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GCSE - Chemistry (New) > Section 3 - Pgs 45-48 > Flashcards

Section 3 - Pgs 45-48 Flashcards

1
Q

What is a homologous series?

A

A group of compounds that can all be represented by the same general formula.

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2
Q

What colour flame does incomplete combustion of alkanes produce?

A

Smoky yellow

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3
Q

What are the first 4 alkenes called?

A

1) Ethene
2) Propene
3) Butene
4) Pentene

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4
Q

Compare the two methods of producing ethanol in terms of rate of reaction.

A

Ethene and steam: Very fast

Fermentation: Slow

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5
Q

What is the temperature, pressure and catalyst used for making ethanol from ethene and steam?

A
  • 300*C
  • 60-70 atm
  • Phosphoric acid
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6
Q

What is a general formula?

A

An empirical formula that represents the composition of any member of an entire class of compounds.

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7
Q

Is there a molecule called “methene”?

A

No, there is not enough carbons to have a double bond. The first alkene is ethene.

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8
Q

What types of reactions do alkanes undergo?

A
  • Combustion

- Substitution reactions

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9
Q

What is the process of turning ethanol into ethene called?

A

Dehydration -> Water needs to be removed

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10
Q

What colour flame does complete combustion of alkanes produce?

A

Blue

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11
Q

Compare the two methods of producing ethanol in terms of purity of the product.

A

Ethene and steam: Pure

Fermentation: Very impure -> Needs further processing

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12
Q

What is the general formula of alkanes?

A

CnH2n+2

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13
Q

How many carbon atoms are in ethane?

A

2

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14
Q

What is the general formula of alkenes?

A

CnH2n

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15
Q

What is the word equation for ethene reacting with bromine?

A

Ethene + Bromine -> Dibromoethane

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16
Q

What is organic chemistry?

A

Chemistry that deals with carbon compounds.

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17
Q

Write a symbol equation for the production of ethanol by fermentation.

A

C6H12O6 -> 2C2H5OH + 2CO2

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18
Q

Describe how ethene and steam can be used to produce ethanol.

A
  1. Ethene is taken from crude oil
  2. Ethene reacts with steam to produce ethanol
  3. Temperature of 300*C and 60-70 atm
  4. Phosphoric acid used as catalyst
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19
Q

Explain in detail the two ways in which a haloalkane can be formed.

A

Substitution in alkanes:

1) In the presence of UV light, a hydrogen atom in an alkane can be replaced by a bromine or chlorine atom.
2) The hydrogen that was replaced then reacts with the second halogen in its molecule, forming, for example, hydrogen bromide.

Addition in alkenes:

1) A C=C bond is split, allowing each of the two carbons to bind to a halogen atom.
2) There are no other products.

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20
Q

What is the general word equation for complete combustion of alkanes?

A

Alkane + Oxygen -> Carbon Dioxide + Water (+ Energy)

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21
Q

What are alkanes?

A

Alkanes are a homologous series of saturated hydrocarbons with the general formula: CnH2n+2.

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22
Q

What types of reactions do alkenes undergo?

A
  • Combustion

- Addition reactions

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23
Q

What does saturated mean?

A

Containing only single bonds (so that no more molecules or atoms can join onto the molecule).

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24
Q

How can you test for the presence of carbon-carbon double bonds (i.e. whether a hydrocarbon is saturated or unsaturated)?

A

1) Shake the hydrocarbon with orange bromine water.

2) If the solution turns colourless, C=C bonds are present. If it doesn’t, then they are not.

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25
Q

How many carbon atoms are in propane?

A

3

26
Q

How many carbon atoms are in pentane?

A

5

27
Q

What is a substitution reaction?

A

When an atom is replaced by another. In alkanes, this is usually a hydrogen, which is replaced by a different atom (e.g. bromine)

28
Q

Why does the bromine water test for carbon-carbon double bonds work?

A

1) The bromine is orange at first.
2) Adding an alkene causes the double bond to open up, adding the bromine to the molecule and making a dibromoalkane.
3) The dibromoalkane is colourless and there are no bromine molecules to give the solution an orange colour. This makes the solution colourless.

29
Q

Give the symbol equation for turning ethanol into ethene.

A

C2H5OH -> C2H4 + H2O

30
Q

Describe the process of turning ethanol into ethene.

A

Ethanol vapour is passed over a hot catalyst of aluminium oxide. (Diagram Pg 48 of revision guide)

31
Q

What are alkenes?

A

Alkenes are a homologous series of unsaturated hydrocarbons with the general formula: CnH2n.

32
Q

Compare the two methods of producing ethanol in terms of the availability of raw materials.

A

Ethene and steam: Ethene is from oil -> Finite resource

Fermentation: Sugar -> A renewable resource

33
Q

How do alkanes react with halogens?

A

They can react with chlorine or bromine (halogens) to make haloalkanes in the presence of UV light. This is an example of a substitution reaction.

34
Q

When do complete and incomplete combustion of alkanes happen?

A
  • Complete combustion happens when there is sufficient oxygen
  • Incomplete combustion happens when there is insufficient oxygen
35
Q

What are hydrocarbons?

A

Molecules made up of hydrogen and carbon atoms only.

36
Q

Give an example of a substitution reaction.

A

In the presence of UV light, methane reacts with bromine and a single bromine atom replaces a hydrogen atom in the methane molecule.

37
Q

How many carbon atoms are in methane?

A

1

38
Q

What is the general word equation for incomplete combustion of alkanes?

A

Alkane + Oxygen -> Carbon + Carbon Monoxide + Carbon Dioxide + Water (+ Energy)

39
Q

Apart from ethanol, what else is produced during the fermentation of sugar?

A

Carbon dioxide

40
Q

What is the word equation for methane reacting with bromine?

A

Methane + Bromine -> Bromomethane + Hydrogen bromide

41
Q

How do alkenes react with halogens?

A

They make haloalkanes. This is an example of an addition reaction.

42
Q

How many carbon atoms are in butane?

A

4

43
Q

What are the products of complete and incomplete combustion of alkanes?

A 
Complete:
- Carbon Dioxide
- Water
Incomplete:
- Carbon Dioxide
- Water
- Carbon
- Carbon Monoxide
44
Q

How many covalent bonds can a hydrogen atom make?

A

1

45
Q

Compare the two methods of producing ethanol in terms of the continuity of the process.

A

Ethene and steam: Continuous

Fermentation: Batch

46
Q

How do alkenes combust?

A

Just like alkanes do.

47
Q

How many more atoms can join onto a double carbon in an alkene and why?

A

2 - The double bond opens up, meaning that the carbon either side of the bond can make an extra single bond with another atom.

48
Q

Compare the two methods of producing ethanol in terms of cost.

A

Ethene and steam: High equipment cost + Low labour cost

Fermentation: Low equipment cost + High labour cost

49
Q

What are isomers?

A

Molecules with the same molecular formula but different structures.
(e.g. Butene can have the double bond on a different pair of carbons in each isomer)

50
Q

Describe how fermentation can be used to produce ethanol.

A
  1. Raw material is sugar
  2. Yeast is used to convert sugar into ethanol
  3. Temperature of 30*C
51
Q

What is a symbol equation for the incomplete combustion of methane?

A

4CH4 + 6O2 -> C + 2CO + CO2 + 8H2O

(However, this is just an example. The products depend on the amount of oxygen. For example, there could be 7O2, but no carbon is produced.)

52
Q

What does unsaturated mean?

A

Containing at least one double bond (so that they can make more bonds and other atoms or molecules can join onto the molecule).

53
Q

What catalyst is used in turning ethanol into ethene?

A

Aluminium oxide

54
Q

What are the advantages of complete combustion of alkanes over incomplete combustion?

A
  • Releases more energy

- No poisonous gases

55
Q

What is a good mnemonic for remembering the first 4 alkanes/alkenes?

A

Mice
Eat
Peanut
Butter

(Methane, Ethane, Propane, Butane)

56
Q

What are the first 5 alkanes called?

A

1) Methane
2) Ethane
3) Propane
4) Butane
5) Pentane

57
Q

What are haloalkanes?

A

Molecules which are formed when a halogen reacts with an alkane or alkene.

58
Q

What are the two methods of producing ethanol?

A
  • Fermentation

* Ethene and steam

59
Q

Write a symbol equation for the production of ethanol from ethene and steam.

A

C2H4 + H2O -> C2H5OH

60
Q

What is the symbol equation for the complete combustion of methane?

A

CH4 + 2O2 -> CO2 + 2H2O

61
Q

How many covalent bonds can a carbon atom make?

A

4

GCSE - Chemistry (New) (18 decks)

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