Organic Chemistry

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What are the features of a homologous series?
Same functional group, same chemical properties, differ by CH2
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Explain how the boiling point of alkanes changes as the number of carbons increases
As the no. of carbons increase, the boiling point increases due more london forces therefore more energy needed to overcome them.
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Describe the temperature gradient in the fractionating column
As you go down the column the temperature increases
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What is a fraction?
The different compounds within crude oil that have different boiling points.
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State the property of the molecules in crude oil which allows the mixture to be separated into fractions
Different lengths and therefore different boiling points
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Describe the crude oil separation process in fractional distilliation
1. Oil is pre-heated then passes into the column (vaporised at 400 degrees) 2. The fractions condense at different heights because the temperature decreases upwards. 3. The separation depends on boiling point 4. Smaller molecules condense together at the
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What is the order of fractions from top to bottom?
1. Refinery Gases
2. Gasoline Gas (Petrol and Naphtha)
3. Kerosene
4. Diesel
5. Fuel Oil
6. Bitumen
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What is cracking?
When longer carbon chains are broken down to form smaller more useful molecules. The C-C bonds break in order to do this, which requires harsh reaction conditions.
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What is thermal cracking?
Thermal cracking produces a high proportion of alkanes and alkenes. High temperatures (1200K) and pressures (7000 kPa) are used to crack the carbon chains. The reaction always forms an alkane and the remaining atoms form at least one alkene.
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What is catalytic cracking?
Catalytic cracking produces aromatic compounds with carbon rings. Lower temps around 720K are used along with normal pressure but a zeolite catalyst is also used.
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What is produced when alkanes undergo combustion?
Carbon Dioxide and water
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If there isn't enough oxygen, what is formed and why is it dangerous?
Incomplete combustion occurs and carbon monoxide is formed which is a toxic gas. It is dangerous because it binds haemoglobin instead of oxygen which causes people to suffocate.
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What by-products of alkane combustion form acid rain?
Oxides of nitrogen and sulphur react with water which form dilute acids (acid rain)
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How does a catalytic converter work?
Harmful gaseous products can be removed using a catalytic converter. It uses a rhodium catalyst to convert harmful products into more stable products such as CO2 or H20.
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What is reforming?
It is the processing of straight-chain hydrocarbons into branched-chain alkanes and cyclic hydrocarbons for efficient combustion.
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What are alternative fuels?
These are biofuels that release fewer
harmful products. They are sustainable and won't run out.
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Advantages of bio fuels
1. reduction of use of fossil fuels
2. renewable
3. more carbon-neutral
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Disadvantages of bio fuels
1. Less food crops may be grown
2. Rain forests have to be cut down to provide land
3. Shortage of fertile soils
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Why do branched-chain isomers have lower boiling points and densities?
Smaller surface area for london forces to form therefore weaker london forces which require less energy to overcome
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What is homolytic fission?
Bond breaking where each bonding electron move to a different atom
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Heterolytic fission
Bonding breaking when both bonding electrons move to the same atom
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What are geometric isomers?
Molecules with the same structural formula but a different arrangement of atoms around a double bond.
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For something to form geometric isomers it must have...
1. C=C
2. Each C must be attached to 2 different groups
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Cis/trans?
If each carbon is bonded to at least one identical group to the other carbon = cis/trans

It is cis if they are on the same side (eg. both below the double bond)

It is trans is they are on opposite sides
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E/z?
Assigned based on priorities relative to Mr

e is opposite
z is same
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Suggest an explanation for trend in melting point of trans isomers
Trans isomers can stack more tightly therefore more energy is required to break it
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Suggest an explanation for trend in melting point of cis isomers
cis isomers have a higher boiling point than trans isomers because cis are polar and the electronegativity is dispersed
Also, cis isomers are more polar so have stronger PD interactions
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Alkene and Hydrogen
- Rm temp
- Platinum catalyst
makes an alkane
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Alkene and Hydrogen Bromide
- Rm Temp
makes major and minor bromoalkanes
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Alkene and Bromine
- Rm Temp
makes dibromoalkane
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Alkene and steam
- 570K, 65 atm, phosphoric acid catalyst absorbed on silica
makes an alcohol
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Alkene and acidified KMno4 and water
- Rm temp
makes a diol
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Alkene polymerisation
- 200 degrees
- catalyst
- pressure
makes a polymer
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Incineration (key points, advantages and disadvantages?)
- Burning plastics
- Produces steam to turn turbines --> electricity
- Air Pollution
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Land fill (key points, advantages and disadvantages?)
- burying and dumping in a designated area
- easy, cheap, keeps cities clean
- not biodegradable
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Recycling (key points, advantages and disadvantages?)
- Reusing materials
- uses less energy to make new plastics
- too much energy/expensive
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Feedstock for cracking (key points, advantages and disadvantages?)
- Using plastics in cracking process
- further use for plastic
- energy needed
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Other cards in this set

Card 2

Front

Explain how the boiling point of alkanes changes as the number of carbons increases

Back

As the no. of carbons increase, the boiling point increases due more london forces therefore more energy needed to overcome them.

Card 3

Front

Describe the temperature gradient in the fractionating column

Back

Preview of the front of card 3

Card 4

Front

What is a fraction?

Back

Preview of the front of card 4

Card 5

Front

State the property of the molecules in crude oil which allows the mixture to be separated into fractions

Back

Preview of the front of card 5
View more cards

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