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Higher Chemistry Unit 2 > Part 1 > Flashcards

Part 1 Flashcards

1
Q

Are oil, natural gas and coal infinite resources?

A

No, they are finite (no renewable).

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2
Q

From oil, natural gas and coal, what can we get and what can they be used for?

A

We can get carbon compounds that can be used as fuels or feedstocks.

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3
Q

What is a feedstock?

A

A chemical from which other chemicals can be manufactured.

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4
Q

Can one chemical sometimes be used as both a fuel or a feedstock?

A

Yes.

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5
Q

What is an example of a chemical that can be used both as a feedstock and as a fuel.

A

The naptha fraction from crude oil distillation can produce petrol (a fuel) or it can be used as a feedstock to produce ethene and then polythene.

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6
Q

Draw out the consumer products containing carbon compounds.

A

.

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7
Q

How have these molecules (consumer products, page 1) been created?

A

They have been synthesised (built up) from small reactive molecules.

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8
Q

What is the main source for the consumer products compounds?

A

Crude oil

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9
Q

Why is the petrol fraction produced by distillation of crude oil not ready to use as car fuel?

A
  1. it is a low quality fuel.

2. there is not enough of it to satisfy market demand for petrol.

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10
Q

Why is the petrol fraction a poor quality petrol?

A

It contains mostly straight chain hydrocarbons.

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11
Q

What happens when ignited in the combustion chamber of the engine?

A

The straight chain hydrocarbons tend to explode rather than burn smoothly.

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12
Q

What are these explosions (when the straight chain hydrocarbons explode rather than burn smoothly) called?

A

Auto-ignition or knocking and can damage the engine.

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13
Q

What does petrol contain to make it burn more smoothly?

A

Branched, cyclic and aromatic hydrocarbons.

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14
Q

What does leaded petrol contain to make it burn more smoothly?

A

The additive lead tetra-ethyl, Pb(C2H5)4

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15
Q

What is the additive lead tetra-ethyl?

A

An antiknock agent and helps poor quality petrol to burn smoothly.

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16
Q

What else does petrol contain?

A

Dibromoethane.

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17
Q

What does dibromoethane do?

A

Combines with the lead which then leaves the exhaust as volatile lead (11) bromide.

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18
Q

What is wrong with dibromoethane combining with the lead and leaving the exhaust volatile lead (11) bromide?

A

Lead is poisonous so unleaded petrol was produced.

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19
Q

What makes unleaded petrol burn smoothly?

A

An even greater amount of branched and aromatic hydrocarbons.

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20
Q

How is the quantity of the petrol fraction increased?

A

By using the naphtha fraction and waxy distillate. First though, the quality must be improved.

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21
Q

Explain how is this quantity of the petrol fraction increased?

A

The naphtha fraction is mostly straight C5 to C10 hydrocarbons (the correct size of molecules for petrol). The waxy distillate consists of C20 to C40 hydrocarbons (also correct). These are first cracked to reduce the chain length. We now have molecules that are the correct size but are still straight chained.

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22
Q

What is reforming?

A

Reforming is a chemical reaction which changes the structure of the molecules without changing their size.

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23
Q

What does reforming of the naphtha fraction and the products of cracking give?

A

Aromatics, cycloalkanes and branched chain products as well as some straight chain compounds.

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24
Q

e.g. the reforming of octane

A

draw it out.

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25
Q

These are blended with the original petrol fraction to do what?

A

Increase both the quality and the amount.

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26
Q

Have a look at the flow diagram on page 3 at the top.

A

Seriously, do it.

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27
Q

Why is it important to have the correct mix of volatile compounds?

A

Petrol is drawn in to an engine as a vapour

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28
Q

Does the mix of volatile compounds in petrol depend on the time of year?

A

Yes, in winter more volatile compounds are added (e.g. butane and pentane) and in summer, the blend has a larger proportion of slightly larger hydrocarbons.

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29
Q

What kind of molecules does petrol contain?

A

Small (C5 to C10) volatile hydrocarbon molecules.

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30
Q

How are they ignited?

A

By an electric spark from the spark plug.

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31
Q

Look at the other diagram on page 3.

A

SERIOUSLY, GOD. JUST DO IT. It’s IMPORTANT.

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32
Q

The burning of fossil fuels yields products that can harm the environment. What is the effect of carbon dioxide?

A

Contributes to the green house effect.

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33
Q

Carbon monoxide?

A

Produced by incomplete combustion is toxic.

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34
Q

Sulphur dioxide?

A

Sulphur is a common impurity in fuels and, unless it is removed, it produces sulphur dioxide when the fuel is burned. Sulphur dioxide is a major contributor to acid rain.

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35
Q

Nitrogen oxides?

A

The spark in a car engine, as well as igniting the petrol, produces nitrogen oxides (NOx) from the nitrogen and oxygen of the air. They cause respiratory problems and also dissolve in water and add to the “acid rain” problem.

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36
Q

Lead compounds?

A

resulting from leaded petrol are poisonous. Evidence suggests that accumulations of lead in the body can cause brain damage especially in young children.

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37
Q

What are some alternative liquid fuels?

A

Ethanol and methanol.

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38
Q

Ethanol is the alcohol which is formed when…

A

sugar (glucose) ferments. In countries where sugar cane can be grown in great quantities (e.g. Brazil) ethnaol is produced and mixed with petrol. It is also possible to manufacture methanol on an industrial scale; this can be used as fuel directly or mixed with petrol.

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39
Q

What is the equation for methanol burning?

A

CH3OH + 3/2 O2 -> CO2 + 2H2O

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40
Q

Advantages of using methanol?

A
  • complete so reducing the carbon monoxide in the air
  • petrol contains benzene and other aromatic hydrocarbons which are carcinogenic and methanol doesn’t contain these
  • relatively quite cheap and renewable
  • less volatile and less likely to be an explosion risk
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41
Q

Disadvantages?

A
  • toxic and can cause blindness/brain damage
  • produces less energy than petrol for equiv. volume
  • absorbs water giving a corrosive mixture
  • methanol and petrol are quite immiscible (don’t mix readily)
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42
Q

Internal combustion engines could be designed to use hydrogen burning instead of petrol. Why is this good?

A

Very efficient and reduce the amount of carbon dioxide in the atmosphere.

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43
Q

What is the equation?

A

2H2 + O2 -> 2H2O

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44
Q

Hydrogen produces ____ energy than petrol, weight for weight.

A

MORE

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45
Q

However…

A

Hydrogen is the lightest and least easily liquefied gas. Volume for volume, hydrogen is less energy efficient than petrol.

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46
Q

What else can hydrogen be used for?

A

To make electricity from a hydrogen/oxygen fuel cell. This would involve allowing the hydrogen and oxygen to react in two separate parts of the cell and making electricity instead of heat.

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47
Q

Anything else hydrogen can be used for?

A

Could be stored and distributed like natural gas and used for heating in houses. Poss cheaper than using leccy.

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48
Q

What is this known as? (using hydrogen)

A

Hydrogen economy.

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49
Q

What is the problem with hydrogen economy?

A

Could be v efficient if we didn’t need fossil fuels to make the hydrogen in the first place (electricity is required to make the hydrogen and this leccy is still made largely by burning fossil fuels).

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50
Q

What would be the perfect solution to the hydrogen economy problem?

A

Solar energy to ‘split’ water into hydrogen and oxygen would be a perfect solution.

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51
Q

What is biomass?

A

General term for plant material.

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52
Q

What’s biogas?

A

when waste plant material (e.g. manure, straw, veg) decays in the absence of air, bacteria produce it. It’s called anaerobic fermentation. Consists mainly of methane (60%) and carbon dioxide.

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53
Q

There are over 15,000,000 different carbon compounds

A

Cool

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54
Q

How does this arise?

A

From carbon’s ability to join in straight chains, branched chains and rings as well as its ability to form strong bonds with many types of atom.

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55
Q

What features does a homologous series have? Name the first.

A

There is a gradual change in physical properties from one member to the next. The most common example of this is the increasing melting and boiling points as we go up a series. The reason of course is the increasing van der Waals forces as the molecules get larger.

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56
Q

2nd?

A

Members have similar chemical properties and methods of preparation.

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57
Q

3rd

A

The formula increases by CH2 from one member to the next up the series.

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58
Q

4th

A

Series has a general formula.

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59
Q

5th

A

all members have the same functional group.It’s this that gives the series its characteristic reactions.

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60
Q

Alkanes general formula?

A

CnH2n+2

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61
Q

Why are they called saturated hydrocarbons?

A

Because all the carbon atoms have formed the max no. of single covalent bonds.

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62
Q

What two main types of reaction can alkanes undergo?

A

Combustion and substitution.

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63
Q

Alkanes burn in plenty oxygen to form…

A

carbon dioxide and water

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64
Q

What’s the equation of alkane combustion?

A

C3H8+5O2 -> 3CO2 + 4H2

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65
Q

Substitution - look at page 7

A

GOOOO

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66
Q

Are substitution reactions of alkanes fast or slow?>

A

Slow

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67
Q

All the _____ can react with alkanes in this way.

A

Halogens (chlorine, fluorine and iodine etc)

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68
Q

What are isomers?

A

Molecules with the same molecular formula but different structural formulae

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69
Q

First the first ____ members of the alkanes only one structure is possible but butane, C4H10 has two isomers.

A

3

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70
Q

Look at the structures on p7

A

Yes. Now.

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71
Q

What are the rules for naming?

A
  1. Find the longest carbon chain in the molecule - the name is based on the alkane with this number of carbon atoms.
  2. Number the chain to give any branches the lowest possible number.
  3. Name the branches (methyl -CH3, ethyl -C2H5 etc)
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72
Q

What is the general formula of the alkenes?

A

CnH2n.

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73
Q

Draw out the structural formula for the first 3.

A

Page 8.

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74
Q

Why are alkenesunsaturated?

A

Each member has a C=C bond. This is the functional group.

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75
Q

How do isomers arise?

A

By branching the chain and by varying the position of the double bond.

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76
Q

Is naming different for alkenes?

A

It’s similar but the main chain (the longest) must contain the double bond, whose position is indicated by a number. The chain is numbered to make this number as small as possible.

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77
Q

Draw out the isomers of pentene on p.8

A

ayeeee

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78
Q

How are ethene and propene made?

A

By cracking of either ethane or naphtha.

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79
Q

What does cracking of either ethane or naphtha involve in terms of feedstocks?

A

Heating it to a very high temperature (800 degrees Celsius).

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80
Q

Both feedstocks (ethane and naphtha) give the same products but the _____ are different.

A

proportions

81
Q

As we can see, ethane provides a much higher percentage of ethene but…

A

naphtha gives other valuable by-products.

82
Q

If propane is cracked, the main product is what?

A

Propene

83
Q

In common with all hydrocarbons, the alkenes burn in plenty oxygen to form…

A

carbon dioxide and water

84
Q

What is the equation for the combustion of alkenes?

A

C2H4 + 3O2 -> 2CO2 + 2H2O

85
Q

The characteristic reaction of alkenes are addition reactions - in these…

A

a molecule adds across the double bond

86
Q

Addition reactions involving alkenes and the addition of bromine water are called…

A

bromination

87
Q

In the bromination reaction, the bromine loses its ____ colour very quickly.

A

brown

88
Q

What is the name of the addition reaction when hydrogen is added?

A

Hydrogenation

89
Q

This addition of hydrogen across a double bond happens only in the presence of a…

A

catalyst (Pt)

90
Q

What does hydrogenation do in terms of alkanes and alkenes?

A

It converts an alkene to an alkane.

91
Q

What is the third addition reaction for alkenes?

A

with hydrogen halides

92
Q

What happens in the hydrogen halides addition reaction in alkenes?

A

We end up with a substituted alkane - a haloalkane. There is a possibility of isomeric products.

93
Q

What is the fourth addition reaction in alkenes?

A

Hydration.

94
Q

In the hydration in alkenes reaction, what is necessary?

A

high temp and high pressure

95
Q

What happens in all the addition reactions in alkenes?

A

An unsaturated compound becomes fully saturated.

96
Q

What is the functional group of the alkynes.

A

The carbon to carbon triple bond

97
Q

Are alkynes more or less saturated than alkenes?

A

MORE

98
Q

How do you name an alkyne?

A

It’s the same as alkenes apart from the ending being yne rrather than ene

99
Q

What’s the general formula of the alkynes?

A

CnH2n-2

100
Q

What’s the molecular formula for ethyne?

A

C2H2

101
Q

Draw out the structural formula for ethyne

A

k

102
Q

Draw out the molecular formula and the structural formula for for propyne

A

k

103
Q

Molecular formula and structural formula for butyne

A

k

104
Q

What’s the combustion equation of a hydrocarbon?

A

C2H2 + 5/2 O2 -> 2CO2 + H20

105
Q

As the alkynes are unsaturated we might expect they will undergo addition reactions like the alkenes. This is indeed the case but the reaction can happen in two stages and…

A

with care, can be stopped after the first stage

106
Q

What’s the first addition reaction with alkynes?

A

with halogens to make dihaloalkenes, then tetrahaloalkanes.

107
Q

What is the 2nd addition reaction with alkynes?

A

With hydrogen to make alkenes and then alkanes. Using hydrogen and Pt (catalyst)

108
Q

What’s the 3rd addition reaction with alkynes?

A

with hydrogen halides to haloalkenes and then dihaloalkanes. Added HCl

109
Q

A number of the reactions of alkanes, alkenes and alkynes have produced products containing…

A

halogen atoms.

110
Q

What are halogenalkanes?

A

Alkane molecules where halogen atoms have replaced at least one hydrogen atoms.

111
Q

What are the most widely heard about haloalkanes?

A

The CFCs - chlorofluorocarbons

112
Q

What do the CFCs contain?

A

Chlorine and flourine in their molecules and halons which contain carbon, chlorine, fluorine and bromine atoms.

113
Q

Draw out the e.g.s of CFCs on p.11

A

k

114
Q

What are the properties of the CFCs?

A

They’re really unreactive, have low flammability and generally low toxicity.

115
Q

What situations are CFCs useful for?

A
  • aerosol propellants
  • regrigerants
  • blowing agents
  • cleaning solvents
116
Q

Explain how aerosol propellants using CFCs work

A

When the valve of an aerosol can is pushed, the pressure inside drops and that allows the CFC inside to vaporise. This then acts as the propellant, carrying the contents of the can into the atmospjere. Because of the environmental hazards, CFCs have been replaced by butane in aerosol cans.

117
Q

Look at the other explanations of CFCs usefulness in certain situations oon p11

A

wooooop

118
Q

Steps have been taken to control the use and the release of CFCs into the atmosphere because…

A

of its effect on the ‘ozone layer’ in the upper atmosphere

119
Q

What is Ozone (O3)?

A

A vital natural sunscreen gas which protects us from very harmful UV radiation by absorbing it.

120
Q

How is ozone formed?

A

It is formed between oxygen atoms and oxygen molecules and breaks back down to oxygen molecules and atoms by absorption of UV light.

121
Q

What’s the equation for the formatin of ozone?

A

O + O2 -> O3. It’s also reversible so double arrow needed

122
Q

The oxygen atoms are produced by oxygen molecules, also by aborbing some UV radiation. Equation pls

A

O2 -> 2O (not reversible yo)

123
Q

It is widely accepted that certain CFCs in the atmosphere can ___ the ozone layer and this would allow more UV radiation to reach the earth.

A

destroy

124
Q

What does the CFC destroying the ozone layer result in?

A

More incidents of skin cancer, eye cataracts and could have many other wide-ranging effects on the environment.

125
Q

What is one of the reasons that there are so many carbon compounds?

A

Ring compounds can also easily be formed cyclic compounds

126
Q

An example of ring compoounds

A

cycloalkanes

127
Q

What is the smallest cycloalkane?

A

Cyclopropane

128
Q

p.13

A

look at table and draw

129
Q

What is general equation of the cycloalkanes?

A

The same as the alkene - they’re isomeric

130
Q

How do cycloalkanes react?

A

In the same way as the alkanes - combustion and substitution.

131
Q

Cycloalkenes and cycloalkynes are other possible homologous series of ___ compounds

A

cyclic

132
Q

How do cycloalkenes and cycloalkynesreaction?

A

Like the alkenes and alkynes.

133
Q

Cycloalkenes are ____ with alkynes

A

Isomeric

134
Q

What important group can be produced from naphtha (which comes from the distillation of crude oil)?

A

The aromatic hydrocarbons

135
Q

What is cyclisation?

A

When straight chain alkanes (in naphtha) form cycloalkannes which then lose hydrogen to form aromatic hydrocarbons (reforming).

136
Q

e.g. of aromatic hydrocarbons

A

benzene

137
Q

What is reforming?

A

The structure of the molecule alters without any change in their size.

138
Q

With heptane, the reforming process leads to…

A

methylbenzene (toluene)

139
Q

The process of reforming gives…

A

a mixture of aromatic compounds that must be carefully sepparated

140
Q

What is the simplest aromatic compound?

A

Benzene C6H6

141
Q

Draw benzene p14

A

yah

142
Q

The formula of benzene seems v unsaturated but

A

the benzene ring is v resistant to addition reactions - there is no fast reaction with bromine water

143
Q

The structure of benzene. This takes up 3 of the 4 bonding electrons from each carbon atom. The 4th can be imagined as being shared over the whole ring.

A

k

144
Q

What are the electrons like in benzene?

A

They are delocalised and this delocalisation gives the benzene ring gr8 stability. Unresistant to attack and quite unreactive.

145
Q

All aromatic molecules are based on the…

A

benzene unit

146
Q

In the molecule methylbenzene (toluene), C6H5Ch3, one of the H has been replaced with…

A

a methyl group CH3

147
Q

In methylbenze, another way to look at is that the methane molecule has a hydrogen replaced with…

A

the aromatic part C6H5.

148
Q

What is the C6H5 group called?

A

The phenyl group

149
Q

look at the summary of benzene and phenyl on p.15

A

k

150
Q

How are dimethylbenzenes formed?

A

When two hydrogen atoms in benzene are plaaced with methyl groups

151
Q

What are the 3 isomers of dimethylbenzene?

A

Draw them. They are 1,2-dimethylbenzene, 1,3 dimethylbenzene and 1,4 dimethylbenzene (p.15)

152
Q

What are the isomers of dimethylbenzene also called?

A

Xylenes

153
Q

What are xylenes used for?

A

Manufacturing paints, fibers and dyes

154
Q

Benzene is a very important…

A

feedstock

155
Q

What is most of the benzene reacted with?

A

Ethene to form phenylethene (styrene)

156
Q

What is phenlyethene used to make?

A

The polymer poly (phenylethene) also known as polystyrene.

157
Q

What is methylbenzene used to make?

A

TNT (trinitrotohere)

158
Q

Examples of derivatives of benzene?

A

phenol, benzoic acid and phenylamine (Aniline)

159
Q

Derivatives of benzene used in the manufacture of…

A

bakelite, nylon monomers, drugs (e.g. Aspirin) and dyes, germicides (dettol)

160
Q

What is the functional group of the alcohols (alkanols)?

A

The OH group

161
Q

What is the general formula of the alcohols (alkanols)?

A

CnH2n+1OH

162
Q

What are the three groups of alkanols?

A

Primary alcohols, secondary and tertiary

163
Q

define primary alkanol group

A

the carbon attached to the OH group is directly bonded to only one alkyl group

164
Q

define seconary alkanol group?

A

the carbon attached to the OH group is bonded to two alkyl groups directly

165
Q

define tertiary alcohol group?

A

carbon attached to the OH group is bonded to three alkyl groups directly

166
Q

How can isomers result?

A
  1. chain brancing

2. varying the position of the OH group

167
Q

The main chains of the alkanols must contain…

A

the OH group

168
Q

Look at the four isomers of butane on p.16

A

cool

169
Q

keep going, you got thissss

A

!!!!!!!!!!!!!

170
Q

What are the two ways to prepare ethanol?

A
  1. Fermentation.

2. Hydration of alkenes.

171
Q

Describe fermentation

A

Ethanol can be produced from carbs by fermentation catalysed by enzymes present in yeast

172
Q

What does fermentation produce ethanol for?

A

ALCOHOLIC DRINKS

173
Q

What is the fermentation equation?

A

C6H12O6 - yeast enzymes -> 2C2H5OH + 2CO2

174
Q

Describe hydration of alkenes

A

Ethanol is prepared industrially by reacting ethene with steam at high temperature, high pressure in the presence of a catalyst. It was invented to met market demand for ethanol for industrial uses.

175
Q

This reaction (hydration of alkenes), in which the water adds across the double bond, is also called…

A

catalytic hydration.

176
Q

What can catalytic hydration be extended to make?

A

Other alcohols - hydration of propene gives propanol, hydration of butene gives butanol.

177
Q

In some cases of catalytic hydration, the products are…

A

isomeric.

178
Q

Why can’t methanol be prepared by hydration of the C=C bond of an alkene?

A

It only has one carbon

179
Q

How is methanol industrially prepared?

A

From synthesis gas which is a mixture of carbon monoxide and hydrogen.

180
Q

How is synthesis gas prepared?

A

By passing methane and steam at a very high temperature over a catalyst.

181
Q

What is the equation for the industrial prepartion of methol?

A

CH4 + H2O -> CO + 3H2

182
Q

What is the industrial preparation of methanol called??

A

The steam reforming of methane.

183
Q

Methanol is a very important feedstock in industry why?

A

It is converted to methanal and then to thermosetting plastics as we will see later.

184
Q

What else is synthesis gas used for?

A

It provides the hydrogen for the Haber process for ammonia production.

185
Q

What also does synthesis gas provide?

A

The hydrogen for the Haber process for ammonia production.

186
Q

Look at the diagram on the top of page 18

A

lol

187
Q

look at diagram on p18 top

A

k

188
Q

Physical Properties of Alknaols: Describe their solubility in water

A

The first 3 alkanols are miscible with water because the polar hydroxyl group can hydrogen bond with water molecules

189
Q

Physical Properties of Alkanols: Describe acidity

A

Not acidic in water so do not give any of the usual acid reactions

190
Q

What are the three main chemical reactions of alkanols?

A
  1. Dehydration to alkenes
  2. Complete oxidation
  3. Partial oxidation
191
Q

Describe the dehydration to alkenes

A

If an alcohol is passed over hot aluminimum oxide as catalyst, water is removed from the alcohol and then alkene is formed

192
Q

look at bottom of p.18

A

cool

193
Q

What else can be used as a catalyst for the dehydration to alkenes?

A

Concentrated sulphuric acids which has a strong attraction for water. Different isomers can be formed in this reaction bc of the OH and H from carbon atoms next to each other in large alkanols are removed.

194
Q

Describe complete oxidiation

A

Combustion alcohols burn and in excess oxygen the products are carbon disoxide and water

195
Q

Describe partial oxidation

A

The products of the oxidation of alcohols depend on whether the alcohol is primary, secondary or tertiary.

196
Q

Look at the equations on p.18 and 19 and the diagrams

A

kooool

197
Q

Acidified potassium permanganate solution can be used as an oxidising agent for the partial oxidation of an alcohol. What happens?

A

During the reaction the purple permanganate ion is reduced to colourless ions.

198
Q

Acidified potassium dichromate solution can be used as an oxidising agent for PO of an alcohol. whathappens?

A

The orange dichromate ion is reduced to green ions

199
Q

Copper (11) oxide and heat (oxidising agent for PO of alcohol). What happens?

A

Black oxide is reduced to reddish copper metal during the reaction.

Higher Chemistry Unit 2 (6 decks)

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