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Chemistry > Book 1 -Oils, Earth And Atmosphere > Flashcards

Book 1 -Oils, Earth And Atmosphere Flashcards

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1
Q

What is crude oil?

A

Is an oil which is a mixture of mainly hydrocarbons, most of which are alkanes.

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2
Q

Describe the process of cracking?

A

Cracking involves the breaking covalent bonds. Hydrocarbons are heated to turn them into gases and are then passed over a long hot catalyst (a chemical to speed up a reaction). Cracking is a thermal decomposition process.

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3
Q

What are alkanes?

A

Saturated hydrocarbons that only have single bonds between the carbon atoms.

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4
Q

What are alkenes?

A

Unsaturated hydrocarbons that contain one or more double bonds between the carbon atoms.

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5
Q

How do you test if a substance is alkane or alkene?

A

Bromine water turns colourless when it reacts with unsaturated hydrocarbons (Alkene) but stays orange if it is added to saturated hydrocarbons (Alkanes) because there is no reaction.

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6
Q

Why is cracking important?

A

Some fractions of crude oil are in more demand (petrol) whereas some are in less demand (fuel oil). This problem is solved by cracking, to turn the large less useful fractions into smaller ore useful molecules.

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7
Q

What is a hydrocarbon?

A

A molecules made up from hydrogen and carbon only.

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8
Q

What type of reaction is cracking and why?

A

A thermal decomposition reaction in which molecules are broken down by heating them. This is because much energy is needed to break the covalent bonds between the atoms.

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9
Q

Once cracking has taking place, what are the short chain alkanes used for?

A

Fuels such as petrol.

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10
Q

Once cracking has taking place, what are the short chain alkenes used for?

A

Used to make plastic.

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11
Q

What is the general formula for alkanes?

A

CnH2n+2

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12
Q

What is the general formula for alkenes?

A

CnH2n

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13
Q

What is a polymer?

A

Polymers are large molecules made from lots of small molecules joined together (monomers)

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14
Q

What is a monomer?

A

The small molecules that are subunits of polymers.

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15
Q

What is polymerisation?

A

Reaction in which short molecules (monomers) are joined together to make a polymer.

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16
Q

What are most polymers made from?

A

Alkenes

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17
Q

Why are many common polymers made from alkenes?

A

This is because their double bonds can be broken and used to join the molecule to another alkene molecule.

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18
Q

Why are polymers useful?

A

Different polymers have different properties and uses.

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19
Q

What are smart materials?

A

Materials whose properties change if their environment changes.

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20
Q

What are shape-memory polymers?

A

Polymers that revert back to their original shape when the temperature is hot enough.

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21
Q

What is cracking?

A

The process by which long chain hydrocarbons, usually alkanes, are broken up into shorter and more useful hydrocarbons, usually alkanes and alkenes.

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22
Q

Name two uses of shape-memory polymer?

A
  • Heat-shrink wrapping used for packaging

- Heat-shrink tubing used to cover bundles of electrical wires.

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23
Q

Name two examples of smart materials?

A
  • Plastic bowls and spoons for baby food that change colour if the food it too hot.
  • Light sensitive lenses for spectacles that darken in bright light.
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24
Q

What are hydrogels?

A

Are polymers that can absorb a lot of water and turn into gel.

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25
Q

Name three uses of hydrogels.

A
  • Used in nappies to absorb urine, to prevent nappy rash.
  • Used to make soft contact lenses.
  • Used in garden plant containers and hanging baskets. The hydrogel is mixed in with the compost which means that it absorbs lots of water keeping the plant alive for longer.
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26
Q

Other uses of polymers (3)

A
  • Waterproof coats that allow water vapour from sweat to escape while keeping the water out.
  • Polymers are used to fill cavities in teeth instead of metal alloys.
  • For packaging materials, some packages can change colour when the food in going off and some packaging prevents the growth of bacteria, which has extended shelf-life for some foods.
  • Wound dressings can now be made to include anti-bacterial barriers, hydrogels and waterproof but breathable films.
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27
Q

What are the three ways of disposing polymers?

A
  • Burial in landfill
  • Incineration
  • Recycling
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28
Q

How are most polymers disposed?

A

Buried in landfill sites.

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29
Q

What is a landfill site?

A

A place where rubbish is dumped and buried in pre-prepared areas.

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30
Q

What is the problem with discarding polymers in landfill sites?

A

Most polymers are not biodegradable which means that microorganisms cannot break them down, so they will not decompose.

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31
Q

What is incineration?

A

It is when polymers are burned in furnaces.

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32
Q

What are the advantages of landfill sites?

A

They are cheap and easy to control.

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33
Q

What are the disadvantages with landfill sites?

A

Most polymers do not biodegrade. Landfill sites take up lots of room and it is becoming difficult to find more places for landfill.

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34
Q

What are the advantages for incineration?

A

The polymers are destroyed very efficiently unlike landfill sites where they are left. The heat released can also be used to generate electricity.

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35
Q

What are the disadvantages of incineration?

A

Carbon dioxide is produced when the polymers are burned, which is a greenhouse gas contributing to global warming. Unless the conditions are controlled carefully to ensure there is enough oxygen in the air, toxic gases including carbon monoxide, hydrogen chloride and hydrogen cyanide can also be produced. Incinerators are also very expensive.

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36
Q

What is recycling?

A

Processing used materials so that they can be made into new products.

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37
Q

What are the advantages of recycling?

A

Less crude oil and energy are used in recycling polymers than in making them from the raw materials. Also recycling avoids the problems caused by burying or burning.

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38
Q

What are the disadvantages of recycling?

A

Polymers must separated into the different types to be recycled, which must be done by hand which is time consuming and expensive.

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39
Q

How are polymers recycled?

A

Polymers are often recycled by chopping up the polymer into pellets that can be melted and mounded into new products. These are called thermosoftening polymers.

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40
Q

What is ethanol?

A

Ethanol is the most common type of alcohol, found in alcoholic drinks.

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41
Q

What are the uses of ethanol?

A
  • Ethanol is used as solvent to make many common substances; detergents and medicine.
  • Can be used as a fuel
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42
Q

What are biofuel?

A

Fuels made from living sources such as plant matter.

43
Q

What are renewable raw materials?

A

A resource that can be replaced one it has been used. Therefore an non-renewable substance is something that once it has been used cannot be replaced.

44
Q

What are the two ways of making ethanol?

A

Fermentation of carbohydrates and the Reaction of ethane with steam.

45
Q

Compare the two ways of making ethene? (Fermentation of carbohydrates and the reaction of ethene with steam)

A
  • The fermentation process uses renewable resources whereas the reaction with ethene and steam doesn’t.
  • Fermentation temperature is 30-40 degrees Celsius and at a normal pressure whereas the reaction needs 300 degrees Celsius and a high pressure
  • The type of process for fermentation is a batch process in comparison to a continuous process.
  • Fermentation is a slow reaction whereas the reaction is fast.
  • Fermentation creates impure ethanol whereas the reaction creates pure.
  • Fermentation is sustainable whereas the reaction is not.
46
Q

Compare the economic factors of fermentation and the reaction of ethene with steam.

A

Fermentation is a cheaper process, the main cost is the energy needed to separate the ethanol by fractional distillation. The reaction with steam is more expensive due to high temperatures and pressure.

47
Q

Compare the environmental factors of fermentation and the reaction of ethene with steam.

A

Fermentation uses renewable raw materials and less energy. The reaction uses non-renewable raw materials and more energy.

48
Q

What is hydration?

A

A chemical reaction involving the addition of water to a compound, for example the hydration of ethene to ethanol.

49
Q

Describe the process of fermentation.

A

Yeast and water are added to the source of carbohydrate and the mixture is left, in the absence of air. Fermentation then takes place.

50
Q

Describe the process of the reaction of ethene with steam.

A

The reaction of ethene and steam creates ethanol in a hydration reaction.

51
Q

What does immiscible mean?

A

Liquids that cannot dissolve into one another.

52
Q

What do you call two substances that do not mix?

A

Immiscible

53
Q

What is an emulsion?

A

Mixture of two immiscible liquids, in which tiny droplets of one liquid are distributed evenly through the other liquid.

54
Q

What is an emulsifier?

A

Substances added to an emulsion of two liquids that do not mix to stabilise it, to stop them from separating.

55
Q

Examples of emulsion.

A

Milk, butter, cream, salad cream, mayonnaise, make up and paint.

56
Q

Name a natural emulsifier.

A

Lecithin (from egg yolk)

57
Q

What two properties do emulsifiers have?

A

Hydrophobic and hydrophilic ends.

58
Q

What does hydrophobic mean?

A

Water hating

59
Q

What does hydrophilic mean?

A

Water loving end

60
Q

How does an emulsifier work?

A

The emulsifier has a hydrophobic (water hating) tail and a hydrophilic (water loving) head. This means the the hydrophilic head is attracted to the water, whereas the hydrophobic tail stays in the other substance as it hates the water. Together these forces act against each other holding the substance together, acting as an emulsifier.

61
Q

Why are emulsions used?

A

They are thicker and more viscous which can be desirable in for certain foods, paint and make up.

62
Q

What are the main sources of vegetable oils?

A

Nuts - from hazel bushes, fruit from oil palms and olive trees.
Seeds - from rapeseed plants and sunflowers.

63
Q

How are oils most commonly extracted?

A

After harvesting, the plant material sieved to remove stones and other objects that might damage the machinery. It is then crushed to break open the oil-containing cells, forming a mixture of oil and broken plant material. The oil can then be separated from the broken plant material by squashing or pressing the mixture. Oil and water are released. They separate into two separate layers. The water is drained away leaving the oil behind. It is then filtered to get rid of impurities an heated to kill bacteria and drive off any remaining water.

64
Q

Describe another less common way to extract vegetable oils?

A

By using a solvent. They dissolve in the solvent to form a solution that is more easily removed from the broken plant material. The solvent is distilled from the mixture leaving the oil behind.

65
Q

What is biodiesel?

A

Biodiesel is a biofuel made from vegetable oils such as rapeseed oil.

66
Q

How is the oil converted into biodiesel?

A

By reacting it with methanol and sodium and hydroxide.

67
Q

Why is biodiesel good for the environment?

A

A vehicle running o biodiesel will produce fewer particulates, less carbon monoxide and very little sulphur.

68
Q

Why is biodiesel not a carbon-neutral fuel?

A

Although no carbon dioxide is produced. To create the fuel, fossil fuels must be burnt.

69
Q

Describe the bonds between saturated vegetable oils?

A

The carbon atoms in their chains are joined to each other by single chemical bonds. This makes the chains flexible, so they can line up closely next to each other. As a result the attractive forces between individual molecules are relatively strong and a lot of energy is needed to overcome them. This means that the melting point of saturated fats tends to be high making them solid at room temperature.

70
Q

Describe the bonds between unsaturated vegetable oils?

A

Some of their carbons atoms are joined by double bonds instead of single bonds. These double bonds can put a rigid bend in a carbon chain. Bent chains cannot line up as closely as unbent chains. As a result, the attractive forces between individual molecules are relatively weak and molecules are easily moved apart. This means that the melting point of unsaturated oils tends to be low, making them liquids at room temperature.

71
Q

Are most vegetable oils saturated or unsaturated?

A

Unsaturated

72
Q

Are most animal fats saturated or unsaturated?

A

Saturated

73
Q

How do you test if the oil is saturated or unsaturated?

A

The presence of double bonds (unsaturated) can be detected using bromine.

74
Q

What is hardening?

A

Changing an unsaturated oil into a saturated fat by reaction with hydrogen.

75
Q

Describe the hardening process?

A

Vegetable oils are hardened by warming them to about 60 degrees Celsius and bubbling hydrogen gas through them. One of the double carbon bonds breaks and so does the single hydrogen bond in a hydrogen molecule. Then each of the two carbon atoms makes a new bond with a hydrogen atom.

76
Q

What type of reaction is the hardening process and what does it mean?

A

The sort of reaction is a hydrogenation reaction. This is a chemical reaction in which hydrogen is added to a compound. For example the hydrogenation of unsaturated oils to make saturated fats.

77
Q

Why do chemists do hardening?

A

To convert cheap unsaturated vegetable oils into solid fats.

78
Q

Why are hydrogenated vegetable oils helpful?

A

They can be used by vegetarians for cooking but have the same affect as animal fats.

79
Q

What are the advantage of cooking with vegetable oils?

A

Vegetable oils have higher boiling points, so food can be fried at higher temperatures meaning the food will be fried quicker. Also vegetable oils provide a pleasant flavour which water doesn’t. They are important in our diet because they provide energy and nutrients.

80
Q

What are the disadvantages of cooking with vegetable oils?

A

Vegetable oils due to their pleasant flavour may encourage people to over eat and too much fried and fatty food may make you overweight.

81
Q

What is the structure of the earth from inside to out?

A

Inner core, outer core, mantle and crust.

82
Q

What part of the earth do we get our minerals from?

A

The crust, the atmosphere and the oceans.

83
Q

How can the gases in the air be separated?

A

By fractional distillation because they have different boiling points.

84
Q

Why was Wegner’s theory initially rejected?

A
  • No evidence at the time.
  • Theory of land bridge was more popular.
  • Present day animals not similar on different continents.
85
Q

Why is an increase in levels of atmospheric carbon dioxide harmful for marine life?

A

Carbon dioxide dissolves in the oceans making them more acidic.

86
Q

What is a tectonic plate?

A

Section of the earth’s crust.

87
Q

Explain why the plates move?

A

Radioactive decay in the core releases heat that is transferred into the mantle and causes convection currents.

88
Q

What did the Miller-Urey experiment show?

A

That amino acids could be formed from the interaction of hydrocarbons and ammonia with lighting.

89
Q

What evidence is there that the plates are moving?

A

Sea floor is spreading

90
Q

How did the Earth’s early oceans form?

A

As the earth cooled, the water vapour in the atmosphere condensed.

91
Q

Why is there so little carbon dioxide in today’s atmosphere?

A

Most of it is dissolved in the oceans or trapped sedimentary rock as carbonates or fossil fuels.

92
Q

What was the responsible for the composition of the Earth’s early atmosphere?

A

Volcanic eruptions

93
Q

Explain the differences in the amount of carbon dioxide in the early atmosphere compared today.

A

Plants photosynthesised using up carbon dioxide while producing oxygen which decreased the carbon dioxide levels and increased the oxygen levels.

94
Q

Why do earthquakes and volcanic eruptions happen?

A

Sudden movements at plate boundaries.

95
Q

Percentage of gases to show the earth’s composition of the atmosphere today.

A

Oxygen 20%, Nitrogen 80%, Trace gases 1% and Carbon dioxide 0.003%.

96
Q

Give 2 pieces of evidence that supports Wegner’s theory.

A
  • Land masses on different continents have coastlines that fit together.
  • Similar fossils found on different continents.
97
Q

Where do earthquakes and volcanoes occur?

A

At plate boundaries between tectonic plates.

98
Q

What are the warning signs before an earthquake?

A
  • increased seismic activity
  • water levels fall
  • some animals acts strangely.
99
Q

What are the warning signs before a volcanic eruption?

A
  • increasing temperature of the volcano due to magma moving underground
  • rising ground level due to build up of magma
  • more sulphur dioxide gas given out
100
Q

Why is the amount of carbon dioxide in our atmosphere beginning to rise?

A

Global warming

101
Q

Scientist believe that earth used to be like which planets?

A

Venus and Mars

102
Q

Why is ethanol a renewable energy resource?

A

The sugar used to make it is from plants.

103
Q

Why does hydrogen not cause pollution?

A

The only waste product is water vapour.

Chemistry (4 decks)

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