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GCSE Chemistry > Topic 7 - Organic Chemistry > Flashcards

Topic 7 - Organic Chemistry Flashcards

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1
Q

What is a hydrocarbon?

A

A hydrocarbon is any molecule that is formed from carbon and hydrogen atoms only.

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2
Q

What are alkanes? What are they made up of? (2)

A
  • Simplest type of hydrocarbons.
  • Made up of chains of carbon atoms surrounded by hydrogen atoms.
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3
Q

What are the carbon bonds like in alkanes? (3)

A
  • No carbon-carbon double bonds.
  • So all the atoms have formed bonds with as many other atoms as they can.
  • This means they’re saturated.
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4
Q

What do different alkanes have?

A

Chains of different lengths.

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5
Q

What do the properties of alkanes depend on to change?

A

How long the carbon chain is.

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6
Q

What is the general formula of alkanes?

A

C(n)H(2n+2)

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7
Q

What are the three main trends in the properties of hydrocarbons?

A
  • The shorter the molecules, the more runny the hydrocarbon is => less viscous.
  • The shorter the molecules, the lower their boiling point is.
  • The shorter the molecules, the more flammable the hydrocarbon is.
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8
Q

What is the word equation for the complete combustion of hydrocarbons?

A

Hydrocarbon + Oxygen => Carbon Dioxide + Water Vapour

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9
Q

What does the process of complete combustion for hydrocarbons look like/how does it work? (4)

A
  • If you burn hydrocarbons, the carbon and hydrogen react with oxygen from the air to form carbon dioxide and water vapour.
  • The carbon and hydrogen are said to be oxidised.
  • Energy is released.
  • When there’s plenty of oxygen, all carbon atoms are completely oxidised => complete combustion.
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10
Q

What is crude oil?

A

A mixture of many different compounds. Most of the compounds in crude oil are hydrocarbon molecules, and the majority of them are alkanes.

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11
Q

How is crude oil formed? (3)

A
  • Formed from remains of plants and animals, mainly plankton, that died millions of years ago and were buried in mud.
  • Over millions of years, with high temperatures and pressures, the remains turn into crude oil.
  • This can be drilled up from the rocks where its found.
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12
Q

What process do you use to separate crude oil?

A

Crude oil can be split into separate groups of hydrocarbons using a technique called fractional distillation.

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13
Q

How does fractional distillation work? (Best to do this on a whiteboard) (6)

A
  • Crude oil is pumped into a fractionating column, which works continuously.
  • Fractionating column has a temperature gradient running through it - hottest at bottom, coldest at top.
  • Crude oil is first heated so it evaporates and is piped in at bottom of column.
  • Gas rises up the column and gradually cools.
  • Different compounds in mixture have different B.P, so condense at different temperatures => condense at different levels in the column.
  • The various fractions are constantly tapped off from the column at the different levels where they condense.
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14
Q

What are the groups of hydrocarbons that condense together called?

A

Fractions

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15
Q

What can fractions from crude oil be used for?

A

They can be processed to provide the fuel for most modern transport. Diesel oil, petrol, kerosene, heavy fuel oil and LPG are used to fuel cars, trains, planes and other forms of transport.

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16
Q

What are LPG’s characteristics? What is it used for? (4)

A
  • Lowest BP => gas at room temperature.
  • Ideal for using it as bottled gas.
  • Stored under pressure as liquid in ‘bottles’.
  • When the tap on the bottle is opened, fuel vaporises and flows to the burner where it’s ignited.
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17
Q

What is petrol’s characteristics? What is it used for? (3)

A
  • Higher BP => liquid at room temperature.
  • Ideal for storing in the fuel tank of a car.
  • Can flow to the engine where it’s easily vaporised to mix with the air before it is ignited.
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18
Q

What does the petrochemical industry use some of the hydrocarbons from crude oil for?

A

As a feedstock to make new compounds for use in things like polymers, solvents, lubricants, and detergents.

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19
Q

What are all the products you get from crude oil examples of?

A

Organic compounds => compounds containing carbon atoms.

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20
Q

Why do we get such a large variety of products from hydrocarbons? (3 bullet points)

A
  • Because carbon atoms can bond together to form different groups called homologous series.
  • These groups contain similar compounds that all have the same general formula and many properties in common.
  • Alkanes, alkenes, as well as other families such as alcohols and carboxylic acids, are all examples of different homologous series.
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21
Q

Why are shorter hydrocarbons more useful than longer ones? (2)

A
  • Short-chain hydrocarbons are flammable, so make good fuels and are in high demand.
  • Long-chain hydrocarbons form thick gloopy liquids like tar, which aren’t very useful.
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22
Q

What is cracking?

A

A process where a lot of the longer hydrocarbon molecules produced from fractional distillation are turned into smaller, more useful ones.

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23
Q

What are some of the products of cracking used for? (2)

A
  • Some of the products are useful as fuels, like petrol for cars and paraffin for jet fuel.
  • Other products, like ethene, are needed for making plastics.
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24
Q

What kind of reaction is cracking?

A

A thermal decomposition reaction => breaking molecules down by heating them.

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25
Q

What are the 2 methods that can be used to crack alkanes?

A
  • Catalytic Cracking
  • Steam Cracking
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26
Q

How does Catalytic Cracking work? (4)

A
  • Heat the long-chain hydrocarbons to vaporise them.
  • The vapour is then passed over a hot, powdered catalyst.
  • Aluminium oxide is one of the catalysts used.
  • The long-chain molecules split apart or ‘crack’ on the surface of the specks of catalyst.
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27
Q

How does Steam Cracking work? (3)

A
  • Heat the long-chain hydrocarbons to vaporise them.
  • The vapour can be mixed with steam and heated to a very high temperature.
  • Leads to thermal decomposition of long-chain hydrocarbon molecules to from smaller ones.
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28
Q

What are most of the products of cracking? (2)

A
  • Alkanes
  • Unsaturated hydrocarbons => Alkenes
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29
Q

What is an alkene?

A

Alkenes are a homologous series of hydrocarbons.

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30
Q

What are the characteristics of alkenes? (3)

A
  • More reactive than alkanes.
  • Have a double covalent bond between two of the carbon molecules in their chain.
  • Unsaturated - because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.
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31
Q

How do alkenes bond with other atoms? What does this mean in relation to alkanes?

A

The C=C double bond can open up to become a single bond, allowing the two carbon atoms to bond with other atoms. This makes alkenes more reactive than alkanes.

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32
Q

What are the first four alkenes?

A
  • Ethene => 2 carbon atoms
  • Propene => 3 carbon atoms
  • Butene => 4 carbon atoms
  • Pentene => 5 carbon atoms
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33
Q

What is the general formula of alkenes?

A

C(n)H(2n)

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34
Q

What does alkenes being reactive, make them useful for?

A

They are useful starting materials for making other organic compounds and polymers.

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35
Q

How can you distinguish between alkanes and alkenes? (3)

A
  • Using bromine water.
  • When orange bromine water is added to an alkane, no reaction will happen, and it’ll stay bright orange.
  • If it’s added to an alkene, a reaction occurs and the bromine water is decolourised - becomes clear.
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36
Q

What happens when you burn alkenes in air?

A

They tend to undergo incomplete combustion.

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37
Q

What is the word equation for the incomplete combustion of alkenes?

A

Alkene + Oxygen => Carbon + Carbon Monoxide + carbon Dioxide + Water

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38
Q

What does the incomplete combustion of alkenes look like? (3)

A
  • Results in a smoky yellow flame.
  • Less energy is being released compared to complete combustion of the same compound.
  • Type and amount of products depends on how much oxygen is present.
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39
Q

What is the C=C bond in alkenes an example of?

A

A functional group.

40
Q

What is a functional group?

A

A group of atoms that determines how a compound typically reacts.

41
Q

What does it mean that alkenes have a C=C functional group?

A

This means all alkenes react in similar ways, so you can suggest the products of a reaction based on your knowledge of how alkenes react in general.

42
Q

How do alkenes react most of the time? How does this work? (2)

A
  • By addition reactions.
  • The carbon-carbon double bond will open up to leave a carbon-carbon single bond, and a new atom is added to each carbon.
43
Q

What is the hydrogenation of alkenes? When does it take place? (2)

A
  • Hydrogen can react with the double-bonded carbons to open up the double bond and form the equivalent, saturated, alkane.
  • The reaction takes place between the alkene and hydrogen when in the presence of a catalyst.
44
Q

How do alcohols form from alkenes? (3)

A
  • When alkenes react with steam in the presence of a catalyst, water is added across the double bond and an alcohol is formed.
  • The -OH group can add to either of the carbons from the C=C bond. This can sometimes lead to more than one form of alcohol being produced.
  • The alcohol produced depends on the position of the C=C double bond in the chain.
45
Q

How do alkenes react with halogens in addition reactions? (2)

A
  • Alkenes will also react in addition reactions with halogens such as bromine, chlorine and iodine.
  • The molecules formed are saturated, with the C=C carbons each becoming bonded to a halogen atom.
46
Q

What is the most useful thing you can do with alkenes?

A

Addition polymerisation

47
Q

What is addition polymerisation?

A

When lots of small alkene molecules (monomers) open up their double bonds and join together to form very large molecules - these long-chain molecules are called polymers.

48
Q

What does addition polymerisation usually require? (2)

A
  • High pressure
  • A catalyst
49
Q

What are the products of addition polymerisation reactions?

A

Only the polymer => contains exactly the same type and number of atoms as the monomers that formed it.

50
Q

How can you recognise addition polymers?

A

By their repeating units, which always contain four groups arranged around a main chain containing 2 carbon atoms.

51
Q

Where does the name of the polymer come from?

A

Comes from the type of monomer its made from. E.g, propene becomes poly(propene).

52
Q

How can you draw the displayed formula of an addition polymer from the displayed formula of its monomer? (2)

A
  1. Start by drawing the 2 alkene carbons, replace the double bond with a single bond and add an extra single bond to each of the carbons.
  2. Fill in the rest of the groups in the same way that they surrounded the double bond in the monomer. Finally, stick a pair of brackets around the repeating part and put an ‘n’ after it.
53
Q

What is an alcohol?

A

The alcohols are a group of compounds that make up an homologous series all containing an -OH functional group (an oxygen atom covalently bonded to a hydrogen atom).

54
Q

What is the general formula of an alcohol?

A

C(n)H(2n+1)OH

55
Q

What is the basic naming system for alcohols?

A

The same as alkanes but you replace the final ‘e’ with an ‘ol’.

56
Q

What are the first four alcohols in the homologous series?

A
  • Methanol => CH(3)OH
  • Ethanol => C(2)H(5)OH
  • Propanol => C(3)H(7)OH
  • Butanol => C(4)H(9)OH
57
Q

What is the case for alcohols with more than one carbon atom in regards to chemical formulas? (2 bullet points)

A
  • There is more than one way to give the chemical formula.
  • You can just count up all the carbons and hydrogens and show them with the -OH group, or you can write the formula out showing the groups attached to each carbon atom separately.
58
Q

What 4 similar properties do the first four alcohols have?

A
  • Alcohols are flammable. They burn in air to produce carbon dioxide and water.
  • The first 4 all dissolve completely in water to form neutral solutions - don’t ionise like carboxylic acids do.
  • They react with sodium and one of the products of this is hydrogen.
  • They can be oxidised by reacting with oxygen to form carboxylic acids.
59
Q

How is alcohol used in alcoholic drinks?

A

Ethanol is the main alcohol in alcoholic drinks. It’s not as toxic as methanol (which causes blindness if drunk) but it still damages the liver and the brain.

60
Q

How is alcohol used generally in solvents? (3)

A
  • Alcohols such as methanol and ethanol can dissolve most compounds that water dissolves, but they can also dissolve substances that water can’t dissolve.
  • Things like hydrocarbons, oils and fats are insoluble in water, but they will dissolve in alcohols.
  • This makes ethanol, methanol, propanol and butanol very useful solvents in industry.
61
Q

How is ethanol used as a solvent?

A

Ethanol is the solvent for perfumes and aftershave lotions. It can mix with both the oils (which give the smell) and the water (that makes up the bulk).

62
Q

What is ‘Methylated spirit’ and what is it used for? (3)

A
  • ‘Methylated spirit’ or ‘meths’ is ethanol with chemicals (e.g, methanol) added to it.
  • It’s used to clean paint brushes and as a fuel (among other things).
  • It’s poisonous to drink, so a purply-blue dye is also added to stop people drinking it by mistake.
63
Q

How is ethanol used as a fuel? (3)

A
  • Ethanol is used as a fuel in spirit burners - burns fairly cleanly and it’s non-smelly.
  • Can also be mixed with petrol and used as fuel for cars.
  • Since ethanol is clean burning, the more ethanol in a petrol/ethanol mix, the less pollution is produced.
64
Q

What is fermentation in relation to ethanol?

A

The ethanol in beer, wine and other alcoholic drinks isn’t made from ethene it’s made from fermentation.

65
Q

What is the raw material for fermentation? What is it converted into? Using what?

A

The raw material for fermentation is sugar - it is converted into ethanol using enzymes found in yeast.

66
Q

What is the word equation for fermentation?

A

sugar —(yeast)—> carbon dioxide + ethanol

67
Q

Is fermentation carried out in solution, why?

A

The reaction is carried out in solution, so the ethanol that’s produced is aqueous.

68
Q

Under what conditions does fermentation happen best? (4)

A
  • fastest at a temperature of around 37 degrees C
  • in a slightly acidic solution
  • under anaerobic conditions (no oxygen)
  • yeast works best to convert sugar to alcohol in these conditions
69
Q

What would happens if the conditions for fermentation were different?

A

If they were different, e.g, a lower pH/ higher temperature or higher pH/ lower temperature, the enzyme could be denatured or could work at a much slower rate.

70
Q

What are carboxylic acids?

A

The carboxylic acids are a group of compounds that all contain a -COOH functional group. The -COOH group consists of a carbon atom that has formed a double bond with an oxygen atom and a single bond with an oxygen atom in an -OH group.

71
Q

What are the first 4 carboxylic acids in the homologous series?

A
  • Methanoic acid => HCOOH
  • Ethanoic acid => CH(3)COOH
  • Propanoic acid => C(2)H(5)COOH
  • Butanoic acid => C(3)H(7)COOH
72
Q

What is important when giving the chemical formula of a carboxylic acid?

A

It’s crucial that you show the -COOH group clearly. As a result, the chemical formulas of carboxylic acids are usually written out in full.

73
Q

What should you look for to see if something is a carboxylic acid? (2)

A
  • The -COOH group
  • ‘anoic acid’ at the end of its name
74
Q

What are 3 main properties of carboxylic acids?

A
  • They react like other acids. E.g, they react with carbonates to produce carbon dioxide, a salt and water. The salts formed end in ‘anoate’ => methanoic acid will form a methanoate.
  • They dissolve in water. When they do this, they can ionise and release H+ ions, which are responsible for making the solution acidic.
  • They only partially ionise in water and so are weak acids. As a result, carboxylic acids have a higher pH than aqueous solutions of strong acids (such as sulfuric acid) with the same concentration.
75
Q

What are esters? How are they formed? (2 bullet points)

A
  • Esters have the functional group ‘-COOC-‘.
  • They are formed from an alcohol and a carboxylic acid in the presence of a strong acid catalyst (e.g, concentrated sulfuric acid).
76
Q

What is the word equations for the formation of esters?

A

alcohol + carboxylic acid –(acid catalyst)—> ester + water

77
Q

What is condensation polymerisation and how does it work?

A

Condensation polymerisation involves monomers which contain two functional groups. When the monomers react together, bonds form between them, making polymer chains. For each new bond that forms, a small molecules (like water) is lost, hence the name condensation polymerisation.

78
Q

What do the simplest types of condensation polymers contain?

A

Two different monomers, each with two of the same functional groups.

79
Q

What can dicarboxylic acids react with to from ester links?

A

Dicarboxylic acids can react with diols to form ester links - this is a condensation reaction.

80
Q

How are polyesters formed? (3)

A
  • The molecule with the ester link - which is formed by dicarboxylic acids reacting with diols - has a functional group at each end.
  • These can also react in condensation reactions, making the chain longer.
  • The series of reactions together is known as condensation polymerisation and the resultant polymer is called a polyester.
81
Q

How is addition and condensation polymerisation different in regards to the number of types of monomer? (2)

A
  • In addition polymerisation, there is only one monomer type, an alkene, containing a C=C bond.
  • However, in condensation polymerisation, there are either two monomer types each containing two of the same functional group or one monomer type with two different functional groups.
82
Q

How is addition and condensation polymerisation different in regards to the number of products? (2)

A
  • Addition polymerisation reactions result in only one type of product being formed => the polymer.
  • In condensation polymerisation reactions, the polymer is formed but also a small molecule is formed. E.g, during the formation of a polyester, water is produced.
83
Q

How is addition and condensation polymerisation different in regards to the functional groups involved in polymerisation? (2)

A
  • In addition polymerisation the only functional group involved is the C=C double bond in the monomer.
  • This is different to condensation polymerisation which involves two reactive functional groups on each monomer.
84
Q

What does an amino acid contain?

A

An amino acid contains two different functional groups - a basic amino group (NH(2)) and an acidic carboxyl group (COOH).

85
Q

What can amino acids form? How? (3)

A
  • Amino acids can form polymers known as polypeptides via condensation polymerisation.
  • The amino group of an amino acid can react with the acid group of another, and so on, to form a polymer chain.
  • For every new bond that is formed, a molecule of water is lost.
86
Q

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

A

Proteins

87
Q

What are 4 important uses of proteins in the human body?

A
  • Enzymes work as catalysts speeding up reactions in the body.
  • Haemoglobin in red blood cells transport oxygen around the body.
  • Antibodies form part of the immune system. They find and get rid of things that could be harmful, such as viruses and bacteria.
  • The majority of body tissue is made from proteins.
88
Q

What gives proteins their different properties and shapes?

A

The order of the amino acids.

89
Q

What is DNA? (3)

A
  • DNA (deoxyribonucleic acid) is found in every living thing and many viruses.
  • It contains genetic instructions that allow the organism to develop and operate.
  • It’s a large molecule that takes a double helix structure.
90
Q

What is DNA made up of? What do these contain? (3)

A
  • DNA is made up of two polymer chains of monomers called ‘nucleotides’.
  • The nucleotides each contain a small molecule known as a base.
  • There are 4 different bases - A, C, G, T.
91
Q

How does the DNA get its double helix structure?

A

The bases on different polymer chains pair up with each other and form cross links, keeping the two strands of nucleotides together and giving the double helix structure.

92
Q

What does the order of the bases in DNA act as?

A

The order of the bases acts as a code for an organism’s genes.

93
Q

What are some examples of naturally occurring polymers? (2)

A
  • Proteins
  • Sugars => starch, cellulose
94
Q

What are sugars?

A

Sugars are small molecules that contain carbon, oxygen and hydrogen.

95
Q

What can sugars form when they react together?

A

Sugars can react together through polymerisation reactions to form polymers such as starch and cellulose.

96
Q

What is starch?

A

Starch is a polymer that’s used as a store of chemical energy in plants.

97
Q

What is cellulose?

A

Cellulose is a polymer that’s found in plant cell walls.

GCSE Chemistry (9 decks)

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