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Chemistry 21st century > Chemicals in our lives > Flashcards

Chemicals in our lives Flashcards

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1
Q

Who studies rocks?

A

Geologists

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2
Q

What do geologists learn from rocks?

A

How rocks form, how they change, how and when changes happen.

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3
Q

What are the chunks of the earth’s crust that move called?

A

Tectonic plates

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4
Q

How do tectonic plates interact?

A

Slide past each other, collide or pull apart

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5
Q

What builds mountains?

A

Plate collisions.

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6
Q

How can geologists explain the past history of the earth?

A

By observing what happens today and assuming that would have happened in the past.

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7
Q

Has Britain always been where it is now (on the earth’s globe)?

A

No, it has drifted over the years.

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8
Q

Where was Britain 600 million years ago?

A

Near the south pole - and we had an ocean between England and Scotland

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9
Q

What happened to the different continents as the drifted?

A

They all crashed together to form a supercontinent

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10
Q

What was the supercontinent called?

A

Pangea

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11
Q

What sort of rock is formed when lava cools?

A

Igneous.

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12
Q

What happens to the magnetic materials in lava in the earth’s magnetic field?

A

They line up with the magnetic field.

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13
Q

What happens to the magnetic field of the earth over time?

A

It changes.

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14
Q

How do igneous rocks support the theory of continental drift?

A

The magnetic fields are not lined up with the current poles, and show slow progression over time.

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15
Q

What are rocks, from an industrial point of view?

A

Raw materials buried in the ground.

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16
Q

Give some examples of rocks used as raw materials.

A

Coal, salt, limestone. (Salt = NaCl, limestone = CaCO3)

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17
Q

How is limestone formed?

A

Sea creatures die and their skeletons form sediment. Sedimentary rocks form, pushed to the surface by plate tectonic movements.

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18
Q

How is coal formed?

A

Trees and other plants die and are covered by a swamp, where the low oxygen makes decay very slow. Pressure eventually makes coal.

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19
Q

How are salt deposits formed?

A

Rivers wash it to the sea or lakes, then evaporation leaves it behind, it gets buried by other sediments.

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20
Q

Salt is found in Cheshire. What does this tell you about the history of Cheshire?

A

It was covered by a shallow sea.

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21
Q

What evidence is there for our theory of how coal is formed?

A

Fossils of plants found in coal

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22
Q

What evidence is there for our theory of how limestone is formed?

A

Limestone contains bits of sea creatures and shells.

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23
Q

What evidence is there for our theory of rock salt formation?

A

Rock salt contains different shaped grains that show water erosion and wind erosion.

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24
Q

What is salt used for?

A

The food industry; as a source of chemicals (sodium and chlorine); to put on roads in winter.

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25
Q

How can we obtain salt?

A

Evaporation of sea water; mining salt deposits.

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26
Q

What is the chemical formula for salt?

A

NaCl

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27
Q

Why is rock salt used for spreading on roads?

A

Sand in rock salt gives grip; sand is easily visible so it is easy to see where the salt is; salt in solution lowers the freezing point of water.

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28
Q

How many rock salt mines in the UK?

A

One, in Cheshire.

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29
Q

Where would you choose to extract salt from sea water?

A

In hot countries, it is not economical in the UK

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30
Q

What could happen if you extract all the salt in a specific part of the mine?

A

Subsidence

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31
Q

What can be done to reduce the risk of subsidence?

A

Leave salt behind to hold the rocks up - about half is currently left.

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32
Q

How, other than digging, can salt be mined?

A

Solution mining

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33
Q

How does solution mining work?

A

Pump high pressure water into the mine, it dissolves the salt and brine comes up.

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34
Q

What is the advantage of solution mining?

A

automatic; leaves the sand behind and produces purer salt

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35
Q

What is the risk of mining salt?

A

If water gets into the mine it can dissolve salt and that could contaminate the water supply

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36
Q

Why is salt added to food?

A

flavour; preserves food

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37
Q

How does salt preserve food?

A

It draws water out of living things by osmosis.

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38
Q

What are the health implications of too much salt?

A

It is bad for health.

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39
Q

What health problems can salt cause?

A

high blood pressure; heart failure; strokes

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40
Q

What is salt classified as?

A

A hazard.

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41
Q

What is the (health) definition of risk?

A

The chance of getting ill, and the consequence if you did.

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42
Q

How can the risk associated with eating salt be estimated?

A

By measuring salt intake.

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43
Q

How can you know how much salt is in a food product?

A

The label has to show how much salt is in it.

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44
Q

What does knowing the risk allow you to do?

A

Make informed decisions.

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45
Q

What is the word equation for neutralisation?

A

Acid + base => salt + water

46
Q

What is an alkali?

A

A soluble base, which has to have a pH of over 7

47
Q

What are alkalis used for in industry?

A

Dyeing cloth; neutralising acid soil; making soap; making glass

48
Q

What was used as an early alkali?

A

Stale urine, ashes from burning wood.

49
Q

What was the first alkali to be manufactured?

A

lime - Calcium oxide, CaO

50
Q

How was Calcium Oxide produced?

A

Heating limestone (Calcium carbonate)

51
Q

What is the chemical equation for heating limestone?

A

CaCO3 => CaO + CO2

52
Q

Who discovered a way of making sodium carbonate?

A

Leblanc

53
Q

What is the Leblanc process?

A

Heating salt and limestone

54
Q

What by-products does the Leblanc process make?

A

Hydrogen chloride ( HCl), and solid waste that released hydrogen sulfide

55
Q

What is the HCl used for now?

A

Making hydrochloric acid; making chlorine

56
Q

How can you make chlorine?

A

By reacting manganese dioxide and hydrochloric acid

57
Q

Name some alkalis

A

NaOH, KOH, Ca(OH)2, Na2CO3

58
Q

What happens when a metal hydroxide reacts with acid?

A

hydroxide + acid => salt +water

59
Q

What happens when a metal carbonate reacts with acid?

A

carbonate + acid => salt + water + CO2

60
Q

What happens when you react Ionium hydroxide with Gabic acid?

A

hydroxide + acid => salt and water. In this case, the salt would be Ionium gabate.

61
Q

Why is chlorine added to drinking water?

A

To kill microorganisms

62
Q

Before chlorination of drinking water, what happened to people drinking the water?

A

Many died.

63
Q

What exists between the start of water chlorination in the US and a fall in death rates from typhoid?

A

A correlation

64
Q

What is chlorine?

A

A toxic gas. Group 7, very reactive.

65
Q

What would happen if too much chlorine were added to the drinking water?

A

It would affect human health. Chlorine was used to “gas” soldiers in WW I

66
Q

What choice do you have about chlorine in the mains water?

A

None, but you could drink bottled water or use a carbon filter to remove it (like our fridge)

67
Q

Why are people worried about chlorine in the drinking water?

A

It can react with organic materials in the water supply to form toxic/carcinogenic compounds called disinfectant by-products

68
Q

What is electrolysis?

A

Breaking up a compound by use of an electric current

69
Q

What are the products of the electrolysis of brine?

A

Hydrogen (H2) ; Chlorine (Cl2); Sodium Hydroxide (NaOH)

70
Q

Which electrode is the cathode?

A

The negative electrode - so it attracts the cations, the positive ions.

71
Q

Which electrode is the anode?

A

The positive electrode - so it attracts the anions, the negative ions.

72
Q

Why is electrolysis expensive?

A

It uses a lot of electricity.

73
Q

Why are the advantages of the electrolysis of brine?

A

Cheap raw material; all the products are useful

74
Q

What is brine?

A

Sodium chloride in solution.

75
Q

When brine is electrolysed, what forms at the cathode?

A

Hydrogen (H2)

76
Q

When brine is electrolysed, what forms at the anode?

A

Chlorine (Cl2)

77
Q

What colour would sodium hydroxide solution turn litmus paper?

A

Blue or violet - it is alkaline

78
Q

What is the industrial use of chlorine?

A

Plastics such as PVC (polyvinylchloride), in medicine, crop protection

79
Q

What is the industrial use of hydrogen?

A

Making margarine and other hydrogenated fats (bad for health!); rocket fuel; fuel cells in cars being worked on

80
Q

What is the industrial use of sodium hydroxide?

A

Paper recycling; industrial cleaners (and domestic drain unblockers); aluminium refining.

81
Q

Why is brine electrolysis such a widely used industrial process, despite the cost of the electricity?

A

It produces three chemicals that are very useful, and common salt and water are cheap.

82
Q

Why have some chlorine products been banned from fridges?

A

They damage the ozone layer - CFCs - no longer permitted in fridges.

83
Q

Why is chlorine being used to bleach paper a problem?

A

It produced dioxins, very dangerous chemicals that have been shown to increase the risk of cancer.

84
Q

Why would using a mercury diaphragm method to be able to do continuous electrolysis be a problem?

A

It releases mercury waste. Mercury salts build up in the tissues of living things, so mercury is a cumulative poison.

85
Q

What is the problem with plastics made using chlorine?

A

They are not biodegradable

86
Q

What do chemicals contain?

A

Elements.

87
Q

How can you destroy an element (chemistry)?

A

You can’t, so the elements stay in the environment forever.

88
Q

How do you work out how dangerous a substance is?

A

A risk assessment.

89
Q

What are the states of matter?

A

Solid; liquid; gas

90
Q

When toxic chemicals persist in the environment, what can happen?

A

They can be carried large distances, enter food chains, and build up in the tissues of living things.

91
Q

What do you need to know to decide the level of risk posed by a chemical?

A

How much is needed to cause harm; how much will be used; the chance of it being released into the environment; what the effects would be

92
Q

When were European laws passed making risk assessments compulsory for new chemicals?

A

30 years ago

93
Q

What risk assessments have been done on substances used before then?

A

Could be none.

94
Q

Why do people perceive new chemicals as more risky?

A

They have unfamiliar names, and people often assume that older substances will have been thoroughly tested by now, which may not be the case.

95
Q

What does PVC contain?

A

it is a polymer containing carbon, hydrogen and chlorine.

96
Q

Why are plasticisers added to PVC?

A

To soften it, to make it suitable for electrical cables and rain coats.

97
Q

What is the size of the plasticiser molecule?

A

Small

98
Q

What happens to the plasticisers over time?

A

They can leach out of the plastic, so old plastic is often very brittle.

99
Q

What are the safety worries about plasticiser molecules?

A

The plasticisers have been tested, but they may affect fish, and large amounts do harm animals.

100
Q

What has plasticised PVC been banned from being used for?

A

Children’s toys (Europe and USA) - fake toys may contain it.

101
Q

What does PVC give off when burned?

A

Toxic gases including dioxins

102
Q

What happens to dioxins?

A

If they enter the food chain they build up in fat and are thought to cause cancer.

103
Q

Why are people disputing the safety of plasticisers?

A

They are new, so no long-term safety tests have been conducted.

104
Q

What is an LCA?

A

A Life cycle assessment.

105
Q

What does an LCA measure?

A

The energy used to make, use and dispose of a substance.

106
Q

What are the 4 stages of an LCA?

A

Preparing the chemicals from raw materials; making the product, including transport; use of the product; disposing of the product when it is no longer used.

107
Q

What is considered at each stage of an LCA?

A

What resources required; how much energy needed (or produced); how much water and air used; how is the environment affected.

108
Q

What does doing LCAs enable you to do?

A

Compare different products fairly

109
Q

What do you need for an accurate LCA?

A

A lot of data!

110
Q

Why are some aspects of the LCA so hard to measure?

A

The use and disposal of a product can vary so much - a car may crash and be written off after one hour, or still be used 25 years later.

Chemistry 21st century (10 decks)

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