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GCSE Chemistry > Topic 9 - Separate Chemistry 2 > Flashcards

Topic 9 - Separate Chemistry 2 Flashcards

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1
Q

What are hydrocarbons ?

A

Hydrocarbons are organic compounds made of only carbon and hydrogen

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2
Q

What are the dominant compounds in crude oil ?

A

Hydrocarbons

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3
Q

In alkanes how many bonds do carbon atoms need ?

A

carbon atoms bond to four atoms (hydrogen or carbon).

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4
Q

Why do we call alkanes saturated hydrocarbons ?

A

We call them saturated hydrocarbons as all their bonds with other atoms are single bonds.

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5
Q

Do alkanes have a high or low reactivity ?

A

quite low reactivity, but they combust quite well.

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6
Q

Why are alkanes useful as fuels ?

A

quite low reactivity, but they combust quite well.

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7
Q

What is the alkanes genral formula ?

A

Alkanes have the general formula CnH(2n+2)
E.g. if a hydrocarbon contained 7 carbon atoms, the number of hydrogen atoms would be
(2 x 7) + 2 = 16
So, the formula for the hydrocarbon shown in the image would be C7H16

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8
Q

What are the 4 smallest alkanes in ascending order ?

A

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

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9
Q

What are the three last letters of all alkanes?

A

anes

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10
Q

What is the functional group of alkenes ?

A

Alkenes are hydrocarbons with the functional group C=C

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11
Q

Why are alkenes reactive ?

A

The presence of the C=C functional group means that alkenes have greater reactivity than alkanes.

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12
Q

What is a homologous series ?

A

A homologous series is a series of compounds with the same general formula.

Alkenes are a homologous series with the general formula CnH2n.

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13
Q

What are alkenes ?

A

Alkenes are unsaturated hydrocarbons because they contain a double bond between two of their carbon atoms (C=C).

This means that an alkane and alkene with the same length of carbon chain will have different numbers of hydrogen atoms - the alkane will have two more hydrogen atoms.

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14
Q

What arethe 4 smallests alkenes ?

A

Ethene - C2H4
Propene - C3H6
Butene - C4H8
Pentene - C5H10

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15
Q

What do Alkenes all end in ?

A

Ene

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16
Q

What are functional groups ?

A

Functional groups are a collection of atoms that impact the reactions of an organic compound.

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17
Q

What are the functional group of alkenes ?

A

The functional group of alkenes is C=C (a carbon-carbon double bond).

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18
Q

Whats an adition reaction ?

A

Addition reactions are normal for alkenes. In these reactions, the C=C bond opens up and allows carbon atoms to bond with new atoms.

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19
Q

What test can be used as a test to distinguish between alkenes and alkanes ?

A

Alkenes, unlike alkanes, will react when shaken with bromine water. This causes the solution to change colour from orange-brown to colourless.

E.g. ethene (C2H4) (colourless) + bromine (Br2) (orange-brown solution) → dibromoethane (CH2BrCH2Br) (colourless).

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20
Q

What happens between the reaction of alkenes + water ?

A

When a phosphoric acid catalyst is present, alcohols can be formed by reacting alkenes with steam.

E.g. Ethene (C2H4) + steam (H2O) → ethanol (C2H5OH)

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21
Q

What happens in a reaction between ethene + hydrogen ?

A

When a nickel catalyst is present, alkanes can be formed by combining hydrogen with an alkene.

E.g. Ethene (C2H4) + hydrogen (H2) → ethane (C2H6)

Adding hydrogen atoms across a carbon-carbon double bond is called hydrogenation.

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22
Q

What happens in a reaction between alkenes + oxygen ?

A

Alkenes can be involved in combustion reactions with oxygen. The outcome of these reactions is similar to when other hydrocarbons react with oxygen.

E.g. Ethene (C2H4) + oxygen (O2) → carbon monoxide (CO) + carbon (C) + water (H2O)

Because their combustion is incomplete, they burn with smoky flames

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23
Q

The equations for the combustion (burning) of hydrocarbons depend what ?

A

on the amount of oxygen that is available

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24
Q

What is created if alkames are burned without enough oxygen ?

A

2C + O2 → 2CO

25
Q

What are the properties of carbon monoxide gas ?

A

Colourless
Toxic
Odourless

26
Q

What does the The combustion (burning) of hydrocarbons when there is a good air supply involve ?

A

Energy release.

The oxidation of carbon and hydrogen to create carbon dioxide and water.

27
Q

Why do Short-chain hydrocarbon fractions of crude oil burn easily ?

A

Ignite easily
Are highly volatile
Have low boiling points

28
Q

What is a typical reaction for alkenes?

A

Addition

29
Q

What are polymers ?

A

Polymers are large, chain-like molecules that can extend for thousands of atoms

30
Q

What are polymers help together by ?

A

Strong covalent bonds between atoms in molecules.

Weak intermolecular forces between molecules.

31
Q

Because of the large size of polymer molecules what does this do to the imtermolecular forces ?

A

Because of the large size of polymer molecules, the intermolecular forces add up to be quite strong.

32
Q

What state are polymers at room temperature ?

A

So, polymers are usually solid when at room temperature.

33
Q

Why do polymers melt easily ?

A

many polymers melt easily because the intermolecular forces remain less strong than chemical bonds.

34
Q

What is addition polymerisation ?

A

Addition polymerisation is the joining of short-chain monomers to produce one long-chain polymer.

35
Q

What are the monomers in addition polymerisation ?

A

Alkenes are the monomers used in addition polymerisation.

This is because the carbon-carbon double bonds in alkenes can open up to allow multiple alkenes to join together

36
Q

What are the products of addition polymerisation ?

A

In addition polymerisation, the polymer is the only product of the reaction.

This means that the repeating unit has exactly the same atoms as the monomer.

37
Q

How do we name polymers

A

Start with ‘poly’ and then put brackets around the name of the monomer.

38
Q

When ethene monomers undergo addition polymerisation ?

A

poly(ethene) is the product

39
Q

When propene monomers undergo addition polymerisation, what is the product ?

A

poly(propene) is the product.

40
Q

When tetrafluoroethene monomers undergo addition polymerisation, what is the product ?

A

poly(tetrafluoroethene) is the product.

Poly(tetrafluoroethene) is known as PTFE

41
Q

When chloroethene monomers undergo addition polymerisation, what is the product ?

A

poly(chloroethene) is the product.

Poly(chloroethene) is also known as PVC.

42
Q

What happens in condensation polymerisation ?

A

Condensation polymerisation describes the joining together of monomers with 2 functional groups to produce larger polymers, as well as small molecule by-products (e.g. H2O).

43
Q

How is the simplest type of condensation produced ?

A

by combining 2 monomers that each have 2 identical functional groups.

E.g. Ethanediol + hexanedioic acid → Terylene + water

44
Q

How many functioal groups do monomers in condensation polymerisation have ?

A

2

45
Q

Why can Polymers cause many wastage problems ?

A

because they do not biodegrade (break down naturally).

46
Q

What are the problems with polymers ?

A

Landfill sites
Combustion
Difficult to recycle
Expensive

47
Q

How are landfill sites created ?

A

When plastics are added to a landfill site, the land becomes polluted.

We have to make new sites to bury plastics all the time.

48
Q

How is combustion a problem for polymers ?

A

When we combust (burn) plastics to generate energy, many toxic and acidic gases are released into our atmosphere.

For example, carbon dioxide is produced, which contributes to global warming.

49
Q

Why are polymers difficult to recycle ?

A

Plastics can be difficult to recycle. There are many types of plastic and, before they can be recycled, they must be sorted in to their different types.

Once they are sorted, they can be melted down and reshaped

50
Q

What are the financial problems of polymers ?

A

All expensive

51
Q

Why are plastics harmful ?

A

They can pollute our oceans

52
Q

What are the advantages of sythetic polymers ?

A

Synthetic polymers are made from crude oil, which is a finite resource. So by recycling, we reduce the amount of crude oil being used.

Synthetic polymers release energy when they are burned. This energy can be used to heat homes or generate electricity.

They are non-biodegradable, so last a long time and do not rot away. Recycling them means less space is used up in landfill sites

53
Q

What are the disadvantages of sythetic polymers ?

A

Burning synthetic polymers can release toxic gases into the atmosphere, such as carbon dioxide.

Sorting and recycling different plastics are expensive processes.

54
Q

What are sythetic plastics made from ?

A

Crude oil

55
Q

Whats are examples of Polymers that occur in nature and can be extracted ?

A

DNA
Starch
Cellulose
Proteins

56
Q

What is DNA ?

A

a polymer made from four different monomers called nucleotides.

57
Q

What are the monomers that combine to give starch and cellulose ?

A

Sugar

58
Q

What are the monomers that combine to give proteins ?

A

Amino acids

59
Q

What type of molecule are starch and cellulose?

A

Carbohydrates

GCSE Chemistry (10 decks)

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