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10. Chemistry of the environment Flashcards

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1
Q

Where can sulfur be found in its elemental state?

A

Sulfur is found in its elemental state underground in the USA, Mexico and Poland

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2
Q

How can sulfur be obtained as a by product?

A

It is also a by-product from the removal of sulfur from petroleum and natural gas

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3
Q

In what ores can sulfur be found?

A

Sulfur can also be obtained from sulfide ores

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4
Q

What are the main uses of sulfur?

A
  • in making sulphuric acid
  • in making rubber tires more flexible (vulcanising)
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5
Q

Why is sulphuric acid important?

A

is a very important chemical used in many industries

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6
Q

What does vulcanising consist of?

A

the rubber tyre is heated with sulfur to make it more flexible

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7
Q

How can sulfur dioxide be made?

A

Sulfur dioxide can be made by the direct combination of sulphur with oxygen

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8
Q

What are 2 uses of sulfur dioxide?

A

As a bleach in the manufacture of wood pulp for paper

As a preservative for foods and drinks by killing bacteria

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9
Q

How are sulfites used?

A

Sulfites are often added to foods and these release sulfur dioxide in acidic conditions

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10
Q
  1. How can sulphuric acid be made?
    contact process
A

Sulfuric acid is synthesised by the Contact process

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11
Q
  1. What is used in the contact process?
    contact process
A

which use sulfur and oxygen from air

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12
Q
  1. how many stages does the contact process have?
    contact process
A

3

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13
Q
  1. What is the first stage?
    Give CE
    contact process
A

The first stage is the oxidation of sulfur:

S + O2 → SO2

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14
Q
  1. What is the second stage?
    Give CE
    contact process
A

The main stage is the oxidation of sulfur dioxide to sulfur trioxide

2SO2 + O2 ⇌2SO3

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15
Q
  1. What catalyst is used in the second stage?
    contact process
A

uses a V2O5 catalyst

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16
Q
  1. In which stage do the conditions need to be considered?
    contact process
A

The conditions for the main stage of production of sulfur trioxide need to be considered

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17
Q
  1. What temperature and pressure need to be kept in stage 2?
    contact process
A

Temperature - 450 degrees C

Pressure - 2 atm

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18
Q
  1. Why, in terms of equilibrium, is the temperature 450ºC?
    contact process
A

The reaction is exothermic, so increasing the temperature shifts the position of equilibrium to the left in the direction of the reactants

Therefore the higher the temperature, the lower the yield of sulfur trioxide

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19
Q
  1. What is 450ºC a compromise between?
    contact process
A

The optimum temperature is a compromise between a higher rate of reaction at a higher temperature and a lower equilibrium yield at a higher temperature

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20
Q
  1. Why, in terms of equilibrium, is the pressure 2atm?
    contact process
A

An increase in pressure shifts the position of equilibrium to the right in the direction of a smaller number of gaseous molecules

However the position of equilibrium lies far to the right (the equilibrium mixture contains about 96% sulfur trioxide)

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21
Q
  1. Why, in terms of manufacture, is the pressure 2atm?
    contact process
A

So the reaction is carried out at just above atmospheric pressure because:

a) it is not worth spending the extra energy or money required to produce high pressures
b) a higher pressure would increase the problems of dealing with the corrosive mixture of gases

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22
Q
  1. What is produced during stage 3?
    Give CE

contact process

A

Once stage 2 is completed, the sulfur trioxide is absorbed into a solution of 98% sulphuric acid to produce a thick liquid called oleum:

SO3 + H2SO4 → H2S2O7

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23
Q
  1. Why is the sulfur trioxide dissolved into sulphuric acid and not, for example, water?
    contact process
A

It is not absorbed into water because a fine mist of sulfuric acid would be produced and this would be difficult to condense and is also highly dangerous

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24
Q
  1. Why is the sulfur trioxide dissolved into sulphuric acid and not, for example, water?
    contact process
A

It is not absorbed into water because a fine mist of sulfuric acid would be produced and this would be difficult to condense and is also highly dangerous

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25
Q
  1. What is oleum then dissolved into?
    Give CE

contact process

A

Oleum is added to water to form concentrated sulfuric acid:

H2S2O7 + H2O → 2H2SO4

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26
Q

What type of acid is sulphuric acid?

A

Sulfuric acid is a strong dibasic acid

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27
Q

What is a dibasic acid?

A

two of its hydrogen atoms can be replaced by a metal

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28
Q

Give CE for reaction between zinc oxide and sulphuric acid

A

ZnO + H2SO4 → ZnSO4 + H2O

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29
Q

Give CE for reaction between magnesium and sulphuric acid

A

Mg + H2SO4 → MgSO4 + H2

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30
Q

Give CE for reaction between sodium carbonate and sulphuric acid?

A

Na2CO3 + H2SO4 → Na2SO4 + CO2 + H2O

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31
Q

What 3 properties does concentrated sulphuric acid have?

A

Concentrated sulphuric acid is corrosive, a powerful oxidising agent and a powerful dehydrating agent

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32
Q

What does it mean if sulphuric acid is a good dehydrating agent?

A

it is very good at removing water from other substances

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33
Q

What will happen when sugar is mixed with concentrated sulphuric acid?

A

For example, if mixed with sugar (C6H12O6), concentrated H2SO4 will remove water molecules and leave behind carbon in a spectacular looking reaction that produces a tower of pure carbon

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34
Q

What are 2 uses of dilute sulphuric acid?

A

Used as a catalyst in many organic reactions

Also used as to clean the surface of metals

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35
Q

What are 6 uses of concentrated sulphuric acid?

A

used in making:

phosphate fertilisers
soaps
detergents
acid drain cleaners
used in the production of paints and dyes

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36
Q

What are two chemical tests for water?

A

Cobalt (II) chloride: turns from blue to pink

Copper (II) sulfate: turns white to blue

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37
Q

What are two problems associated with lack of water?

A

Water used to irrigate crops - Crops cannot grow → lack of food for populations reliant on crops
No safe water for drinking: increased risk of disease

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38
Q

Describe the process of treatment of water supply (6)

A

Water passed through metal screens and filtered for twigs/leaves
In settlement tank, soil particles settle at bottom
Aluminum sulfate added to make small particles in water stick together. Particles fall to bottom of tank
Passed through filter made of sand and gravel, removes any insoluble particles not removed
Chlorine added to kill bacteria
pH of water adjusted, water run off

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39
Q

What are the uses of water in industry and in the home?

A

Generate electricity

Cooking, washing, cleaning

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40
Q

What is the composition of clean, dry air?

A

78% nitrogen, 21% oxygen and remainder: mixture of noble gases/carbon dioxide

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41
Q

Describe the separation of oxygen and nitrogen by fractional distillation (4)

A

Water + carbon dioxide removed from air
- Water by passing it through a drying agent
- carbon dioxide by reacting it with sodium hydroxide
Air is cooled to -23 degrees celcius and compressed
Cold compressed air allowed to expand in larger space, air cools when expand until temp. drops to -200 degrees celcius - air is liquid
- Argon, krypton and xenon are removed from oxygen by further distillation
When liquid air is warmed, nitrogen boils off first (lower boiling point) + condenses
Mixture fed to top column, oxygen condenses, nitrogen gas residue removed at top

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42
Q

What are the four common pollutants in the air?

A

carbon monoxide
sulfur dioxide
oxides of nitrogen
lead compounds

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43
Q

What are the sources + effects of carbon monoxide?

A

S:
incomplete combustion of carbon-containing substances
E:
reacts w/ haemoglobin, prevents from carrying oxygen, death

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44
Q

What are the sources + effects of sulfur dioxide?

A

S:
combustion of fossil fuels which contain sulfur compounds
E:
irritates eyes and throat, causes respiratory problems and acid rain

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45
Q

What are the sources + effects of oxides of nitrogen?

A

S:
car engines
denitrification
high temperature furnaces
E:
causes respiratory problems and acid rain

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46
Q

What are the sources + effects of lead compounds?

A

S:
burning of petrol
E:
causes damage to brain + nerve cells in young children

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47
Q

Describe the process of catalytic conversion of oxides of nitrogen in car engines (5)

A

Exhaust gases from car engine passed through a honeycomb (surface covered with metal catalysts) in a catalytic converter
Two compartments:
Compartment 1: metals catalyse conversion of nitrogen oxides to nitrogen
2NO(g) → N2(g) + O2(g)
2NO2(g) → N2(g) + 2O2(g)
Compartment 2: Carbon monoxide converted to carbon dioxide
2CO(g) + O2(g) → 2CO2(g)
Carbon monoxide may also react directly with nitrogen oxides (nitric acid + nitrogen dioxide)

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48
Q

What is needed for iron to rust?

A

Water and Oxygen

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49
Q

What are the four methods of rust prevention?

A

Paint
Plastic Coating
Galvanising
Sacrificial Protection

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50
Q

What is galvanising?

A

coating iron with zinc

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51
Q

What is sacrificial protection?

A

blocks of more reactive metal attached to iron surface

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52
Q

What are NPK fertilizers used for?

A

replace essential elements lost when plants are harvested

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53
Q

What causes the displacement of ammonia from its salts in soil?

A

Too much lime put in soil, displaces ammonia from ammonium salts, lost as gas

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54
Q

What is ammonia’s function in soil

A

To neutralise soil acidity

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55
Q

What is the Haber process?

A

Industrial manufacture of ammonia NH3

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56
Q

What is the equation for the Haber process?

A

N2 (g) + 3H2 (g) ⇌ 2NH3 (g)

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57
Q

What are the raw materials required for the Haber process?

A

Nitrogen: from the air

Hydrogen

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58
Q

What are the essential conditions required for the Haber process?

A

Temperature: 450°C
Pressure: 200 atm
Catalyst: Iron

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59
Q

How does methane cause global warming?

A

Absorb heat energy and prevent it escaping into space - global warming

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60
Q

How does carbon dioxide cause global warming?

A

heat is absorbed by carbon dioxide and becomes trapped within the Earth’s atmosphere → Earth becomes hotter

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61
Q

What are the three ways carbon dioxide is formed?

A

Product of complete combustion of carbon containing substances
Product of respiration
Production of reaction between an acid and a carbonate

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62
Q

What is the function of the carbon cycle?

A

keeps concentration of carbon dioxide in atmosphere constant

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63
Q

What are the three main processes in the carbon cycle?

A

combustion, respiration, photosynthesis

64
Q

What is the equation for testing of water? (copper sulfate)

A

CuSO4(s) + 5H2O => CuSO4.5H2O(s)

65
Q

What is the equation for testing of water? (cobalt (II) chloride)

A

CoCl2 (s) + 6H2O (l) => CoCl2.6H2O

66
Q

Q
What is the equation for testing of water? (cobalt (II) chloride)

A

CoCl2 (s) + 6H2O (l) => CoCl2.6H2O

67
Q

Is treated water pure?

A

No

68
Q

What are the two oxides of nitrogen formed in internal combustion engines?

A

Nitric oxide: N2 + O2 → 2NO(g)

Nitrogen oxide: N2 + 2O2 → 2NO2(g)

69
Q

Why do oxides of nitrogen form in internal combustion engines?

A

Due to the high temperature and pressure inside an internal combustion engine which causes nitrogen and oxygen to combine

70
Q

What are the sources of sulfur? (4)

A

Found as an element, in large underground beds
Found around the rims of volcanoes.
It occurs in metal ores
e.g. lead sulphide
Sulphur compounds also occur naturally in the fossil fuels
e.g. coal

71
Q

What are the uses of sulfur? (2)

A

In car batteries as electrolyte

In manufacture of sulphuric acid (through Contact process)

72
Q

What are the uses of sulfur dioxide? (2)

A

Manufacture of sulphuric acid
As a food preserver; kills bacteria
As a bleach in the manufacture of wood pulp for paper

73
Q

Describe the Contact Process (4)

A

Sulphur is first burned in air producing sulphur dioxide
It is then mixed with more air and passed over four separate beds of catalyst, Vanadium (V) oxide, at 450°C to form sulphur trioxide
It is then dissolved in concentrated sulphuric acid forming a thick fuming liquid called oleum
It is then mixed carefully with water to form concentrated sulphuric acid

74
Q

What are the conditions required for the Contact Process? (3)

A

Catalyst: Vanadium (V) oxide
Temperature: 450°C
Pressure: 2atm

75
Q

What are the uses of concentrated sulfuric acid? (3)

A

for making detergents
as a catalyst
as a dehydrating agent

76
Q

What are the uses of diluted sulfuric acid? (4)

A

For making fertilizers.
To treat metals to remove oxidisation before painting.
For anodising aluminium.
As an acid in car batteries.
For manufacturing paints, dyes and fibres.
As a common laboratory reagent

77
Q

What are the features of concentrated sulfuric acid? (3)

A

powerful dehydrating agent: take water from many substances
Used to dry gases (except ammonia)
Powerful oxidising agent

78
Q

What are the features of dilute sulfuric acid? (2)

A

typical strong dibasic acid: two replaceable hydrogen atoms may produce 2 series of salts – normal and acid salts

79
Q

What is the catalyst in the contact process?

A

Vanadium (V) oxide

80
Q

What temperature is used in the contact process?

A

450°C

81
Q

What pressure is used in the contact process?

A

2atm

82
Q

Why do we want to form oleum in the Contact Process?

A

When sulfur trioxide reacts with water, a fine mist of sulfuric acid forms which does not condense easily.

83
Q

What does an increase in temperature lead to and why?

A

Reaction is exothermic
=> yield of sulfur trioxide decreases with increasing temp.
Too low temp, rate of reaction low => compromise

84
Q

What is the effect of the catalyst on the equilibrium?

A

Nothing - catalyst works equally

85
Q

Write equations involved in Contact Process?

A

S + O2 → SO2
2SO2 + O2 ⇌2SO3
SO3 + H2SO4 → H2S2O7
H2S2O7 + H2O → 2H2SO4

86
Q

Write equations involved in Contact Process?

A
87
Q

Describe chemical tests for the presence of
water using anhydrous cobalt(II) chloride and
anhydrous copper(II) sulfate

A

Anhydrous cobalt(II) chloride and anhydrous copper(II) sulfate are used as chemical indicators to test for the presence of water.

When these indicators are dry, they have a particular color. However, in the presence of water, they undergo a chemical reaction and change color.

Anhydrous cobalt(II) chloride: When anhydrous cobalt(II) chloride is dry, it is blue in color. However, in the presence of water, it reacts to form hydrated cobalt(II) chloride, which is pink in color. Therefore, anhydrous cobalt(II) chloride can be used to test for the presence of water by observing whether the blue color changes to pink in the presence of a sample suspected to contain water.

88
Q

Describe chemical tests for the presence of
water using anhydrous copper(II) sulfate

A

Anhydrous cobalt(II) chloride and anhydrous copper(II) sulfate are used as chemical indicators to test for the presence of water.

When these indicators are dry, they have a particular color. However, in the presence of water, they undergo a chemical reaction and change color.
Anhydrous copper(II) sulfate: When anhydrous copper(II) sulfate is dry, it is white in color. In the presence of water, it reacts to form hydrated copper(II) sulfate, which is blue in color. Therefore, anhydrous copper(II) sulfate can be used to test for the presence of water by observing whether the white powder turns blue in the presence of a sample suspected to contain water.

89
Q

Describe how to test for the purity of water using
melting point and boiling point

A

Melting point:
a. Take a clean and dry test tube, and fill it up to around 1/3 with the water to be tested.
b. Insert a thermometer into the tube, ensuring that it does not touch the sides or bottom of the tube.
c. Place the test tube in an ice-water bath, and stir the thermometer until the temperature stabilizes.
d. Note the temperature at which the water starts freezing (when ice crystals begin to form).

90
Q

Describe how to test for the purity of water using
boiling point

A

Boiling point:
a. Take a clean and dry boiling tube, and fill it up to around 1/3 with the water to be tested.
b. Insert a thermometer into the tube, ensuring that it does not touch the bottom of the tube.
c. Heat the water slowly, while stirring the thermometer.
d. Note the temperature at which the water starts boiling (when bubbles form and rise to the surface).

91
Q

How can we know if water is pure or not using mp and bp?

A
92
Q

Why is distilled water is used in practical
chemistry rather than tap water

A

Distilled water is used in practical chemistry rather than tap water because it contains fewer chemical impurities.

Tap water is obtained from natural sources such as rivers, lakes, or groundwater, and may contain various chemical impurities such as minerals, organic matter, and other contaminants that can interfere with chemical reactions or affect the accuracy of measurements. Even after treatment by water treatment plants, tap water can still contain some impurities that can affect experimental results.

Distilled water, on the other hand, is produced by boiling water and collecting the steam, which is then condensed to form pure water. This process removes most impurities, including minerals, organic matter, and other contaminants, resulting in water that is free of chemical impurities.

Since distilled water is free of chemical impurities, it is the preferred choice for many chemical experiments as it ensures the accuracy and reproducibility of results.

93
Q

What substances may come from natural sources that water can contain?

A

dissolved oxygen
metal compounds
plastics
sewage
harmful microbes
nitrates from fertilisers
phosphates from fertilisers and detergents

94
Q

State a substance that may come from natural sources that are in water that can be beneficial

A

dissolved oxygen
metal compounds

95
Q

why can metal compounds be beneficial

A

they can provide essential minerals for life

96
Q

why can dissolved oxygen be beneficial for?

A

aquatic life

97
Q

what are the possible harmful effect of metal compounds?

A

they’re toxic

98
Q

what are the possible harmful effect of plastics?

A

harm in aquatic life

99
Q

what are the possible harmful effects of sewage?

A

contains harmful microbes which
cause disease

100
Q

what are the possible harmful effects of nitrates and phosphates?

A

nitrates and phosphates lead to
deoxygenation of water and damage to
aquatic life

101
Q

Describe the treatment of the domestic water

A

(a) Sedimentation and filtration: In this stage, the water is allowed to settle to remove large particles and sediments. The settled water is then passed through a filter bed to remove any remaining suspended solids and impurities. This process removes the majority of impurities, including sand, silt, and other suspended solids.

(b) Use of carbon to remove tastes and odours: After the filtration stage, the water is passed through a bed of activated carbon, which removes any remaining impurities, including organic matter, chlorine, and other chemicals that can affect the taste and odor of the water.

(c) Chlorination to kill microbes: After the carbon filtration stage, the water is treated with chlorine to kill any remaining bacteria, viruses, and other harmful microbes that may be present in the water. Chlorine is an effective disinfectant that kills a wide range of pathogens, and it is commonly used in water treatment to ensure the safety of the water supply.

Overall, the treatment of domestic water supply involves a series of processes that are designed to remove impurities and ensure that the water is safe for human consumption. These processes may vary depending on the quality of the source water and the specific requirements of the water supply system, but they typically involve sedimentation and filtration, carbon treatment, and chlorination to remove impurities, improve taste and odor, and kill harmful pathogens.

102
Q

what compounds are used as fertilizers?

A

ammonium salts and nitrates

103
Q

Describe the use of NPK fertilisers to provide the
elements nitrogen, phosphorus and potassium
for improved plant growth

A

NPK fertilizers are a type of fertilizers that contain the essential plant nutrients nitrogen (N), phosphorus (P), and potassium (K). These nutrients are required by plants for healthy growth and development, and deficiencies can result in stunted growth, poor yields, and other problems.

Nitrogen is required for the formation of proteins, nucleic acids, and chlorophyll, which are essential components of plant cells. Phosphorus is required for energy transfer and the formation of DNA and cell membranes, while potassium plays a role in the regulation of water uptake and other important plant processes.

NPK fertilizers are formulated to provide these essential nutrients in the correct proportions for optimal plant growth. The exact formulation of the fertilizer will depend on the specific requirements of the crop and the soil conditions, but a typical NPK fertilizer might contain around 10% nitrogen, 5% phosphorus, and 10% potassium.

The application of NPK fertilizers can help to improve plant growth and yield by providing the essential nutrients that the plants need. However, it is important to use these fertilizers carefully, as over-application can lead to environmental problems such as pollution of waterways and eutrophication.

Overall, the use of NPK fertilizers is an important tool for improving plant growth and ensuring healthy crops, but it must be used judiciously and with careful consideration of the specific needs of the plants and the environmental impacts of fertilizer use

104
Q

State the composition of clean air

A

78% nitrogen, N2, 21% oxygen, O2
and the remainder as a mixture of noble gases
and carbon dioxide, CO2

105
Q

what is the source of CO2?

A

carbon dioxide from the complete
combustion of carbon-containing fuels

106
Q

what is the source of methane?

A

methane from the decomposition of
vegetation and waste gases from digestion in
animals

107
Q

what is the source of oxides?

A

oxides of nitrogen from car engines

108
Q

what is the source of sulfur dioxide?

A

sulfur dioxide from the combustion of fossil
fuels which contain sulfur compounds

109
Q

what are the adverse effects of CO2?

A

higher levels of carbon dioxide leading to increased global warming, which leads to climate change

110
Q

what are the adverse effects of carbon monoxide?

A

toxic gas

111
Q

what are the adverse effects of particulates?

A

increased risk of respiratory problems and cancer

112
Q

what are the adverse effects of oxides?

A

acid rain, photochemical
smog and respiratory problems

113
Q

what are the adverse effects of methane?

A

higher levels of methane leading
to increased global warming, which leads to
climate change

114
Q

what are the adverse effects of sulfur dioxide?

A

acid rain

115
Q

Describe how the greenhouse gases carbon
dioxide and methane cause global warming

A

Carbon dioxide (CO2) and methane (CH4) are greenhouse gases that contribute to global warming by trapping heat in the Earth’s atmosphere. They do this by absorbing and re-emitting thermal energy, which is radiated from the Earth’s surface as heat.

When solar radiation enters the Earth’s atmosphere, some of it is absorbed by the Earth’s surface and some is reflected back into space. However, greenhouse gases like CO2 and CH4 absorb and re-emit some of this thermal energy back towards the Earth’s surface, reducing the amount of thermal energy that is lost to space. This leads to an increase in the Earth’s average temperature, known as global warming.

Carbon dioxide is particularly important in this process because it is the most abundant greenhouse gas and has a long atmospheric lifetime. When CO2 is released into the atmosphere through human activities such as burning fossil fuels or deforestation, it can remain in the atmosphere for hundreds of years, continuing to trap heat and contribute to global warming.

Methane, on the other hand, is a much less abundant greenhouse gas but is more effective at trapping heat than CO2. Methane is produced by natural processes such as the decomposition of organic matter in wetlands, as well as by human activities such as agriculture and the production of fossil fuels. While methane has a shorter atmospheric lifetime than CO2, it is estimated to be 28 times more effective at trapping heat over a 100-year timescale.

Overall, the greenhouse gases carbon dioxide and methane contribute to global warming by reducing the amount of thermal energy that is lost to space, leading to an increase in the Earth’s average temperature. The continued release of these gases into the atmosphere through human activities is a major environmental concern with far-reaching consequences

116
Q

State and explain strategies to reduce the effects
of climate change

A

planting trees, reduction
in livestock farming, decreasing use of
fossil fuels, increasing use of hydrogen and
renewable energy, e.g. wind, solar

117
Q

State and explain strategies to reduce the effects
of acid rain

A

use of catalytic converters in
vehicles, reducing emissions of sulfur dioxide
by using low-sulfur fuels and flue gas
desulfurisation with calcium oxide

118
Q

Explain how oxides of nitrogen form in car
engines and describe their removal by catalytic
converters, e.g. 2CO + 2NO → 2CO2 + N2

A

Oxides of nitrogen (NOx) are formed in car engines due to the high temperature combustion of fuel in the presence of oxygen. The two main oxides of nitrogen are nitrogen oxide (NO) and nitrogen dioxide (NO2).

Catalytic converters are devices fitted to cars that convert harmful exhaust gases into less harmful ones before they are released into the atmosphere. One way that catalytic converters can remove NOx is through a process called reduction. The reduction of NOx occurs in two stages:

First, carbon monoxide (CO) and unburned hydrocarbons in the exhaust gases react with oxygen over a catalyst to produce carbon dioxide (CO2) and water (H2O).

The second stage involves the use of a different catalyst that causes a reaction between the remaining NOx in the exhaust gases and the unreacted hydrocarbons. The NOx is reduced to nitrogen gas (N2) and water vapor (H2O) by the hydrocarbons.

The overall reaction can be written as:

2CO + 2NO → 2CO2 + N2

The catalyst used for this process is typically a mixture of platinum and rhodium. The catalytic converter can only function effectively when it is operating at a high temperature, which is why it is located close to the engine where the exhaust gases are still hot.

119
Q

Describe photosynthesis as the reaction itself

A

reaction between carbon dioxide and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light

120
Q

State the word equation for photosynthesis

A

carbon dioxide + water → glucose + oxygen

121
Q

State the symbol equation for photosynthesis

A

6CO2 + 6H2O → C6H12O6 + 6O2

122
Q

% of Nitrogen in the air

A

78%

123
Q

% of Oxygen in the air

A

21%

124
Q

% of Argon in the air

A

0.9%

125
Q

% of Carbon Dioxide in the air

A

0.04%

126
Q

Nitrogen Boiling Point

A

-196 C

127
Q

Argon Boiling Point

A

-186 C

128
Q

Oxygen Boiling Point

A

-183 C

129
Q

How are the gases in the air separated in industry?

A

Fractional Distillation of Liquid Air

130
Q

Fractional Distillation of the Air Process

A

1.. Compress the air to 150 times atmospheric pressure. This warms up the air, so it is then passes over cold water pipes)
2. Pressure is released, and air is allowed to expand rapidly. Causes temp to drop enough that the gases -> liquids. CO2 and H2O are removed easily as they are solid at this temperature.
3. Temp is slowly increased and the gases boil off one by one. Nitrogen - Argon - Oxygen

131
Q

O
I
L
R
I
G

A

Oxidisation is loss (of electrons)

Reduction is gain (of electrons)

132
Q

Bases

A

The oxide, hydroxide or carbonate of a metal that will react with an acid, forming a salt as one of the products.
Bases dissolved in water are alkalis.

133
Q

Amphoteric Metals

A

An oxide that displays both acidic and basic properties.

134
Q

Test for oxygen gases.

A

A glowing splint will relight in oxygen.

135
Q

Metal oxides are…

A

Basic

136
Q

Non-Metal oxides are…

A

Acidic

137
Q

3 elements of a water filter and their purposes.

A

> Carbon- Reduces chlorine in water
Ion-exchange resin- removes calcium, magnesium, lead, copper and aluminium.
Silve- Discourages the growth of bacteria in the filter.

138
Q

Desalination

A

The removal of salts from water to make it safe to drink.

139
Q

Positives of Fluoridation of Water.

A

> Reduces cavities.
Protects those with bad dental hygiene.
Protects from bacteria that causes heart disease.

140
Q

Negatives of Fluoridation of Water.

A

> Fluorosis- Weakens bones.
Benefit for teeth is not significant.
Ethically wrong- no consent from people.
Can cause learning difficulties and Alzheimers
Can’t control intake.

141
Q

Which metal rusts?

A

Iron

142
Q

What is needed for iron to rust?

A

Oxygen and Water.

143
Q

What prevents rusting?

A

> Paint
Oil/ Grease
Plastic
Less reactive metal
More reactive metal

144
Q

What prevents rusting?

A

> Paint
Oil/ Grease
Plastic
Less reactive metal
More reactive metal

145
Q

Galvanised

A

Iron or Steel objects that have been protected from rusting by a thin layer of zinc metal at their surface.

146
Q

Sacrificial Protection

A

An effective way to prevent rusting whereby a metal more reactive than iron (e.g zinc or magnesium) is attached to or coated on an object.

147
Q

Define chlorination

A

Adding chlorine to water in order to kill the bacteria in it

148
Q

Define aquifer

A

A rock that absorbs large amount of water

149
Q

Define reservoir

A

A place where water is treated and stored

150
Q

Define coagulant

A

Any binding agent to enable solid particles to stick together

151
Q

How is water cleaned using filtration and chlorination?

A
  1. The water is filtered to remove all the insoluble particles.
  2. Chlorine is added to sterilise it, remove any bacteria so that it’s safe to drink
152
Q

Chemical tests to identify the presence of water? (2)

A
  1. Anhydrous copper(II) sulphate. It goes from white to blue in the presence of water
  2. Cobalt(II) chloride paper. It goes from blue to pink in the presence of water
153
Q

Action of heat on:

  1. Hydroxides of Aluminium and the transition metals
  2. Nitrates of group I
  3. Nitrates of group II
  4. Nitrates of transition metals
A
  1. Reactant –> metal oxide + water
  2. Reactant –> metal nitrate + oxygen
  3. Reactant –> metal oxide + nitrogen dioxide + oxygen
  4. Same as 3
154
Q

Purpose of a catalytic converter?

The 3 different conversions that it does?

A

To convert toxic substances into less toxic substances

NO2/NO –> N2 + O2
CO –> CO2
Unburnt hydrocarbons –> CO2 + H2O

155
Q

Why does a catalytic converter have micro ducts?

A

To increase the surface area for the reactions to take place

156
Q

3 metals that make up the metal blocks in the catalytic converter

A
  1. Platinum
  2. Rhodium
  3. Palladium
157
Q

Limitations of a catalytic converter? (2)

A

1- Inefficient if it is not hot

2-Doesn’t start working for the first 6 miles when driving

Chemistry Flashcards (11 decks)

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