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AQA A-Level Chem > Organic Year 12 > Flashcards

Organic Year 12 Flashcards

(51 cards)

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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

Study These Flashcards
A

Industrial

Catalytic

22
Q

What is thermal cracking

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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

Study These Flashcards
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

Study These Flashcards
A 
Carbon monoxide
Nitrogen oxides 
Sulphur dioxide
Carbon particulates 
Unburnt hydrocarbons
Carbon dioxide
Water vapour
25
Why is CO bad, how is it formed and what is done to reduce it
Formed from incomplete combustion of alkanes Bad as inhibits Hb so poisons people Reduced by catalytic converters I
26
Why is CO2 bad, how is it formed and what is done to reduce it
Produced by combustion of alkanes Greenhouse gas Prevented by reduced fossil fuel use
27
Why is C particulates bad, how is it formed
Produced by incomplete combustion | Causes respiratory issues, cancer and global dimming
28
Why are nitrous oxides bad and how are they formed
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
Why is SO/SO2 bad, how is it formed and what is done to reduce it
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
Why is Unburnt hydrocarbons bad, how is it formed and what is done to reduce it
Formed by unburnt fuels Irritant and greenhouse gas Reduced. H ensuring proper fuel mix
31
Why is water vapour a pollutant from crude oil
It acts as a greenhouse gas contributing to climate change
32
How does SO2 cause acid rain
Reacts with O2 and H2O in air to give H2SO4
33
What are the two methods of glue gas desulphurisation
``` 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
How do catalytic converters work
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
2 Equations to show catalytic converters working
2CO+2NO-> N2 + 2CO2 HCs + NO —> N2 + CO2 + H2O
36
How does the greenhouse effect work
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
What is the name of the reaction that forms haloalkanes from alkanes
Free radical substitution
38
What are the three steps of free radical substitution
Initiation Propagation Termination
39
What is the overall reaction for FRS of CH4 with Cl2
CH4 + Cl2 —> CH3Cl + HCl
40
What is the Initiation Step for Free radical sub
Cl2 —> 2• Cl UV Cl2 absorbs UV and breaks bond, e- are split in the middle so each Cl has lone e-
41
What is a free radical
Molecule with unpaired electron | Highly reactive
42
What are the propagation steps in Free radical substitution | Equation example
•Cl + CH4 —> •CH3 + HCl •CH3 + Cl2 —> •Cl + CH3Cl Radical and stable on each side
43
What are termination steps in free radical substitution
Involves two FR from propagation reacting together to give stable molecule Can be any free radicals
44
How is the ozone layer breaking down
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
Propagation steps to show ozone breakdown
* Cl + O3 —> •ClO + O2 | * ClO + O3 —> •Cl + 2O2
46
Why are haloalkanes polar molecules | What happens to polarity going down
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
What is the solubility of haloalkanes like
Bonds aren’t polar enough to be soluble | No H2 bonding
48
What is the boiling point of haloalkanes like and what effects it
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
What two factors determines reactivity of C-X bond in haloalkanes and which one is a more important factor
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
How does bond polarity determine C-X reactivity
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
How does bond enthalpy determine reactivity of C-X bond
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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