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Organic Chemistry Flashcards

1
Q

What are hydrocarbons?

A

Molecules made up of hydrogen and carbon atoms ONLY.

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2
Q

What is the general formula for the homologous series of alkanes?

A

Cn H2n+2

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3
Q

Meth

A

One carbon

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4
Q

Eth

A

Two carbons

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5
Q

Prop

A

Three carbons

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6
Q

But

A

Four carbons

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7
Q

Pent

A

Five carbons

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8
Q

What ending signifies an alkane molecule?

A

ane

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9
Q

What are the first four members of the alkanes?

A

-methane
-ethane
-propane
-butane

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10
Q

How can alkanes be represented?

A

Using formulae e.g. C₂H₆

or using a displayed formula.

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11
Q

What do some properties of hydrocarbons depend on?

A

The size of their molecules.

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12
Q

What does the properties of different hydrocarbons influence?

A

How the hydrocarbons are used as fuels.

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13
Q

How does boiling point change with increasing molecular size and why?

A

The larger the molecules the higher the boiling point because the intermolecular forces between molecules are stronger and so require more energy to overcome.

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14
Q

How does viscosity change with increasing molecular size?

A

The larger the molecules the more viscous the hydrocarbon (i.e. the more gloopy/less runny).

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15
Q

How does flammability change with decreasing molecular size?

A

The smaller the molecules, the more flammable the hydrocarbon is (i.e. its easier to ignite).

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16
Q

Hydrocarbons with large molecules are often referred to as what?

A

Long-chain hydrocarbons

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17
Q

Hydrocarbons with small molecules are often referred to as what?

A

Short-chain hydrocarbons

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18
Q

What type of fuels are short-chain hydrocarbons often used as?

A

‘Bottled gases’.

Because they have lower boiling points they can be stored under pressure as gases in bottles.

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19
Q

What is a homologous series?

A

A group of organic compounds that have similar chemical properties, due to them having the same general formula/functional group.

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20
Q

Isomers

A

Molecules made of the same atoms but are arranged in different ways.

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21
Q

What are alkanes?

A

The simplest type of hydrocarbon where each carbon atom forms FOUR SINGLE covalent bonds.

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22
Q

Saturated compound (for understanding)

A

One which contains the maximum possible number of hydrogen atoms bonded to its carbon atoms, with no carbon-carbon double or triple bonds present.

basically only single bonds present!

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23
Q

What is crude oil?

A

Crude oil is a finite resource found in rocks.

It is a mixture of a very large number of compounds.

Most of the compounds in crude oil are hydrocarbons, most of which are alkanes.

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24
Q

How is crude oil formed?

A

Crude oil is formed from the remains of an ancient biomass consisting mainly of plankton that was buried in mud.

Over millions of years - with high temperature and pressure - the remains turn to crude oil (which can be drilled up from the rocks where it’s found).

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25
Q

How is crude oil separated into fractions?

A

Fractional Distillation

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26
Q

Describe and explain how crude oil is separated into fractions by fractional distillation.

A

Crude oil is heated to vaporise the hydrocarbons and they are fed into the bottom of a fractionating column.

The temperature of the column decreases from bottom to top so the fractions condense at different heights.

This is because they have different boiling points.

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27
Q

What are fractions? (chemistry)

A

Groups of hydrocarbons with a similar number of carbon atoms and therefore similar melting and boiling points.

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28
Q

What can fractions be processed to produce?

A

Fuels (e.g. for transport) and feedstock for the petrochemical industry.

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29
Q

Give examples of fuels we depend on for our modern lifestyle (highest to lowest boiling point = bottom to top of fractionating column).

A

heavy fuel oil, diesel oil, kerosene, petrol/gasoline, liquefied petroleum gases (LPG)

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30
Q

What is gasoline/petrol used for?

A

Fuel in car engines

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31
Q

What is kerosene used for?

A

Aircraft fuel

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32
Q

Feedstock

A

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

(these reactions make new compounds for use in things such as polymers, solvents, lubricants, and detergents.)

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33
Q

Why is there such a vast array of natural and synthetic carbon compounds?

A

Due to the ability of carbon atoms to form families of similar compounds. (homologous series)

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34
Q

Petrochemical

A

A substance made from crude oil, via chemical reactions.

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35
Q

Feedstocks vs petrochemicals

A

The different hydrocarbons in crude oil are feedstocks and the things we make from them (polymers, lubricants, etc.) are petrochemicals.

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36
Q

What does the combustion of hydrocarbon fuels release?

A

Energy

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37
Q

What happens to carbon and hydrogen in the (hydrocarbon) fuels during combustion?

A

They are oxidised because they gain oxygen.

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38
Q

What are the products of the complete combustion of a hydrocarbon?

A

Carbon Dioxide + Water

(Water is in the gaseous form, aka water vapour).

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39
Q

Students should be able to write balanced equations for the complete combustion of hydrocarbons…

A

…with a given formula.

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40
Q

Complete combustion

A

Oxygen burns fully (as there’s an unlimited supply).

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41
Q

How do we test for carbon dioxide (product of complete combustion)?

A

Bubble the CO₂ gas through limewater.

For a positive result, the limewater turns cloudy.

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42
Q

How do we test for water (product of complete combustion)?

A

Add anhydrous copper sulfate powder.

For a positive result, the crystals will go from white to blue as the anhydrous copper sulfate goes to hydrated copper sulfate. (CuSO₄·5H₂O)

Alternatively use anhydrous cobalt chloride (blue to pink when hydrated).

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43
Q

When does incomplete combustion occur?

A

When there’s a limited supply of oxygen.

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44
Q

What are the products of incomplete combustion?

A

Carbon monoxide + Carbon + H₂O

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45
Q

Why is incomplete combustion bad?

A

-Not much energy is given out

-Carbon monoxide is a toxic gas: it binds to haemoglobin instead of oxygen leading to unconsciousness and death

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46
Q

Are longer or shorter hydrocarbons more useful? Why?

A

Short- chain hydrocarbons have lower boiling points so are more flammable and therefore make better fuels. They are in high demand.

Long-chain hydrocarbons are more viscous, forming thick gloopy liquids like tar which aren’t as useful.

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47
Q

Why are hydrocarbons used as fuels?

A

A large amount of energy is released when they combust completely.

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48
Q

Which reactants are oxidised (gain oxygen) during complete combustion?

A

Both hydrogen and carbon from the hydrocarbon.

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49
Q

What is cracking?

A

The breaking down of long-chain hydrocarbons into smaller ones.

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50
Q

What are the products of cracking?

A

A smaller alkane and an alkene.

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51
Q

What are some of the products of cracking useful as?

A

Fuels e.g. petrol for cars and kerosene for planes.

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52
Q

What type of reaction is cracking?

A

It is a type of thermal decomposition because molecules are broken down by heating them.

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53
Q

Hydrocarbons can be broken down (________) to produce _______, more _______ molecules

A

cracked
smaller
useful

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54
Q

Explain why compounds with the highest boiling points are found at the bottom of the fractionating column.

A

They have the longest molecules and therefore the strongest intermolecular forces.

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55
Q

Why is cracking needed?

A

To meet the high demand for more short-chain hydrocarbons such as petrol, which are useful as fuels.

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56
Q

Describe the conditions used for catalytic cracking.

A

-High temperatures
-A catalyst

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57
Q

Describe the conditions used for steam cracking.

A

-High temperatures
-Steam.

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58
Q

How can cracking be done?

A

By various methods including catalytic cracking and steam cracking.

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59
Q

Are alkanes or alkenes more reactive?

A

Alkenes, hence they react with bromine water.

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60
Q

What is the test for an alkene?

A

Bromine water is used to test for an alkene product.

For a positive result, the solution will go from orange to colourless.

61
Q

What is the colour change when bromine water reacts with an alkene?

A

Orange to Colourless (if the hydrocarbon is indeed unsaturated).

62
Q

Saturated

A

Contains only single bonds.

63
Q

Unsaturated

A

Can contain (Carbon-Carbon) double bonds.

64
Q

Practice some…

A

cracking equations!!!

64
Q

Explain how modern life depends on the uses of hydrocarbons.

A

Petrol is an example of an alkane in high demand in modern life for its use as a fuel in car engines.

Liquefied petroleum gas (LPG) is another example of a hydrocarbon and can be used as fuel for commercial vehicles like forklifts or cooking and heating in homes off-grid.

65
Q

What are alkenes used to produce?

A

Alkenes are used to produce polymers and act as starting materials for the production of many other chemicals.

66
Q

What are alkenes?

A

Hydrocarbons with a double carbon-carbon bond.

(the functional group C=C)

67
Q

What is the general formula for (the homologous series of) alkenes?

A

Cn H2n

68
Q

Explain why alkene molecules are unsaturated.

A

Alkene molecules are unsaturated because they contain two fewer hydrogen atoms than the alkane with the same number of carbon atoms.

69
Q

Name the first four members of the homologous series of alkenes.

A

-ethene
-propene
-butene
-pentene

70
Q

How many bonds does a carbon atom make?

A

4

71
Q

Why are alkenes more reactive than alkanes?

A

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

72
Q

When drawing alkenes using displayed formula, what MUST we do?

A

Make sure the 2nd carbon only has four bonds, not a sneaky extra C-H bond!

73
Q

What determines the reactions of organic compounds?

A

The generality of reactions of functional groups.

74
Q

How do alkenes react with oxygen?

A

In combustion reactions, the same way as other hydrocarbons.

They combust completely in large amounts of oxygen to form carbon dioxide and water.

Without enough oxygen, they undergo incomplete combustion to form carbon monoxide, carbon, water, and sometimes carbon dioxide.

75
Q

Do alkenes tend to combust completely or incompetely when burned?

A

Alkenes tend to undergo incomplete combustion when burned because there isn’t enough oxygen in the air for complete combustion.

76
Q

Why do alkanes tend to burn in the air with smoky flames?

A

Alkanes tend to burn in the air with smoky yellow flames because of incomplete combustion.

-Why is it yellow?

77
Q

Does complete combustion or incomplete combustion release more energy?

A

Complete combustion

78
Q

What is meant by ‘functional group’?

A

A group of atoms in a molecule that determines how that molecule typically reacts.

e.g. the functional group of alkenes is C=C so they all react in similar ways.

(this allows us to predict the products of a reactions).

79
Q

How are alkenes able to react with hydrogen, water and the halogens?

A

The C=C double bond can open up to make a single C-C bond, allowing for the addition of other atoms on the 2 carbons.

These are examples of addition reactions.

80
Q

What is an addition reaction?

A

A chemical reaction where two or more reactants combine to form a single product.

81
Q

Alkene + Hydrogen → ?

A

Alkane

82
Q

Hydrogenation

A

The addition of hydrogen (H₂)

83
Q

Describe the conditions necessary for the addition of hydrogen to alkenes.

A

-A temperature of 60°C
-A nickel catalyst

84
Q

Hept

A

7

85
Q

Alkene + Water → ?

A

Alcohol

86
Q

Describe the conditions necessary for the addition of water to alkenes.

A

-Steam
-A catalyst

-As water must be in the gaseous form, temperatures must be high

87
Q

Describe the conditions necessary for the addition of halogens to alkenes.

A

-Room temperature
-Shake to mix

88
Q

Describe one way of making ethanol industrially.

A

React ethene with steam in an addition reaction to form ethanol.

Pass the reaction mixture into a condenser.

Ethanol and water have a higher boiling point than ethene, so will condense.

Any unreacted ethene gas is recycled back into the reactor.

The alcohol can then be purified from the mixture by fractional distillation.

89
Q

What is an alcohol?

A

A homologous series of organic compounds containing the functional group -OH.

90
Q

What is the suffix for an alcohol?

A

anol

91
Q

What is the general formula for an alcohol?

A

Cn H2n +1 OH
(using subscripts!!)

92
Q

Alkene + Halogen → ?

A

di__o__ane

e.g. Ethene + Bromine → Dibromoethane

93
Q

Ethene + Iodine → ?

A

Diiodoethane

94
Q

List the possible products of: ethane + halogen → ?

(the ones you need to know)

A

Difluoroethane
Dichloroethane
Dibromoethane
Diiodoethane

95
Q

Name the first four alcohols

A

Methanol
Ethanol
Propanol
Butanol

96
Q

What are the ways we can show ethanol? (formulaically)

A

C₂H₅OH

CH₃CH₂OH (this shows the structure of the alcohol better)

97
Q

What are the main uses of alcohols?

A

-They are burned as fuels, used in antibacterial gels, and used as solvents.

98
Q

Describe what happens when any of the first four alcohols react with sodium.

A

Fizzing.

Hydrogen gas would be produced.

99
Q

Describe what happens when any of the first four alcohols burn in air.

A

They undergo complete combustion to produce carbon dioxide and water.

100
Q

What are the products of complete combustion of an alcohol?

A

Carbon dioxide + Water

101
Q

You need to be able to balance equations for the combustion of alcohols.

How should you go about doing this?

A

-The number of carbons is the same as the number of carbon dioxides

-Then check the number of hydrogens are the same

-Re-balance the oxygens using a 1/2

-Double to get whole numbers

102
Q

Describe what happens when any of the first four alcohols react with an oxidising agent/ oxygen from the air.

A

Alcohols are oxidised (gain oxygen) to form a carboxylic acid.

103
Q

Are alcohols flammable?

A

Yes! Therefore, they make very good fuels.

104
Q

What is the pH of alcohols?

A

7 (neutral=green)

105
Q

Why are alcohols such as methanol and ethanol used as solvents in industry?

A

They can dissolve things that water can’t dissolve like hydrocarbons, oils, and fats.

106
Q

Does ethanol smell?

A

No

107
Q

What is ethanol?

A

The alcohol found in alcoholic drinks such as wine or beer.

108
Q

How is ethanol usually made?

A

Using fermentation

109
Q

How is ethanol made less often?

A

Cracking crude oil (to form a shorter alkane and ethene)

Then reacting ethene produced with steam in the presence of a catalyst (hydration)

110
Q

Producing aqueous solutions of ethanol by fermentation.

A

-Sugar solutions are fermented using yeast

-An enzyme in yeast converts the sugars into ethanol (aqueous state as in a solution)

-Carbon dioxide is also produced

111
Q

What is the word equation for producing ethanol using sugar cane?

A

(yeast)
Sugar → ethanol + carbon dioxide

112
Q

What are the conditions for the fermentation of sugar using yeast?

A

-A temperature of around 37°C (optimum)

-A slightly acidic solution

-Under anaerobic conditions

113
Q

What would happen if sugar was fermented in the wrong conditions? (using yeast)

A

Different pH’s or temperatures would cause the enzyme to denature or work at a slower rate.

114
Q

Describe how carboxylic acids can be produced from alcohols.

A

Alcohols can be oxidised to produce carboxylic acids either by leaving them exposed to oxygen in the air or by using an oxidising agent.

115
Q

What are carboxylic acids?

A

A homologous series of compounds with the functional group -COOH.

116
Q

What is the suffix for carboxylic acids?

A

-anoic acid.

117
Q

What are the first four carboxylic acids?

A

methanoic acid
ethanoic acid
propanoic acid
butanoic acid

118
Q

Draw the first four carboxylic acids.

A

Get out of bed and do it

119
Q

How can the structures of carboxylic acids be represented?

A

CH₃ COOH
or using the structural formula (double bonded O and single bonded O-H)

120
Q

What is the general formula for carboxylic acids?

A

CnH2n+1COOH

121
Q

Carboxylic acid + Metal Carbonate → ?

A

Salt + Water + Carbon dioxide

122
Q

How do we work out the name of the salt produced from a carboxylic acid + a metal carbonate?

A

1st name = name of metal
2nd name = eth/prop/but…ANOATE

123
Q

Ethanoic acid + Sodium carbonate → ?

A

Sodium ethanoate + carbon dioxide + water

124
Q

What happens when carboxylic acids dissolve in water?

A

They partially ionise/dissociate into H⁺ ions, forming weak acidic solutions.

125
Q

Explain why carboxylic acids are weak acids.

A

They are only partially ionised in an aqueous solution.
The reaction is reversible (⇄).
pH is 4 to 5

126
Q

Ethanoic acid in water equation?

A

CH₃COOH ⇄ CH₃COO⁻ + H⁺

127
Q

Carboxylic acid + alcohol → ?

A

ester + water

128
Q

What do carboxylic acids need to react with an alcohol?

A

An acid catalyst (e.g. concentrated sulfuric acid).

129
Q

What is the only ester you could be asked about/to name?

A

Ethyl ethanoate.

CH₃COOC₂H₅

130
Q

What are the reactants that produce ethyl ethanoate (and water)?

A

Ethanoic acid + Ethanol
CH₃COOH + C₂H₅

131
Q

Draw ethyl ethanoate.

A

DO IT (It’s an ester x)

132
Q

What type of reaction produces ethanoic acid from ethanol?

A

Oxidation.

133
Q

What does volatile mean?

A

Evaporates easily.

134
Q

Explain why the solution of ethanoic acid has a higher pH than the solution of hydrochloric acid.

A

Ethanoic acid is a weaker acid because it only partially dissociates into hydrogen (H⁺) ions in water.

135
Q

How do we test for an alcohol vs a carboxylic acid?

A

Add a a named carbonate e.g. sodium carbonate

The carboxylic acid will effervesce

The alcohol won’t.

136
Q

Uses of esters?

A

-flavourings
-perfumes

137
Q

What is addition polymerisation?

A

The reaction by which many small molecules (monomers) join together to form very large molecules (polymers).

138
Q

Name some polymers that can be made from alkenes, by addition polymerisation.

A

poly (ethene)
poly (propene)

139
Q

In addition polymers, the repeating unit (bit inside the bracket) has the same atoms as what?

A

The monomer, because no other molecule is formed in the reaction.

BUT the C=C bond becomes a C-C bond!

140
Q

Which functional group exists in alkene monomers?

A

C=C

141
Q

In terms of addition polymerisation, you should be able to…

A

-recognise addition polymers and monomers from diagrams and the functional group C=C in the monomers

-draw diagrams to represent the formation of a polymer from a given alkene monomer

-relate the repeating unit to the monomer.

142
Q

Practice…

A

Drawing diagrams to represent the formation of a polymer from a given alkene monomer. xx

143
Q

What are plastics made of?

A

Polymers, which are usually carbon based (with alkene monomers.)

144
Q

What are the conditions necessary for addition polymerisation?

A

-Pressure
-A catalyst

145
Q

Does it matter what’s attached to the repeating unit in polymers?

A

No - the only thing reacting is the carbons in the middle! You could get a funny lil’ shape or something but ignore and do the normal process!

146
Q

What polymer would tetrafluoroethene form?

A

poly (tetrafluoroethene)

its as easy as putting poly (name of o.g. compound)

147
Q

What must we remember when drawing addition polymerisation reactions?

A

The little n both in front of the alkene, and outside the bracket of the polymer.

148
Q

Which alcohol is found in wine and beer?

A

Ethanol.

Chemistry (14 decks)

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