paper2

Question 1

what is nmr and what is it used for

Answer 1

Nuclear magnetic resonance spectroscopy

used to analyse organic molecules

Question 2

what are the 2 diff types of nmr spectroscopy

Answer 2

carbon-13
tells how carbon atoms are arranged
hydrogen-1 / proton
tells how hydrogen atoms are arranged

Question 3

rules for both types of the nmr

Answer 3

1) number of peaks
- tells us how many non equivalent environments there are

2) chemical shift
measure of energy difference depends on what is near by to the environment

Question 4

rules for just proton nmr

also high res proton nmr

Answer 4

1) intergration trace
area under graph is equal to the number of hydrogen atoms

2) splitting pattern
singlet - one peak
no neighboring hydrogen

doublet - two peak
one neighboring hydrogen

triplet - three peak
2 neighboring hydrogen

quartet - four peak
3 neighboring hydrogen

multiplet - many peak
many neighboring hydrogen each side

Question 5

what considerations about solvents should be used in nmr
give 2 examples of solvent

Answer 5

mustn’t interfere with spectra

polar sample -polar solvent
CDCL3 d= heavy hydrogen

non polar sample - non polar solvent
tetrachloromethane
CCl4

Question 6

whats used as the standard in nmr and why is it used

Answer 6

TMS

4 methyls around a silicon

all the hs and cs are in the same environment so make one peak
chemical shift value of 0 and everything else is compared to this

• it is also inert and wont react with sample creating confusing peaks
• highly volitile easy to seperate from the solution and reuse
• non toxic so cause no harm

Question 7

key labels on the spectra

Answer 7

more up field to the right are more shielded

more downfield to the left are more deshielded

Question 8

measuring change gas produced

Answer 8

use gas syringe

Question 9

what does collision theory state
how can this effect rate of reaction

Answer 9

for a chemical reaction to take place the particles need to collide with each other in the correct orientation and with enough energy

if enough energy and correct orientation then there will be a successful collision

Question 10

define activation energy

Answer 10

minimum amount of energy for reaction to take place

Question 11

define a catalyst

Answer 11

catalyst is a substance that increases the rate of reaction without taking part in the chemical reaction by providing the particles an alternative mechanism with a lower activation energy

Question 12

define rate of reaction

give units

Answer 12

the speed at which a chemical reaction takes place

mol dm-3 s-1
mol dm-3 min-1

Question 13

factors affecting rate of reaction

Answer 13

temperature increase more particles with higher kinetic energy more frequent collisions and therefore higher probability of more successful collisions

concentration increase
result in an increased collision frequency and therefore an increased rate of reaction

pressure is increased
molecules have less space in which they can move
number of successful collisions increases due to an increased collision frequency

adding catalyst
decrease the ea of a reaction by providing alternative energy pathway

Question 14

what do maxwell-boltzman distribution curves display

Answer 14

a graph that shows the distribution of particle energies at a certain temperature

Question 15

describe key features of maxwell-boltzman distribution curves

Answer 15

large peak at lower energy this is the most probable energy

the right never touches x axis as its impossible for 0 particles can have high energy

the higher the temp the more particles with sufficient ea

Question 16

whats the general rate equation

Answer 16

Rate = k * [A]m * [B]n

where m and n are the orders of reaction with respect to reactants A and B
k is the rate constant.

Question 17

how are the orders represented in the rate eq using [ a ]

Answer 17

1st order = [ a ]

2nd order = [ a ]2

0 order = not written in rate eq

Question 18

what are the only values for the orders and what do they look like on graphs
and what are the values on axis

Answer 18

1st order linear

2nd order exponential

0 order a strainght horizontal line

y axis = rate
x axis = conc of reactant

Question 19

calculating k in rate equation

Answer 19

k = rate / conc of reactants to their powers
rate = mol dm-3s-1
conc = mol dm-3

overall units cancel out

Question 20

working out orders from the list of numbers

Answer 20

1) identify a test where only one reactant changes
2) find out how much it changed by(2x 3x 4x 0.25x)
3) rate = multiple of change to the power of x
4) find how you would get from order to rate number

Question 21

identifying orders when both conc are changing

Answer 21

1) identify the one condition where only one changes and work out the order for that reaction
2) look where both the conc change and then find the multiplication of both
3) multiply the known value factor by its power and then divide the rate factor by this value
4) now left with rate = [ B ]x figure out the x

Question 22

two ways of expressing Arrhenius equation

Answer 22

k = Ae-EA/RT

ln k = ln A – EA/(RT)

Question 23

what are the units for Arrhenius constant

Answer 23

the exact same as k

Question 24

how to identify the rate determining step from reaction mechanism

Answer 24

Mechanism
Step 1 A + B ~> X + D fast
Step 2 X + C ~> Y slow
Step 3 Y + B ~> E fast

its the slow step so the rate equation would be

r = k[A] [B] [C]
as they appear once in the reactant side so will be first order and d appears once on each side so cancels out

Question 25

define homulogous series

Answer 25

same funct group diff length of carbon chains

Question 26

whats displayed formula

Answer 26

every bond in the molecules is shown

Question 27

whats skeletal formula

Answer 27

lines for carbons add funct groups on but no hydrogens on chains shown

Question 28

structural formula

Answer 28

written as they are ch3ch2ch2ch2oh

Question 29

rules for naming

Answer 29

1) find longest carbon chain 2) identify side branches and funct groups 3) chain is numbered so part with highest prority has the lowest number 4) use di,tri,tetra for more than one type of the same thing 5) commas between numbers and hyphens between words and letters

Question 30

describe process of homolytic fission and the mechamism that uses this

Answer 30

nitiation 1) uv light shone at the Cl2 2) breaks the bond equally each element get one e- form free radicals propagation - Cl radical takes H off methane ~> HCl + methane radical - methane radical + Cl2 ~> chloromethane + Cl radical termination 1) two radicals bond form a non radical methane rad + methane rad ~> ethane Cl rad + Cl rad ~> Cl2 methane rad + Cl rad ~> chloromethane

Question 31

whats a structural isomer definition and three types

Answer 31

structural = same molecular formula different structures position = same molecular formula different position of funct group chain = same molecular formula different arrangement of carbon chains funct group = same molecular formula different funct group

Question 32

whats sterioismoreism and what examples

Answer 32

sterioisomerism = same molecular formula different arrangement in space e/z isomerism = different arrangement around a c=c priority groups determined by atomic number optical = a chiral carbon is when there are 4 diff groups bonded to one central atom form 2 mirror images / enantiomers rotate polarised light in opposite ways if in equal quantities then this is called a racemic mixture

Question 33

fract dist of crude oil

Answer 33

crude oil is many diff length hydrocarbons longer = higher bp seperates out at diff condensing points

Question 34

whats cracking and what are the two types

Answer 34

turning long chain hydrocarbons into shorter more useful ones catalytic- zeolite catalyst 450°c press just above 1 atm branched alkanes / aromatics thermal 400-900°c 7000kPa many alkenes

Question 35

complete combustion (excess o2)

Answer 35

alkane + o2 ~> co2 + h2o co2 and h2o vapour both greenhouse gasses

Question 35

incomplete combustion (limited oxygen)

Answer 35

alkane + o2 ~> co + h2o co is a toxic gas h2o vapour is a green house gas

Question 36

incomplete combustion (little to no o2)

Answer 36

alkane + o2 ~> c + h2o c is soot h2o vapour is a green house gas

Question 37

reactions happening in catalytic converters

Answer 37

2NO(g) + 2CO(g) ~> N2(g) + 2CO2(g) unburnt hydrocarbon + NO ~> CO2 + N2 +H2O

Question 38

nucleo sub

Answer 38

nucloephile = e- pair donor OH- NH3 -CN Aqueous solvent attack the carbon bonded to the halogen and the bond between halogen and carbon breaks going to the halogen makes g7- for nh3 another nh3 will come and take a H off forming NH2 and NH4+

Question 39

reactions of haloalkanes

Answer 39

iodine weak attraction bromine chlorine flourine strong attraction reactions with F are slow as there is high bond strength take lot of energy to break reaction w I go fast as there is weak bond strength take little enrgy to break

Question 40

elimination reaction Halogenoalkane -> Alkene

Answer 40

metal hydroxide w a alcohol condition KOH Warm ethanol solvent OH- attacks the hydrogen on the carbon bonded to the other cabon with halogen 1)this gives lone pair to hydrogen forms h2o 2) e- shared from the c-h gets donated to the c-c bond forms c=c 3) e- in the c-halogen bond donates its pair to the halogen form g7-

Question 41

substitution reaction

Answer 41

metal hydroxide w a aqueous condition

Question 42

electrophillic addition

Answer 42

happen at a c=c as these are dense in e- reagents 1) hbr 2) br2 test for alkenes 3) cold conc h2so4 stage 2 warm water 1) double bond is dense in e- and H is delta +ve and gets donated e- from the double bond and bonds to the c with most H's attached and the other c forms +ve carbocation e- donated from the Br- to the carbocation has to bond to most stable one +ve inductive effect 2) double bond is dense in e- and Br becomes delta +ve and gets donated e- from the double bond and bonds to the c with most H's attached and the other c forms +ve carbocation e- donated from the Br- to the carbocation has to bond to most stable one +ve inductive effect 3) H - O bond is polarised and the h is delta +ve and gains e- from the double bond and the - :OSO2OH- gives its e- pair to the +ve carbocation

Question 42

oxidation of alcohol

Answer 42

primary alc ~> aldehyde ~> carboxylic acid secondary alc ~> ketone tertiary alc ~> no reaction ox agent is potassium dichromate cr2o7^-2 turn from orange to green

Question 42

depletion of ozone

Answer 42

cfc are dangerous molecules that consist of a central carbon and 2F + 2Cl 1) initiation CF2CL2 ~UV~> CF2CL rad and Cl rad 2) propogation - o3 + Cl rad ~> ClO rad + O2 - ClO rad + o3 ~> 2o2 + Cl rad 3) termination - 2Cl rad ~> Cl2 hole in protective layer of the atmosphere means we are no longer protected from uv

Question 42

production of alcohol advantages

Answer 42

1) hydrogenation of ethene - e- rich c=c bond in ethene gets attacked by the H+ - carbocation is formed h20 bod to this and the o has a +ve charge one of the H's donate its e- pair and break off forming ethanol and H+ - h3po4 catalyst - 300°c - 70 atm of pressure - use steam advantages - fast - continous process - pure product disadvantages ethene from crude oil non-renewable resource will run out - very expemsive 2) fermentation of sugars glucose ~> ethanol + co2 yeast anaerobic coditions no air 30-50°c for yeast to work advantages - sugar is renewable - low technology used in low income countries disadvantages - batch process slow labourous - impure need to be further distilled

Question 43

polymerisation of organic molecules

Answer 43

have an alkene draw as a alkane in square brackets with the other connections going past the bracket and just put poly-before the alkene name

Question 43

elimination reactions w an alcohol or dehydration

Answer 43

conc h2so4 under reflux - h+ bond w lone pair on the oxygen and then this h2o molecule breaks off due to being +vely charged - carbocation produced and the h on adjacent c break off give e- pair to the c-c and this forms c=c give alkene + h+ + h2o

Question 43

ethanol use as bio fuel how its "carbon neutral"

Answer 43

photosynthesis takes in 6 molecules of co2 6co2 + 6h2o ~> c6h12o6 + 6o2 and in the fermentation c6h12o6 ~> 2c2h5oh + 2co2 in combustion 2C₂H₅OH + 6O₂ → 4CO₂ + 6H₂O so overall the co2 cancel however this wont be true as the transport will produce co2

Question 43

test for haloalkanes

Answer 43

add nitric acid and then silver nitrate +ve result is colour change white cream yellow ppt

Question 43

whats distrllation and reflux how do they look and what is produced

Answer 43

distillation heat conical flask of solution it evapourate and goes down condensing tube (water flow in from bottom) distillation of primary alc ~> aldehyde distillation of secondary alc ~> ketone distillation of tertiary alc ~> no reaction reflux condenser is vertical (water in from lowest point ) reflux of primary alc ~> carboxylic acid reflux of secondary alc ~> ketone reflux of tertiary alc ~> no reaction

Question 43

whats tollens used for

Answer 43

form silver mirror in presence if an aldehyde [Ag (nh3)2 ]+ form solid silver

Question 43

whats feighlings used for

Answer 43

blue sol ~> red ppt in presence of an aldehyde

Question 43

condensation of glycerol and fatty acid chains

Answer 43

...h h-c-oh ho-c = o h-c-oh ho-c = o h-c-oh ho-c = o ...h ho c = o (carboxyl) forms an ester a bond around an o atom and 3x h2o

Question 44

test for carboxylic acid

Answer 44

add sodiumhydrogen carbonate and if positive then co2 gas produced and bubbles will be created

Question 44

nucleophillic addition from o=c ~> alcohol

Answer 44

NaBH4 in aqueous solution :h- ion attack the c with the c=o forms a :o- the h+ accepts these e- and then forms alcohol

Question 44

uses of esters

Answer 44

- sweet smelling - solvents for polar molecules - plastics and polymers

Question 44

test for alkene

Answer 44

add bromine water brown/ orange solution ~> colourless

Question 44

saponification reactions in triglyceride

Answer 44

under alkaline conditions NaOH / KOH the h will reform alcohol on the glycerol and the metal+o on the fatty acid will form a soap by bonding to the +c=o

Question 44

acid anyhdride reacting w water what prod + conditions

Answer 44

2 x carboxyl groups room temp only need water

Question 45

production of bio diesel

Answer 45

methanol + triglyceride ~> glycerol + methyl esters methyl esters are the bio desiel

Question 46

acid anyhdride reacting w alcohol what prod + conditions

Answer 46

ester + carboxylic acid room temp only need alcohol

Question 47

acid anyhdride reacting w ammonia what prod + conditions

Answer 47

primary amide nh2 and carboxylic acid room temp only need ammonia

Question 48

acid anyhdride reacting w amine what prod + conditions

Answer 48

n substituted amide + carboxylic acid room temp only need amine

Question 49

nucleophillic addition elimination

Answer 49

1) nucleophile attacks the c=o carbon 2) the c=o break giving e- to the O become :O- and e- in the c-cl bond are given to the cl and breaks off forming :Cl- the nucleophile also becomes +vely charged 3) c=o reforms and a H off the nucleophile break off giving e- to the nucleophile

Question 50

acyl chloride + water what prod + conditions

Answer 50

carboxylic acid and HCl room temp only need water

Question 51

acyl chloride + alcohol what prod + conditions

Answer 51

ester + HCl room temp only need alcohol

Question 52

acyl chloride + ammonia what prod + conditions

Answer 52

amide + HCl room temp only ammonia

Question 53

structure of benzene

Answer 53

c6h6 with 6 delocalised p e- form a pi ring planar hexagon

Question 53

acyl chloride + amine what prod + conditions

Answer 53

n substituted amide and HCl room temp only need amine

Question 54

whats the kekele structure

Answer 54

cyclohexa-1,3,5-triene alternation c=c in a cyclic hexagon

Question 55

how was kekeles structure proven wrong

Answer 55

1) all the bond lengths are the same when viewed by a the lengths are inbetween the length of the c-c and the c=c 2) benzne is more stabe than kekeles when studying the enthalpy of hydrogenation shows the pi ring improves stability less energy locked up in the molecule 3) benzene doesnt react w bromine water suggesting there are no double bonds

Question 56

nitration of benzene making the no2+ conditions

Answer 56

1) h2so4 + hno3 ~> h2no3+ + hso4- 2) h2no3+ ~> h2o + no2+ mechanism 1) no2+ receive e- pair from the pi ring in benzene pi ring breaks into horse shoe 2) hso4- will take the h bonded to the same c that has no2 on and the e- pair between the c-h goes into the ring and reforms pi ring reflux 60 degrees c h2so4 catalyst

Question 57

freidel crafts acylation formation of the elecrophile conditions catalyst

Answer 57

forming electrophile - acyl chloride + AlCl3 ~> AlCl4- and o=c+ elecrophillic substitution reaction 1) benzene ring give e- pair to the +ve c=o and this forms a horse shoe 2) AlCl4- comes and takes the h away that was bonded to the c with the c=o attached 3) reform AlCl3 and from HCl and a benzene with a c=o and the rest of organic molecule attached

Question 58

Addition polymers

Answer 58

The c=c extends outside the brackets very stable don’t biodegrade

Question 59

Factors affecting the strength between addition polymers

Answer 59

Surface contact less chains stronger vdw Permanent dipole dipole Hydrogen bonding Addition of plasticisers Inbetween chains weakening intermolecular forces and this makes them more flexible

Question 60

Classification of amines

Answer 60

1° - 1 c-n. 2n-h. 1 lp 2° - 2 c-n 1n-h 1lp 3° - 3c-n. 0n-h. 1lp 4° - 3c-n. 0n-h. 0lp. And a +ve and the ion making salt

Question 61

What are quaternary ammonium salts used for

Answer 61

Shampoos and laundry detergent as they attract -ve ions

Question 62

Amines use as bases

Answer 62

Form dative covalent bonds with h+ giving both e- in line pair become +ve charged

Question 63

Why are aromatic bases weak

Answer 63

As the aromatic ring results in the line pairs being drawn in and partially delocalised less available for donation

Question 64

Factors affecting amine base strength

Answer 64

Positive inductive effect of the alkyl groups bonded result in e- being more available for donation

Question 65

Synthesising amines

Answer 65

1) React halogenoalkane with excess ammonia Nucleophillic substitution nh3 attack the c-g7 and then g7 leaves create c-nh3+ another ammonia comes and takes h+ form c-nh2 and (nh4+cl-) This reacts further making 2°,3°4° and amine can act as nucleophile 2)reducing nitriles a}Ni catalyst and h2 gas catalytic hydrogenation Nitrile + h2 -> amine b} lialh4 strong reducing agent and dry ether solvent Nitrile + 4[H]-> amine

Question 66

Condensation reaction

Answer 66

Joining of two monomers and forms a bond releases a small molecule either h2o or hcl

Question 67

Bonds in condensation polymers

Answer 67

Polypeptide = carboxyl and amine peptide or amide bond Nucleotide = phosphodiester

Question 68

Naming amines

Answer 68

Amino- = -Amine =

Question 69

Reactions between diol and dicarboxylic acids

Answer 69

Form ester bond in condensation reaction forms polyester

Question 70

Reactions between diamine and dicarboxylic acids

Answer 70

Form amide bonds or peptide bonds condensation reaction

Question 71

Uses of Kevlar

Answer 71

Kevlar is made from diamino benzene and benzene dicarboxylic acid Chains are linear and can pack very closely h bonds between chains and lots of vdw forces

Question 72

Repeating unit

Answer 72

All polymers involved minus the oh and h that are involved in bonding the lines go through the ()n

Question 73

Uses of nylon 6,6

Answer 73

Diamino hexane react w hexanedioic acid formed in condensation

Question 74

Uses of teryline

Answer 74

Benzene dicarboxylic acid and ethane diol condensation reaction forms a polyester

Question 75

Hydrolysis reactions

Answer 75

Condensation polymers can be split into separate monomers using water producing original monomers

Question 76

Why can’t poly alkenes be broken down Other ways of managing them

Answer 76

-Too stable so get moved to land fill or -just burn it can be used to generate electricity however this release many dangerous fumes - recycle the plastics melt down and remould into something else

Question 77

What do amino acids consist of And 2 property of amino acids

Answer 77

Carboxylic acid Amine R group They are amphoteric forming zwitter ions Typically chiral form enantiomers

Question 78

What’s a zwitter ion

Answer 78

Nh3+ form and coo-

Question 79

Amino acids at low ph

Answer 79

Cooh and nh3+

Question 80

Amino acids at high ph

Answer 80

Coo- and nh2

Question 81

Using tlc to identify amino acids

Answer 81

- Silica gel acts as stationary phase - Mobile phase is a liquid solvent - leave to rise up paper and mark the solvent front - solubility depends on affinity to the stationary phase least soluble lower down - spray with ninhydrin or fluorescent dye and uv light - calculate rf value and compare to other values of amino acids

Question 82

Protein hierarchy

Answer 82

1°- specific sequence of amino acids 2°- h bonds form between the backbone form beta pleated sheet or alpha helix 3°- specific shape hydrogen, disulphide, ionic bond between r groups 4°- many protein chains come together and bond

Question 83

What are enzymes and how do they work

Answer 83

A protein structure with specific active site only complementary to a specific substrate due to it being chiral active sites are known as stereo specific

Question 84

Preventing rate of enzyme controlled reactions

Answer 84

Add complementary inhibitors of active site

Question 85

Structure of one nucleotide

Answer 85

The oh on the phosphate for ester bond with the Pentose sugar eventually form sugar phosphate back bone of phosphodiester bonds The other oh bond to the nh on base and release h2o H bonds between lone pairs and hydrogen on bases

Question 87

Anti cancer drugs

Answer 87

Cis-platin Central pt Nh3 x2 on same side Cl x2 on same side Square planar shape Cl- bonds easily break off and the pt make two bonds to guanine bases Binds to the sugar phosphate backbone and makes it no longer complementary and prevents the replication of the dna preventing mitosis

Question 88

Limitation of cisplatin How to limit this side effect

Answer 88

Can bind to healthy cells and prevent replication of healthy cells - inject directly to the area of cancer - use lower doses of drug