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Organic chemistry Flashcards

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1
Q

What is meant by crude oil?

A

A finite resource found in rocks made up of a mixture of hydrocarbons.

This is why we can separate it via fractional distillation.

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2
Q

What is crude oil made from?

A

The remains of ancient biomass consisting of mainly plankton, compressed and buried in mud over a period of millions of years.

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3
Q

True or false, crude oil is a fossil fuel?

A

True.

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4
Q

What molecule does crude oil mainly consist of?

A

Hydrocarbons.

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5
Q

What is meant by a hydrocarbon?

A

A molecule consisting of only hydrogen and carbon atoms.

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6
Q

What is meant by ‘alkanes’?

What is the general formula for alkanes?

A

A homologous series of saturated hydrocarbons consisting of only single C-C covalent bonds.

CnH2n+2

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7
Q

What is meant by a homologous series?

A

A sequence of compounds with the same functional group and similar chemical properties.

A functional group = a group of atoms in a molecule that are responsible for how that molecule reacts.

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8
Q

What are the first 4 alkanes?

A
  • Methane (CH4)
  • Ethane (C2H6)
  • Propane (C3H8)
  • Butane (C4H10)

^^These are all gases at room temp. because they have boiling points lower than room temp.

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9
Q

Why are alkanes considered saturated?

A

Because they consist of only single covalent bonds where the C atoms are fully bonded to the H atoms.

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10
Q

Describe the properties of hydrocarbons in terms of:

  • Boiling point (the temp a liquid turns into a gas)
  • Viscosity (the thickness of a fluid and how easily it flows)
  • Flammability (how easily a molecule combusts)

And how this relates to their size.

A

VISCOSITY: As the size of the HC molecule chain length increases, the viscosity increases.

FLAMMABILITY: As the size of the HC molecule chain length increases the flammability decreases.

BOILING POINT: As the size of the HC molecule chain length increases the boiling point increases (more and stronger IMFA so more energy is required to break the bonds).

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11
Q

During the combustion of Hydrocarbons what is released?

A

Energy.

The combustion of HC releases energy so HC can be used as fuels.

During the combustion of HC Hydrogen and Oxygen atoms react with oxygen in the air to become oxidised.

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12
Q

Complete combustion:

  • Define
  • What are the products?
A

An exothermic reaction that occurs when there is an unlimited supply of oxygen.

During complete combustion Carbon dioxide + Water are produced.

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13
Q

Under what conditions does Incomplete combustion occur?

A

When there is a limited supply of oxygen in the air.

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13
Q

General equation for complete combustion of an alkane:

A

Hydrocarbon + O2 -> Carbon Dioxide + Water

^^The products of complete combustion are always CO2 and H2O

*You should be able to balance equations of complete and incomplete combustion.

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14
Q

What are always the products of incomplete combustion?

A

Carbon Monoxide (CO) and Water

OR

Carbon (C) aka Soot and Water

Hydrocarbon + Oxygen -> CO/C + H2O

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15
Q

Explain why incomplete combustion is dangerous:

A

Incomplete combustion produces CO, CO is a toxic gas that is.

  • Odourless
  • Colourless
  • Poisonous
  • Tasteless

It binds to haemoglobin on RBC reducing the oxygen transfer around the body.

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16
Q

What does fractional distillation of crude oil involve?

A
  • Separating hydrocarbons in crude oil into fractions that each contain molecules with a similar number of carbon atoms.
  • This allows for HC of different chain lengths to become useful.
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17
Q

Describe the process of fractional distillation of crude oil:

A
  • Crude oil is heated to vaporise and fed into the fractionating column where the temperature is hotter towards the bottom of the fractionating column and cooler towards the top.
  • The crude oil vapour rises rapidly and HC of different chain lengths condense at their boiling points.
  • Longer HC chain lengths condense towards the bottom of the FC there it is hotter and shorter HC chain lengths remain gases or condense towards the top of the FC where it is cooler.
  • At each boiling point temp. a fraction is produced containing HC of similar chain lengths.
  • Fractional distillation occurs as a continuous process.
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18
Q

What are fractions produced from fractional distillation used for?

A

The fractions can be processed to produce fuels and feedstock for the petrochemical industry.

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19
Q

What is meant by feedstock?

A

A raw material used to provide reactants for an industrial reaction.

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20
Q

What are the 5 fuels produced from fractional distillation?

A
  • Petrol
  • Diesel oil
  • Kerosene
  • Heavy fuel oil
  • Liquified petroleum gases (LPG) (V short chain HC eg propane and butane)
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21
Q

What useful materials are produced in every day life from the fractions by the petrochemical industry?

A
  • Solvents
  • Lubricants
  • Detergents
  • Polymers
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22
Q

True or false, long chain hydrocarbons are not useful as fuels as they aren’t flammable, and due to the high demand of shorter chain HC there aren’t enough so we have to break the longer ones down?

A

True, this is called cracking.

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23
Q

Cracking:

A

The breaking down of longer chain hydrocarbon molecules to produce smaller and more useful molecules.

^The longer ones are broken down bc they aren’t as useful, and now the shorter ones can be used as fuels.

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24
Q

What are the products of cracking?

A
  • Shorter chain alkanes
  • Alkenes
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25
Q

What are the two types of cracking?

A
  • Steam cracking
  • Catalytic cracking
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26
Q

Why are alkenes produced by cracking useful?

A

They can be used as:

  • Polymers
  • Starting materials for other useful chemicals
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27
Q

What occurs during steam cracking?

A

CONDITIONS:

  • High temperature
  • Steam

The longer HC chains are mixed with steam and heated to high temperatures to allow thermal decomposition to occur for them to be broken down into smaller and more useful alkanes and alkenes.

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28
Q

What occurs during catalytic cracking?

A

CONDITIONS
- High temperature
- Catalyst

The longer hydrocarbon chains are passed over a hot catalyst and thermal decomposition occurs. The catalyst speeds up the rate of this reaction.

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29
Q

True or false, alkenes are more reactive than alkanes?

A

True. (Bc they are unsaturated and have a double C-C covalent bond)

This is why we can test for alkenes using the bromine water test.

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30
Q

Describe the test for alkenes:

A
  • Bromine water test.
  • If alkenes are present, orange bromine water is decolourised.

DON’T SAY CLEAR!

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31
Q

Balancing cracking equations:

A
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32
Q

What are alkenes?

A

A homologous series of unsaturated hydrocarbons consisting of double C=C covalent bonds.

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33
Q

State why alkenes are unsaturated

A

They have 2 fewer hydrogen atoms than the alkane with the same number of carbon atoms.

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34
Q

What is the functional group for alkenes?

A

C=C

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35
Q

What is the general formula for alkenes?

A

CnH2n

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36
Q

Why are alkenes not used as fuels?

A
  • The don’t burn cleanly with oxygen - they produce smokey flames.
  • A lot of energy is required to break their double C=C covalent bond.
  • So combustion of alkenes is incomplete which produced C or CO
  • This is dangerous (CO binds to haemoglobin in RBC preventing transfer of O2 around the body).
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37
Q

Alkenes we need to know for GCSE:

A
  • Ethene (C2H4)
  • Propene (C3H6)
  • Butene (C4H8)
  • Pentene (C5H10)
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38
Q

Draw the 4 Alkenes (Ethene - Pentene)

A
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39
Q

What are the four reactions of Alkenes you must know?

A
  • Halogenation of alkenes (w halogens)
  • Hydrogenation of alkenes (w hydrogen)
  • Combustion of alkenes (w oxygen)
  • Hydration of alkenes (w water)
40
Q

Combustion of alkenes:

  • Products
  • Conditions
A

Alkenes combust (react with oxygen) to produce:

  • CO2 and H2O in complete combustion
  • CO/C and O2 in incomplete combustion

The conditions for:
- complete combustion - unlimited supply of O2
- incomplete combustion - limited supply of O2

^A smoky flame is produced.
^Alkenes don’t combust completely.

why may alkenes undergo incomplete combustion?
- The are unsaturated so have a double C-C covalent bond that needs to be broken.
- This requires a lot of energy in the form of O2
- So during combustion of alkenes O2 is rapidly used up to break the IMFA and the C=C covalent bonds

41
Q

Hydrogenation of Alkenes (alkenes reacting with only hydrogen):

  • Conditions
  • Product
  • What happens?
A

Conditions:
- High temperatures
- Nickel catalyst to speed up reaction

Product:
- Alkane (w the same no. of carbon atoms)

eg Pentene + Water -> Pentane

What happens?

^During hydrogenation of alkenes the double C-C is converted into a single one.
^The 2 hydrogen atoms are added across the double bond.
^To produce an alkane.

42
Q

Hydration of alkenes (Alkenes reacting with only water)

ALKENE + WATER ->< ALCOHOL of the same alkene

A

Conditions
- High temperatures
- High pressures
- Phosphoric acid catalyst

Products:
- Alcohol

What happens?
^When alkenes react with water, the double C=C covalent bond is converted into a single one.
^The H2O molecule splits into two groups, OH and H, and each group attaches to either side of now unsaturated HC molecule to produce an alcohol.

So what is produced when ethene reacts with water? ETHANOL

43
Q

True or false, the reaction of alkenes and water is a reversible reaction?

A

True.

44
Q

Ethene reacts with water to produce ethanol in a reversible reaction.

Ethanol is produced in a mixture of unreacted ethene and water.

Ethanol is a useful substance.

What can we do to increase the yield of ethanol?

A

1- pass unreacted ethene through the phosphoric acid catalyst.

2- Cool the mixture of ethanol, unreacted ethene and water.
- Because ethanol has a low BP it won’t condense and will remain as a gas but the water and ethanol will.
- Use fractional distillation to separate the ethanol from the water and bc ethanol has a lower bp than water it will boil first and be separated.

45
Q

Halogenation of Alkenes (Alkene reacting with halogens)

  • Conditions
  • Products
  • What happens?
A

Conditions: NONE

Products: di-halo-alkane

EG:
Ethene + Bromine -> Dibromoethane
Pentene + Chlorine -> Dichloropentane

etc

What happens?
- The double C=C covalent bond is broken and each halogen atom attaches itself across the double bond to produce a di-halo-alkane.

46
Q

Why does bromine water become colourless when it reacts with ethene?

A

It is completely used up.

^That’s why we test for alkenes using bromine water.

47
Q

What are alcohols?

A

A homologous series with the functional group with the functional group -OH.

Alcohols are NOT hydrocarbons.

48
Q

The functional group of alcohols?

A

CnH2n+1OH

49
Q

What are the 4 alcohols we have to know?

A
  • Methanol (CH3OH)
  • Ethanol (C2H2OH)
  • Propanol (C3H7OH)
  • Butanol (C4H9OH)
50
Q

How can alcohol also be represented?

A

By their structural formulae (breaking the displayed formulae down, check notes)

51
Q

What can alcohols be used for?

A

As fuels

52
Q

What can methanol be used for? x3

A
  • Chemical feedstock
  • Antifreeze
  • Biodiesel
53
Q

What can ethanol be used for? x2

A
  • Solvents
  • Alcoholic drinks
54
Q

State and describe the two ways at which ethanol can be produced:

A
  • By reacting ethene and water.
  • Fermentation of sugar (glucose)
55
Q

Advantages and disadvantages of producing ethanol by reacting ethene and water?

A
  • AD: It produces a high yield of ethanol
  • DISAD: Requires high temperatures and so a lot of energy.
  • DISAD: Ethene used to produce it is non-renewable - comes from crude oil.
56
Q

How can we make ethanol by fermentation?

A

Glucose solution is mixed with a yeast catalyst which converts the glucose solution into ethanol solution.

Conditions:
- Low temperatures
- Anaerobic conditions (lack of O2)
- Yeast catalyst

57
Q

What are the advantages and disadvantages of producing ethanol by fermentation?

A

AD - Glucose is renewable as it comes from plants, unlike ethene.
AD - Requires low energy due to low temperatures.

DISAD - Ethanol is dissolved in H2O, the solution of ethanol produced is aqueous so needs to be purified via fractional distillation which requires energy.

58
Q

What are the four reactions of alcohol we need to know?

  • Alcohols and water
  • Alcohols and sodium
  • Alcohols and oxidising agents
  • Alcohols and oxygen (combustion)
A
  • Alcohols and water
  • Alcohols and sodium
  • Alcohols and oxidising agents
  • Alcohols and oxygen (combustion)
59
Q

Alcohols and oxidising agents:

A

Alcohol oxidising agent —> Carboxylic acid + water

(the oxidising agent goes on top of the arrow)

Eg ethanol -> oxidising agent -> Ethanoic acid + water

60
Q

What is meant by an oxidising agent?

A

A chemical substance that oxidises other substances.

61
Q

What is an example of an oxidising agent?

A

Acidified potassium dichromate.

62
Q

Alcohols in water
- What happens
- What is produced

A

Alcohols are soluble in water, they dissolve neutral solutions with a pH of 7.

63
Q

Describe solubility of alcohols with regards to their chain lengths

A

As the chain length of the alcohol increases the solubility decreases

64
Q

Alcohols and sodium reaction:

A

Alcohol + Sodium -> Sodium + Hydrogen

Eg sodium and ethanol will produce sodium ethoxide and hydrogen

65
Q

What are carboxylic acids?

A

A homologous series of weak acids with the functional group -COOH

66
Q

Why are carboxylic acids considered weak acids?

A
  • They only partially ionise in aqueous solutions so their H+ ions don’t completely dissociate.

Because they are weak acids they have a higher pH than strong acids with the same concentration.

67
Q

Draw and state the first 4 carboxylic acids.

A
  • Methanoic acid
  • Ethanoic acid y
  • Propanoic acid
  • Butanoic aci
68
Q

Reactions of carboxylic acids that we must know

A
  • Carboxylic acids and water
  • Carboxylic acids and metal carbonates
  • Carboxylic acids and alcohols
69
Q

Carboxylic acids and water:

A
  • Carboxylic acids dissolve in water to form a;

Carboxylate ion
Hydrogen ion

**remember because they are weak acids it is a reversible reaction

70
Q

Carboxylic acids react with metal carbonates to produce:

A
  • A salt (aq)
  • CO2 (g)
  • H2O (l)

Eg propanoic acid + potsssium carbonate -> potassium propanoate + carbon dioxide + water

71
Q

Carboxylic acid and alcohols

  • What are the products
  • What are the conditions
A

They react to produce an ester and water.

Eg Ethanoic acid + Ethanol -> ethyl ethanoate + water

USING A SULFURIC ACID CATALYST

Conditions: sulfuric acid catalyst

72
Q

Why are esters useful?

A

Their sweet pleasant smell means they can be used in foods and perfumes

73
Q

What is a polymer?

A

A large long-chain molecule consisting of many small monomers covalent bonded together

74
Q

What are the two types of polymers we need to know?

A
  • Addition polymers
  • Condensation polymers
75
Q

In addition polymers what are the monomers?

A

Alkenes

76
Q

Information about addition polymerisation;

A
  • In AP the monomers are alkenes
  • The name of the polymer
    produced is called poly(alkene) eg a polymer made up of ethene monomers will be called poly(ethene)
  • In AP the monomers have a double C-C covalent bond but the polymers only consist of single C-C covalent bonds.
77
Q

What is the short hand method scientists can use to write polymers instead of their long chains?

A

Repeating units.

Take to carbon pieces from the monomer and stick it in brackets w two sticks sticking out.

Write an n on the right, the n represents a large number

NOTE
- In addition polymerisation the repeating unit has the same number of atoms as the monomer and this is because no other molecules are formed in the reaction, monomers are only joined together.
- The repeating unit doesn’t contain a double bond.

78
Q

Condensation polymerisation notes

A
  • It involves monomers with the same fg.
  • Two functional groups reacting together to produce a polyester and a small molecule such as water (2H2O)
  • DRAW for a dicarboxylic acid and diol spot the ester link (FG for an ester).
79
Q

True or false polyesters are biodegradable?

A
  • Bacteria and microorganisms can break down the ester links, unlike addition polymerisation.
80
Q

Differences between addition polymerisation and condensation polymerisation;

A
  • Addition polymerisation requires just one starting monomers but condensation polymerisation requires a minimum of two different starting monomers.
  • Only one product is formed from addition polymerisation but a small molecule is given off from CP
  • Addition polymers are non-biodegradable but condensation polymers are biodegradable
81
Q

Draw glycine’s displayed formula
What is its structural formula?

A
82
Q

True or false glycine monomers have two functional groups.

A

True

  • Carboxylic acid group (COOH)
  • Amine group (NH2)

This allows for it to undergo condensation polymerisation

83
Q

Give an example of an amino acid

A

Glycine

84
Q

When glycine undergoes condensation polymerisation what molecules are lost

A

Water molecules.

  • Carboxylic acid group loses a hydroxide molecule (OH)
  • Amine group loses a Hydrogen molecule (H)

These combine to produce a water molecule

85
Q

What is a polypeptide?

A

A protein made up of just one type of amino acid

86
Q

A protein is

A

A molecule made up of different amino acids

87
Q

Short hand way of writing the condensation polymerisation of glycine DRAW IT:

A
88
Q

What is meant by DNA?

A

A large molecule that is essential for life.

89
Q

What does DNA do?

A

DNA encodes genetic instructions for the development and the functioning of living organisms and viruses.

90
Q

What monomers is DNA made up of?

A

Nucleotides.

91
Q

Describe the structure of DNA:

A

DNA is made up of two polymer chains which are made up of monomers called nucleotides.

The polymer chains wrap around each other to form a structure called a ‘double helix’.

92
Q

What are the monomers in DNA (nucleotides)

A

A, C, T and G

93
Q

DNA is a polymer of?

A

Nucleotides

94
Q

Proteins are polymer of?

A

Amino acids

95
Q

Starch is a polymer of?

A

Glucose

96
Q

Cellulose is a polymer of?

A

Glucose

97
Q

Describe the arrangement of glucose monomers in starch and cellulose.

A

They are arranged in different ways.

GCSE Chemistry (13 decks)

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