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AQA A-Level Chem > Organic Year 12 > Flashcards

Organic Year 12 Flashcards

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1
Q

How to calculate empirical formula

A

Calculate moles (mass/Mr)
Divide both by smallest number
Make whole numbers (round if close, of .5 multiply both by 2)

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2
Q

Aldehyde suffix and functional group

A

=O on end of molecule

Suffix -anal

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3
Q

Ketone suffix and functional group

A

Suffix -one

=O in centre of molecule

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4
Q

What are the three types of structural isomers

A

Chain
Position
Functional group

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5
Q

What is a chain isomer

A

Same molecular formula, different displayed

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6
Q

What is a position isomer

A

Functional group changes place

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7
Q

What is a functional group isomer

A

Changes functional group eg/ Alkene to cycloalkane

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8
Q

What are the two types of stereo/geometric isomerism

A

E/z and optical

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9
Q

What is E/Z isomerism

A

Position of high priority groups either side of c=c, fixed as c=c doesn’t rotate, same side is Z, opposite is E

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10
Q

Does the chain length effect reactivity of FG

A

No

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11
Q

Does chain length affect physical properties and give example

A

Yes

Eg/ bigger chain will increase mp as IMFs increase

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12
Q

What does branching do to MP

A

Reduces it as molecules pack together less well, so VdWs can’t act as strong

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13
Q

Does chain length increase or decrease isomer number

A

Increase

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14
Q

What is the polarity of alkanes like

A

Non polar
C and H have similar electro negativities
IMFs are only VDWs

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15
Q

What is the boiling point of alkanes like

A

Increases with chain length as higher IMFS

Decreases with branches as can’t pack together as close so vdws less effective

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16
Q

What is the solubility of alkanes like

A

Insoluble in H2O as H2 bonds in water are stronger than VDWS in alkanes

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17
Q

How is crude oil formed

A

Millions of years ago by plant and animal waste breakdown at high pressure and temp
Forms slowly therefore it is non renewable

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18
Q

What compounds are in crude oil and what effect does this have

A

Alkanes mostly but also other compounds like sulphur, reacting with air to form SO2, which causes acid rain

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19
Q

How does fractional distillation of crude oil happen

A

Vapourise crude oil in furnace
Pass into tower, hot at bottom and cold at top
Vapour moves up tower via trays containing bubble caps until they reach tray cooler than boiling point and condense and are piped off as liquid
Tar collects as liquid at bottom
No covalent bonds are broken, only VdWs

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20
Q

Why are alkanes cracked industrially

A

Short chain alkanes are in demand for fuel

Alkenes are needed to act as chemical feedstock to start reactions

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21
Q

What are the two types of cracking

A

Industrial

Catalytic

22
Q

What is thermal cracking

A 
High temp 900 degrees
High pressure 70atm
No catalyst
Forms alkenes and alkanes 
\+ = no waste as alkenes make polymers
-= cost as more energy
23
Q

What is catalytic cracking

A

Lower temp 450 degrees
Low pressure 1 atm
Uses zeolite catalyst made of aluminium oxide and silicon
Forms alkanes alkenes cyclic alkanes and branched alkanes
+ less expensive and safer
- catalyst is initially expensive but lasts long time

24
Q

Name all crude oil pollutants

A 
Carbon monoxide
Nitrogen oxides 
Sulphur dioxide
Carbon particulates 
Unburnt hydrocarbons
Carbon dioxide
Water vapour
25
Q

Why is CO bad, how is it formed and what is done to reduce it

A

Formed from incomplete combustion of alkanes
Bad as inhibits Hb so poisons people
Reduced by catalytic converters I

26
Q

Why is CO2 bad, how is it formed and what is done to reduce it

A

Produced by combustion of alkanes
Greenhouse gas
Prevented by reduced fossil fuel use

27
Q

Why is C particulates bad, how is it formed

A

Produced by incomplete combustion

Causes respiratory issues, cancer and global dimming

28
Q

Why are nitrous oxides bad and how are they formed

A

Formed when hot car (2000 degrees) engines combust fuel and the nitrogen formed reacts with O2 in air
NO further reacts to give NO2, which then forms nitric acid and therefore acid rain which corrodes limestone

29
Q

Why is SO/SO2 bad, how is it formed and what is done to reduce it

A

Fossil fuels contain sulphur impurities that form SO2 when burnt
It dissolves in water forming H2SO4 which makes acid rain - deforestation and corrosion of environment
Prevented by removal of SO2 by flue gas desulphurisation

30
Q

Why is Unburnt hydrocarbons bad, how is it formed and what is done to reduce it

A

Formed by unburnt fuels
Irritant and greenhouse gas
Reduced. H ensuring proper fuel mix

31
Q

Why is water vapour a pollutant from crude oil

A

It acts as a greenhouse gas contributing to climate change

32
Q

How does SO2 cause acid rain

A

Reacts with O2 and H2O in air to give H2SO4

33
Q

What are the two methods of glue gas desulphurisation

A 
SO2 + CaO + 2H2O + 0.5O2 —> CaSO4•2H2O + Co2
SO2 is in the gas
CaO is the solid compound used 
H2O is sprayed 
O2 comes from air

Other method is to use CaCO3 instead of CaO and H2O forms CaSO4 and CO2

34
Q

How do catalytic converters work

A

In all new cars to remove Co2, NO and HCs from exhaust gas mixture
Honeycomb structure coated with platinum, polodium and iridium to give a large surface area
The gas passes over and reacts to form less harmful products

35
Q

2 Equations to show catalytic converters working

A

2CO+2NO-> N2 + 2CO2

HCs + NO —> N2 + CO2 + H2O

36
Q

How does the greenhouse effect work

A

CO2 and other greenhouse gases trap IR so atmosphere heats up so earth sustains life
With additional ghgs this became too efficient and earth started warming

37
Q

What is the name of the reaction that forms haloalkanes from alkanes

A

Free radical substitution

38
Q

What are the three steps of free radical substitution

A

Initiation
Propagation
Termination

39
Q

What is the overall reaction for FRS of CH4 with Cl2

A

CH4 + Cl2 —> CH3Cl + HCl

40
Q

What is the Initiation Step for Free radical sub

A

Cl2 —> 2• Cl
UV
Cl2 absorbs UV and breaks bond, e- are split in the middle so each Cl has lone e-

41
Q

What is a free radical

A

Molecule with unpaired electron

Highly reactive

42
Q

What are the propagation steps in Free radical substitution

Equation example

A

•Cl + CH4 —> •CH3 + HCl
•CH3 + Cl2 —> •Cl + CH3Cl
Radical and stable on each side

43
Q

What are termination steps in free radical substitution

A

Involves two FR from propagation reacting together to give stable molecule
Can be any free radicals

44
Q

How is the ozone layer breaking down

A

ChloroFluoroCarbons (CFCs) are forming •Cl from UV reactions in atmosphere, then FR is reacting with O3, braking down the layer
CFCs are found in aerosols and fridge coolants

45
Q

Propagation steps to show ozone breakdown

A
  • Cl + O3 —> •ClO + O2

* ClO + O3 —> •Cl + 2O2

46
Q

Why are haloalkanes polar molecules

What happens to polarity going down

A

Contain polar C-X bond as halogens are electronegative delta - and carbons are delta plus
Polarity decreases going down group and group 7 molecules get less electroneg

47
Q

What is the solubility of haloalkanes like

A

Bonds aren’t polar enough to be soluble

No H2 bonding

48
Q

What is the boiling point of haloalkanes like and what effects it

A

Increases with chain length
Increases going down halogen group
Both because VDWs get bigger due to molecule getting bigger
Branches reduce Boiling point as can’t compact easily
Always higher than alkanes as higher Mr and more polar

49
Q

What two factors determines reactivity of C-X bond in haloalkanes and which one is a more important factor

A

Bond polarity and bond enthalpie
Bond enthalpy is more important as experiments have proved that reactivity increases going down group, just like bond enthalpy shows

50
Q

How does bond polarity determine C-X reactivity

A

X is more electroneg than C, so bond is polar, therefore C is electron deficient and can be attacked easily by nucleophiles (electron pair donor)
This would predict that C-F is most reactive as C-F is most polar so C+ has most +ve in C-F out of all halogens, so is most likely to be attacked and react

51
Q

How does bond enthalpy determine reactivity of C-X bond

A

C-X bond get weaker going down as atom size increases
so shared e- are further away from nucleus
therefore are broken easier
This would predict that C-F is least reactive as it is the strongest bond, and this is correct

AQA A-Level Chem (1 decks)

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