4.1.2 Organic Chemistry 2

Question 1

Primary alcohol

Answer 1

The carbon attached to the OH group is attached to only 1 alkyl group

Question 2

Secondary alcohol

Answer 2

The carbon attached to the OH group is attached to 2 alkyl groups

Question 3

Tertiary alcohol

Answer 3

The carbon attached to the OH group is attached to 3 alkyl groups

Question 4

3 properties of alcohol

Answer 4

1. can form hydrogen bonds as there is a hydrogen bonded to an electronegative atom (NOF)
2. Soluble in water due to hydrogen bonds being able to bond with water (the longer the chain the less soluble)
3. Relatively low volatility compared with alkanes due to hydrogen bonding with other alcohol molecules

Question 5

Products of complete and incomplete combustion of alcohol.

Answer 5

complete- water and CO2
incomplete- CO, C and water
same as alkanes

Question 6

what is used to oxidise alcohols/refux

Answer 6

Potassium dichromate K2Cr2O7

Question 7

Oxidisation of primary alcohols with excess potassium dichromate

Answer 7

when heated under reflux they will first oxidise into aldehyde then further into carboxylic acid.

Question 8

Product of Oxidation of secondary alcohols

Answer 8

Ketones

Question 9

Oxidation of Tertiary alcohols

Answer 9

Will not be easily oxidised and have no reaction with potassium dichromate

Question 10

How to get a aldehyde from a primary alcohol

Answer 10

first reflux and distil the products to prevent further reactions.

Question 11

what is formed when water is removed from alcohol

Answer 11

alkenes

Question 12

Elimination/Dehydration of Alcohol

Answer 12

Heat with an acid catalyst (H3PO4 or H2SO4)
OH and adjacent H atoms are removed to form H2O and alkene

Question 13

Substitution reaction of alcohol with a Hydrogen halide, method, overall equation

Answer 13

heat alcohol under reflux with H2SO4 and a sodium halide.
the sodium halide will produce a hydrogen halide in situ.
alcohol + sodium halide + H2SO4 –> haloalkane + NaHSO4 + water

Question 14

Nucleophile definition

Answer 14

electron pair donor

Question 15

Reactivity of Haloalkanes

Answer 15

Halogens are more electronegative than carbon and therefore C-X bonds will be polarised, meaning they are able to react with nucleophiles.

Question 16

Nucleophilic substitution mechanism

Answer 16

Nucleophile approaches the haloalkane from the opposite side to the halogen, to minimise repulsion
Carbon halogen bond breaks by heterolytic fission
Alcohol and a halide ion are formed

Question 17

2 factors for speed of nucleophilic substitution

Answer 17

1. Tertiary, secondary or primary- tertiary haloalkanes will react the fastest and primary slowest due to the slightly different mechanism.
   2.Bond enthalpy- the higher the bond enthalpy the slower the reaction,

Question 18

Why are tertiary carbocations the most stable

Answer 18

Each alkyl group will push electron density towards the positive carbocation increasing stability.

Question 19

what are CFCs

Answer 19

Chlorofluorocarbons
Haloalkanes where are the hydrogen atoms have been replaced by either fluorine or chlorine.

Question 20

Properties of CFCs

Answer 20

Very stable
volatile
non-flammable
non-toxic

Question 21

Uses of CFCs

Answer 21

Fridges, aerosol cans, dry cleaning, air conditioning

Question 22

what is the ozone layer

Answer 22

area 10-40km above earth surface that absorbs harmful UV-B rays from the sun that cause skin cancer

Question 23

How is ozone formed

Answer 23

O2 molecules are broken down into radicals via UV.
These free radicals combine with O2 molecules create O3 (ozone) molecules.

Question 24

equation for the formation of ozone

Answer 24

O2 –> O’ + O’
O + O2 –> O3

Question 25

CFCs affect on ozone

Answer 25

create radicals in the upper atmosphere that act as a catalyst that destroys ozone molecules

Question 26

equations to show effect of chlorine radicals on the ozone.

Answer 26

Cl' + O3 --> O2 + ClO' ClO' + O' --> O2 + Cl' O3 + O --> 2O2

Question 27

NO radicals, production and eqauations in the ozone

Answer 27

Produced by aircraft engines and thunderstorms. NO' + O3 --> NO2' + O2 NO2' + O --> NO' + O2

Question 28

How does IR spectroscopy work

Answer 28

IR radiation causes covalent bond to vibrate more and absorb energy Different bonds absorb energy at different wavelengths This allows us to identify the bonds in a chemical

Question 29

uses of IR spectroscopy

Answer 29

Analysis of atmospheric gases monitor air pollution Breathalysers

Question 30

Limitations of IR spectroscopy

Answer 30

Only identifies the function groups and bonds has to be pure substance

Question 31

what is Mass Spectrometry used for

Answer 31

to find the mass of atoms can identify compounds

Question 32

How does Mass spectrometry work

Answer 32

VIADD the sample is first vaporised then Ionised by having high energy electrons fired at it. M + e- --> M+ + 2e- These ions are then Accelerated by a strong electric field The accelerated ions are Deflected by the Magnetic field ( the bigger ions are deflected less) The ions are then Detected.

Question 33

Fragmentation definition

Answer 33

as organic molecules do not hold charge well they fragment into smaller ions and neutral fragments. They do this in regular patterns meaning they can be analysed