Topic 7: Organic Chemistry Flashcards

1
Q

What is a hydrocarbon?

A

Any compound that is formed from carbon and hydrogen atoms only

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2
Q

What is the general formula for alkanes?

A

CⁿH²ⁿ⁺²

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3
Q

Are alkanes saturated or unsaturated?

A

Saturated

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4
Q

Why are alkanes said to be saturated?

A

Each carbon atom forms 4 single covalent bonds

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5
Q

Do alkanes contain single or double bonds?

A

Single

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6
Q

What is a homologous series?

A

A group of organic compounds that react in a similar way

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7
Q

What are the first 4 alkanes?

A
  1. Methane
  2. Ethane
  3. Propane
  4. Butane
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8
Q

What is the trend as hydrocarbon chains get longer?
i) Viscosity
ii) Boiling point
iii) Flammability

A

i) Become more viscous (gloopy)
ii) Boiling point increases
iii) Become less flammable

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9
Q

What is the equation for the complete combustion of a hydrocarbon?

A

Hydrocarbon + oxygen —> carbon dioxide + water

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10
Q

During combustion, what happens to both carbon and hydrogen?

A

They are oxidised

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11
Q

Why are hydrocarbons used as fuels?

A

Due to the amount of energy they release when they combust completely

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12
Q

Describe how crude oil was formed [2]

A
  1. Formed from the remains of plants and animals, mainly plankton, that died millions of years ago and were buried in mud
  2. Over millions of years, with high temperatures and pressures, the remains turned to crude oil
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13
Q

Why is crude oil described as a non-renewable fuel?

A

It is being used up much faster than it is being formed

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14
Q

Why is crude oil described as a finite resource?

A

One day it will run out

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15
Q

What is crude oil made up of?

A

A mixture of lots of different hydrocarbons, most of which are alkanes

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16
Q

How are the different compounds in crude oil separated?

A

Fractional distillation

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17
Q

Describe how different compounds in crude oil are separated by fractional distillation [7]

A
  1. Oil is heated until it has turned into a gas
  2. The gas is fed into a fractionating column
  3. In the column there is a temperature gradient (it’s hot at the bottom and gets cooler as you go up)
  4. The longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column early on, when they’re near the bottom
  5. The shorter hydrocarbons have lower boiling points. They condense and drain out much later on, near the top of the column where it’s cooler
  6. You end up with a crude oil mixture separated out into different fractions
  7. Each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points
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18
Q

What are the long hydrocarbons in fractional distillation used for?

A

Heavy fuel oil

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19
Q

What can heavy fuel oil be? [3]

A
  1. Heating oil
  2. Fuel oil
  3. Lubricating oil
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20
Q

What are the medium hydrocarbons in fractional distillation used for? [3]

A
  1. Diesel
  2. Kerosene
  3. Petrol
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21
Q

What are the short hydrocarbons in fractional distillation used for?

A

LPG (liquefied petroleum gas)

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22
Q

What does the petrochemical industry use hydrocarbons for?

A

Feedstock

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23
Q

Why are long-chain hydrocarbons not very useful?

A

They form thick, gloopy liquids which cannot be used as fuels

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24
Q

In what process are long-chain hydrocarbons made into short-chain hydrocarbons?

A

Cracking

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25
Q

In cracking, what other hydrocarbon is produced?

A

Alkenes

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26
Q

What kind of reaction is cracking?

A

A thermal decomposition reaction

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27
Q

Define ‘thermal decomposition’

A

Breaking molecules down using heat

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28
Q

What are the 2 types of cracking?

A
  1. Catalytic cracking
  2. Steam cracking
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29
Q

Describe the process of catalytic cracking [3]

A
  1. Heat the long-chain hydrocarbons to vaporise them
  2. Pass the vapour over hot powdered aluminium oxide catalyst
  3. The long-chain molecules split apart on the surface of the specks of catalyst
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30
Q

Describe the process of steam cracking [3]

A
  1. Heat the long-chain hydrocarbons to vaporise them
  2. Mix them with steam
  3. Heat them at very high temperatures
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31
Q

When writing an equation for cracking, what is it important to do?

A

Balance the number of carbon and hydrogen atoms on both sides

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32
Q

What kind of bond does an alkene have?

A

C=C double bond

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33
Q

Why are alkenes said to be unsaturated?

A

The C=C double bond means that alkenes have two fewer hydrogens compared with alkanes containing the same number of carbon atoms

34
Q

Why are alkenes much more reactive than alkanes?

A

The C=C double bond can open up to make a single bond, allowing the 2 carbon atoms to bond with other atoms

35
Q

What are the first 4 alkenes?

A
  1. Ethene
  2. Propene
  3. Butene
  4. Pentene
36
Q

What is the general formula for alkenes?

A

CⁿH²ⁿ

37
Q

What is the test to distinguish between alkenes and alkanes?

A

Bromine water test

38
Q

What will happen to bromine water in the presence of an alkene?

A

The solution will lose its orange colour and turn colourless

39
Q

What will happen to bromine water in the presence of an alkane?

A

The solution will stay orange

40
Q

What are the 3 types of addition reactions that alkenes can carry out?

A
  1. Addition of hydrogen
  2. Addition of steam
  3. Addition of a halogen
41
Q

Describe what happens in a hydrogenation reaction [2]

A
  1. Hydrogen is reacted with an alkene (C=C double bond)
  2. The C=C double bond is opened up and the equivalent, saturated alkane is formed
42
Q

What has to be present in a hydrogenation reaction?

A

A catalyst

43
Q

What happens when alkenes react with steam?

A

Water is added across the double bond and an alcohol is formed

44
Q

How can ethanol (an alcohol) be made?

A

By mixing steam and ethene and passing it over a catalyst

45
Q

Describe how you would isolate pure alcohol from ethanol, ethene and water [4]

A
  1. Ethanol, ethene and water is present
  2. The reaction mixture is passed from the reactor into a condenser
  3. Ethanol and water have a higher boiling point than ethene, so both condense leaving the unreacted ethene
  4. Ethanol and water is then separated by fractional distillation
46
Q

What is a polymer?

A

Large molecule formed when lots of monomers join together

47
Q

In polymerisation, what two conditions are needed? [2]

A
  1. High pressure
  2. Catalyst
48
Q

What would be the name for an ethene polymer be?

A

poly(ethene)

49
Q

What is the general formula for alcohols?

A

CⁿH²ⁿ⁺¹OH

50
Q

What is the functional group for alcohols?

A

-OH

51
Q

Name the first 4 alcohols

A
  1. Methanol
  2. Ethanol
  3. Propanol
  4. Butanol
52
Q

What are the properties of alcohols
i) Flammability
ii) Solubility

A

i) Highly flammable (undergo complete combustion)
ii) Soluble in water - neutral pH

53
Q

What happens when alcohols are oxidised?

A

Produce carboxylic acid

54
Q

What are alcohols used for? [2]

A
  1. Solvents in industry
  2. Fuels
55
Q

Why are alchols used as solvents in industry?

A

Because they can dissolve substances that water can’t disslolve e.g. oils and fats

56
Q

What time of burner is ethanol (alcohol) used as fuel in?

A

Spirit burner

57
Q

Positives of spirit burners [2]

A
  1. Burns fairly cleanly
  2. Non-smelly
58
Q

What are the 3 main uses of ethanol?

A
  1. As a chemical feedstock
  2. As a biofuel
  3. Used in alcoholic drinks
59
Q

Advantages of producing ethanol from ethene and steam

A

The reaction is cheap and efficient

60
Q

Disadvantages of producing ethanol from ethene and steam

A

Ethene is made from crude oil, which is non-renewable (could become expensive)

61
Q

Advantages of producing ethanol from fermentation

A

Glucose used is renewable - won’t run out

62
Q

Disadvantages of producing ethanol from fermentation

A

Process can be slow

63
Q

Fermentation equation

A

Glucose —> ethanol + carbon dioxide

64
Q

What is the functional group for carboxylic acid?

A

-COOH

65
Q

What is produced when a carboxylic acid reacts with a carbonate?

A

Salt + water + carbon dioxide

66
Q

THINK: alcohols

What is the general formula for carboxylic acids?

A

CⁿH²ⁿ⁺¹COOH

67
Q

What is the functional group of an ester?

A

-COO-

68
Q

What are esters formed from?

A

An alcohol and a carboxylic acid

69
Q

What type of catalyst has to be used to produce an ester?

A

Acid catalyst

70
Q

What is produced as a by-product when an ester is formed?

A

Water

71
Q

What is ethyl ethanoate (ester) made from?

A

Ethanoic acid and ethanol

72
Q

What are esters used in? [2]

A
  1. Perfumes
  2. Food colourings
73
Q

Why is it called condensation polymerisation?

A

For each new bond that forms, a small molecule (water) is lost

74
Q

Why are condensation polymers biodegradable?

A

Ester links can be broken down by microorganisms

75
Q

What are the 3 naturally occurring polymers?

A
  1. Amino acids
  2. DNA
  3. Carbohydrates
76
Q

What are the 2 functional groups of an amino acid?

A
  1. Amino group
  2. Carboxyl group
77
Q

What is the name for the polymers that amino acids form?

A

Polypeptides

78
Q

What is one or more long-chains of polypeptides known as?

A

Proteins

79
Q

What are the two polymer chains in DNA called?

A

Nucleotides

80
Q

What small molecules are sugars made from? [3]

A
  1. Carbon
  2. Oxygen
  3. Hydrogen
81
Q

What long-chain polymers can sugars form?

A

Starch