light)
- propagation (free radicals are transferred
- termination (free radicals are cancelled out)
88
how to form fats and oils
- fatty acids combine with glycerol to form esters
- they can be saturated or unsaturated
89
levels of structure in proteins
primary - sequence of amino acids (polypeptide chain)
secondary - the peptide links can form hydrogen bonds with each other, forming either an alpha helix or b-pleated sheet
tertiary - the chain of amino acids is coiled and folded in a way which identifies the protein, giving it a 3d shape
90
which parts of the name of a carboxylic acid come from where
- first bit is from alcohol
- second is from carboxylic acid
HOWEVER, the formula is the other way around
91
producing cyclohexene from cyclohexanol - step 3
purification
- drain remaining cyclohexene into a round-bottomed flask
- add anhydrous CaCl2 (drying agent) and stopper
- allow to dry for 20 mins, swirl occasionally
- distill once more
92
disposal of polymers
ADDITION POLYMERS
addition polymers are made of non-polar carbon chains, which makes them unreactive and chemically inert
- this is an advantage when they are being used
- but they are non-biodegradable
CONDENSATION POLYMERS
- have polar bonds in their chains
- so are open to attack from nucleophiles
- therefore they can be broken down by hydrolysis
93
what is required for an optical isomer
- a chiral carbon
- this has 4 different groups attached to it
94
aldehyde / ketone -> alcohol
- requires a reducing agent
- NaBH4 (provides :H-) dissolved in water with methanol (to provide H+)
-nucleophilic addition
95
alkyl hydrogen sulfate -> alcohol
- add cold water and heat the product
- sulfuric acid acts as a catalyst
96
condensation polymers
- usually involves two different monomers, each with at least 2 functional groups
- each functional group reacts with a group on another monomer to form a link
- each time a link is formed, a water molecule is lost
97
what impacts a base's strength
- the availability of the nitrogen's lone pair of electrons
- more available = more likely to accept a proton = stronger base
a lone pair is more available if electron density is higher
98
DNA long word
de oxy ribo nucleic acid
99
quaternary ammonium salts
- quaternary ammonium ions are positively charged (N only needs 3 bonds)
- form complexes with negative ions to form quaternary ammonium salts
- used as catatonic surfactants
- hydrocarbon will bond to non-polar substances like grease, the catatonic head will dissolve in water, the ammonium ion will bind to reduce static
- used in hair products / fabric conditioners
100
alcohol -> alkene
- H+ ion
- concentrated sulfuric acid
- elimination (or dehydration)
- produces a mixture of water, acid, product and reactant
101
burning waste
- heat is used to generate electricity
- this process has to be controlled to reduce the release of toxic gases
- waste gases from the combustion are passed through scrubbers
102
cisplatin structure
Platinum (II) is central ion
surrounded by
- 2 chloride ion ligands ( :Cl )
- 2 ammonia ligands ( :NH3 )
in a square planar shape
103
whats the main issue with using acidified potassium dichromate and how to overcome
- it doesn't distinguish between primary or secondary alcohols
- therefore, in order to do so, you need to distill the alcohol and collect the distillate
- then test if it has been oxidised to an aldehyde (primary) or ketone (secondary)
104
how does DNA form
condensation polymerisation
- sugar phosphate backbone
105
acyl chloride -> ester
- room temperature
- vigorous reaction
- react with alcohol
106
acyl chloride -> carboxylic acid
- cold water
107
electrophile
electron pair acceptor
positive
108
friedel-crafts acylation of benzene theory
- used to add an acyl group to benzene ring
- normally, benzene is unreactive, and the acyl group allows for further reactions
- electrophile has to have strong positive charge to be able to attack the stable benzene ring
- therefore, a halogen carrier is used as a catalyst.
109
are amines weak or strong bases
- weak (they accept protons)
- the lone pair of electrons on the N atom which form a dative covalent bond with an H+ ion
110
animal fats vs vegetable oils
ANIMAL FATS
- mainly saturated
- fit together well (increased VDW)
- so requires higher temp to melt, so solid at room temperature
VEGETABLE OILS
- unsaturated
- chains cant bend, so can't fit together, leading to weaker DW forces
- therefore, have lower melting points and are liquid at room temperature
111
where do the bases in DNA bond
nitrogens:
adenine, cytosine and guanine = NOT next to double bond on pentagon
thymine = N without H bonded
112
halogenoalkane -> alkene
- hydroxide ions ( :OH-)
- warm, ethanolic, reflux
- anhydrous
- elimination
- OH acts as a base
113
halogen carrier method
AlCl3
- it accepts a lone pair of electrons from the acyl chloride
- as the lone pair is pulled away, the polarisation increases and a carbocation is formed
- this makes it a much stronger electrophile
RCOCl: + AlCl3 = RCO+ + AlCl4-
114
production of carbon monoxide in incomplete combustion word equation
hydrocarbon + oxygen = carbon monoxide + water ( sometimes + carbon dioxide)
115
how are polyesters made
- dicarboxylic acids and diols
- carbonyl groups react with hydroxyl groups
116
nitrobenzene -> aromatic amine
reduction
- heat nitrobenzene with tin and concentrated HCl under reflux
- this makes a salt
- use an alkali (like NaOH) to turn the salt into an aromatic amine
117
amino acid zwitterions in different conditions
ACIDIC
- gains a proton to form COOH
ALKALI
- loses a proton to form NH2
118
oxidation of ethanol required practical
- gently heat ethanol with potassium dichromate and sulfuric acid (acidifies)
- to produce the aldehyde, distill immediately
- to produce carboxylic acid, heat under reflux
- allows for volatile compounds to condense and re-enter the reaction mixture
119
what are plasticisers used for
to modify the properties of polymers, making them more flexible
120
production of carbon in incomplete combustion word equation
hydrocarbon + oxygen = carbon + water
121
example of plasticised polymers
- plasticised PVC
- used to make cable insulation, clothing and flooring tiles
122
oxidisation extent of alcohol types
primary = aldehydes (distill) then carboxylic acids (reflux)
secondary = ketones (reflux)
tertiary = don't oxidise
123
are carboxylic acids weak or strong acids
weak, only partially dissociates
124
carboxylic acid + carbonates
2CH3COOH + Na2CO3 = 2CH3COONa + H2O + CO2
125
formation of electrophile in nitration
HNO3 + H2SO4 = H2NO3+ + HSO4-
H2NO3+ = NO2 + + H2O
The NO2 + is the electrophile
126
what is a protein
condensation polymers of amino acids joined by peptide links
put together by condensation and broken by hydrolysis
in order to hydrolyse, you need hot, aqueous 6M HCl and to heat under reflux for 24 hours
127
overall reaction for bromoethane + ammonia
CH3CH2Br + 2NH3 = CH3CH2NH2 + NH4Br
128
how are nitrous oxides formed in a car engine
- due to high pressure and temperature
- nitrogen and oxygen atoms in the air react
129
tollens reagent
aldehyde = silver mirror
ketone = no change
- reduced to silver solid when warmed
130
acyl chloride -> amide
- violent reaction at room temperature
- ammonia
131
formula of a CFC
- no hydrogens, only fluorine or chlorine
132
alkene -> halogenoalkane
- hydrogen halide (e.g. HCl)
- electrophilic addition
133
DNA components
1- phosphate group
2 - pentose sugar
3 - a base
134
how to separate a water soluble product AND water soluble impurities
solvent extraction
- use organic solvent which the product is more soluble than in water
- add to solution and shake
- the product will dissolve into organic solvent, and impurities will remain in water
- solvent containing product can be run off using a separating funnel
135
what is a fatty acid
- long chain carboxylic acid
