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GCSE chemistry > C6.1 Improving processes and products > Flashcards

C6.1 Improving processes and products Flashcards

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1
Q

What elements do plants need?

A

Nitrogen , Phosphorus , Potassium

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2
Q

If a plant receives a limited supply of these elements…

A

Plants will not grow well and show symptoms of mineral deficiency

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3
Q

Lack of nitrogen causes?

A

Poor growth , yellow leaves

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4
Q

Lack of phosphorus causes?

A

Poor root growth , discoloured leaves

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5
Q

Lack of Potassium causes?

A

Poor fruit growth , discoloured leaves

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6
Q

Fertilisers

A

Substance that replenish and replace elements used by plants as they grow

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7
Q

In what form can plant roots absorb these elements

A

When they are in a water soluble form :
- nitrate ions ( NO3-)
-phosphate ions ( PO34-)
-potassium ions ( K+)
-ammonium ions ( NH4+)

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8
Q

NPK fertilisers

A

Provide nitrogen phosphorus and potassium in water soluble compounds

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9
Q

What is the Haber Process ?

A

Manufactures Ammonia from nitrogen and hydrogen
-reversible reaction

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10
Q

Word Equation for the Haber Process:

A

N2 ( g ) + 3H2 ( g ) <——> 2NH3 ( g )

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11
Q

Which raw materials are required for the Haber Process?

A

-air
-natural gas
-steam

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12
Q

What percent of ammonia is used to make fertilisers?

A

80%

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13
Q

The atmosphere consists of ___% nitrogen

A

78%

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14
Q

How is nitrogen manufactured for the Haber Process?

A

Fractional distillation of liquified air

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15
Q

How is hydrogen manufactured for the Haber Process?

A

Reacting natural gas ( methane ) with steam

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16
Q

What are the conditions required for the Haber Process?

A

-presence of iron catalyst
-high temperature
-high pressure

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17
Q

Ammonium nitrate

A

NH4NO3

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18
Q

Ammonium sulfate

A

(NH4)2SO4

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19
Q

Ammonium Phosphate

A

(NH4)3PO4

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20
Q

Potassium Nitrate

A

KNO3

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21
Q

Which compounds of fertilisers can we make in the lab ?

A

-potassium sulfate
-ammonium sulfate

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22
Q

Describe the method of making potassium sulfate in the lab (6)

A

Made from potassium hydroxide ( KOH) and sulphuric acid ( H2S04 )
-add KOH to a conical flask alongside a few drops of phenolphthalein indicator
-add dilute sulphuric acid from a burette , stopping when the indicator changes from pink to colourless
-add ‘activated charcoal’ , this binds/attracts to the phenolphthalein which can then be easily filtered out of the mixture to avoid including any impurities
-warm the filtrate to gently evaporate the water , leaving potassium sulfate behind

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23
Q

Why is single indicator ( phenolphthalein or methyl orange ) used instead of universal indicator ?

A

This provides a distinct colour changes , so adding this enables you to determine the exact point when the alkali has been neutralised

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24
Q

How can the experiment be made more accurate ?

A
  • use a white tile which makes the colour change more distinct and easier to see
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25
Q

How is ammonium sulfate made in the lab?

A

-place dilute ammonia solution in a conical flask with methyl orange indicator
-add dilute sulphuric acid from a burette / dropping pipette , stopping when the indicator changes from yellow to red
-when reaching the end point ( distinct colour change ) , add a little extra ammonia solution to ensure the reaction is complete

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26
Q

What are some hazards when making ammonium sulfate and how can these be prevented ?

A

-ammonia and potassium hydroxide are highly alkaline and irritant : wear gloves , eye protection and lab coat
-ammonia gives off an irritating sharp smell : carry out the experiment in a fume cupboard or be cautious when inhaling near the experiment

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27
Q

Batch process

A

Small amount at one time eg in a school lab

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28
Q

Continuous process

A

Large amounts and continue all the time eg large industrial processes

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29
Q

Features of batch process are?

A

-low rate of production
-low cost
-large no of people / workers needed
-frequent shut down periods
-low ease of automating the process

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30
Q

Features of continuous processes are?

A

-high rate of production - ADV
-high cost of equipment - DISADV
-small no of workers needed - ADV
-rare shut down periods - ADV
-high ease of automating

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31
Q

What is the difference between making substances in a lab vs industrially in a factory ?

A

Lab starts off with pure substances bought from chemical manufacturers , whereas fertiliser factors start with raw materials ( which must be purified either before or the whole substance after )

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32
Q

What type of reaction is the Haber Process?

A

Exothermic

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33
Q

Conditions for the Haber Process ?

A

-pressure of 200 ATM ( 20MPa )
-a temperature of 450 degrees Celsius
-an iron catalyst

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34
Q

Under these usual conditions , what is the equilibrium yield of ammonia ?

A

30%

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35
Q

Despite the low equilibrium yield , why is ammonia still made ( The Haber Process ) conducted under such conditions?

A
  • if pressure is increased , equilibrium position moves to the right and equilibrium yield of ammonia increase
    -however this is extremely hazardous and also expensive
    -the higher equilibrium yield does not justify the additional costs , so manufacturers must comprise with a lower pressure
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36
Q

What factors determine the temperature chosen for the Haber Process?

A

-if temp is increased, equilibrium position moves to the left , decreasing yield of ammonia therefore a high equilibrium yield is favoured by a low temperature
-therefore manufacturers have to compromise with temp and pick a temperature ( 450 C ) low enough to produce a reasonable yield but high enough to achieve a good rate of reaction
-additionally , the iron catalyst works more efficiently about 400 C

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37
Q

What other conditions are chosen to increase yield of ammonia during the Haber Process?

A

-mixture of gases leaving the reaction vessel is cooled so that ammonia is liquefied
-this allows ammonia to be removed and products ( unreacted nitrogen and hydrogen ) to be recycled
-this improves the overall yield to 95%

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38
Q

Uses of sulfuric acid?

A

Fertilisers , oil refining , metal extraction , making paints and polymers

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39
Q

How many steps are needed to synthesise sulfuric acid?

A

3 steps , including the Contact process

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40
Q

Which raw materials are required to make sulfuric acid?

A

-sulfur
-air ( any source of oxygen )
-water

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41
Q

Stage 1

A

sulfur burns in air to produce sulfur dioxide
-exothermic reaction

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42
Q

Word equation for stage 1 of synthesising sulfuric acid?

A

S + O2 ——> SO2

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43
Q

Stage 2 of producing sulfuric acid?

A

The Contact Process:
-sulfur dioxide and oxygen react together to produce sulfur trioxide
-exothermic reaction

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44
Q

Word equation for the Contact Process ( Stage 2 ) ?

A

2SO + O2 <——> 2SO3

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45
Q

What are the conditions chosen for the (reversible) Contact process?

A

-pressure of 2ATM
-temperature of 450 degrees Celsius
-a vanadium oxide catalyst , V2O5
Produces an equilibrium yield of 96%

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46
Q

Stage 3 of producing sulfuric acid?

A

Sulfur trioxide is converted tosulfuric acid

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47
Q

Word equation for stage 3?

A

H20 + SO3 ——> H2SO4

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48
Q

Renewable raw materials can be…

A

Replaced as they are used , and technically should not run out

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49
Q

How is ethanol made?

A

Via the process of fermentation , relies on yeast

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50
Q

What is the role of yeast during fermentation?

A

-it contains enzymes which catalyse the conversion of glucose solution to carbon dioxide and ethanol

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51
Q

Word equation for fermentation ?

A

Glucose ——> Carbon Dioxide + Ethanol

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52
Q

Chemical equation for fermentation including state symbols?

A

C6H12O6 (aq) ——> 2CO2 (g) + 2C2H5OH (aq)

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53
Q

How can fermentation be carried out in a school laboratory?

A

-place glucose solution and yeast in a conical flask
-use a rubber bung to seal the conical flask , collecting the gas and bubbling it through limewater

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54
Q

Non renewable materials are…

A

Materials that are used faster than they can be replaced

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55
Q

How is ethanol produced from non renewable materials

A

Ethene is obtained from crude oil , and is then hydrated to form ethanol

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56
Q

What type of reaction is the hydration of ethene ?

A

Exothermic and reversible

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57
Q

Chemical equation for the hydration of ethene?

A

C2H4 (g) + H2O (g) <——> C2H5OH ( g )

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58
Q

What is the state of steam?

A

Gas
- H2O with the state symbol (g)

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59
Q

Why can’t the hydration of ethene be carried out in a school laboratory?

A

-requires temp of 300 degrees Celsius
-pressure of 60ATM
-presence of a phosphoric acid catalyst

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60
Q

What are the ways in which ethanol is produced?

A

Fermentation of sugars and Hydration of ethene

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61
Q

Positive features of fermentation of sugars?

A

-low costs of raw materials
-can be carried out in school lab ; as it is carried out in moderate conditions
-low energy requirements

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62
Q

Negative features of fermentation of sugars?

A

-low rate of reaction
-low percentage yield
-low purity of product ( requires fractional distillation and filtering )

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63
Q

Positives of hydration of ethene?

A

-high rate of reaction
-high percentage yield
-high purity of product ( no by products )

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64
Q

Negatives of hydration of ethene?

A

-high cost of raw materials
-high temp and pressure
-high energy requirements

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65
Q

What is an ore?

A

A rock or mineral which contains enough metal to make it economical to extract it - the value of the metal is more than the cost of extracting it

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66
Q

What metal compound is found in malachite?

A

Copper carbonate

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67
Q

What metal compound is found in bauxite?

A

Aluminium oxide

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68
Q

What metal compound is found in haematite?

A

Iron ( III ) oxide

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69
Q

Where does carbon lie in the reaction series?

A

In between aluminium and zinc

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70
Q

What possible methods could be used to extract metal from its ores?

A

-electrolysis
-if the metal is less reactive than carbon , cheaper methods are used instead by heating the metal with carbon or carbon monoxide

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71
Q

Why is electrolysis not used to extract metal from its ores?

A

Electricity is expensive

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72
Q

Describe the first stage of extracting copper from copper (II) sulfide : word equation , chemical equation

A

Stage 1 : the copper (II) sulfide is “roasted” in air
Copper (II) sulfide + oxygen ——> copper (II) oxide + sulfur dioxide
2CuS(s) + 3O2(g) ——> 2Cu(s) + CO2(g)

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73
Q

Describe the second stage of extracting copper from copper (II) sulfide: word equation , chemical equation

A

Stage 2:Copper oxide is heated with carbon
Copper(II) oxide + carbon ——> copper + carbon dioxide
2CuO(s) + C(s) ——> 2Cu(s) + CO2(g)

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74
Q

Is the extraction of copper a redox reaction?

A

Yes

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75
Q

In the extraction of copper what is reduced?

A

Copper(II) oxide is reduced and is the oxidising agent

76
Q

In the extraction of copper , what becomes oxidised?

A

Carbon gains oxygen and acts as the reducing agent

77
Q

How else can copper oxide be reduced to copper?

A

-heating it with methane or with hydrogen

78
Q

Why is copper extracted by heating copper oxide with carbon?

A

It is less reactive and is therefore displaced
It is a much cheaper process than electrolysis

79
Q

How is iron extracted from its ore ?

A

Using a large reaction container called a blast furnace

80
Q

What ore is iron extracted from?

A

Haematite

81
Q

Which raw materials are used for the extraction of iron ( added to the top of the blast furnace)

A

-iron ore ( eg haematite which contains iron (II) oxide
-coke
-limestone

(Hot air is forced in at the bottom of the blast furnace)

82
Q

Why is limestone added to the blast furnace?

A

It is used to purify the iron

83
Q

Describe what occurs in the blast furnace (6)

A

Carbon reduces iron (III) oxide to iron , but carbon monoxide is the main reducing agent. So it is formed when coke reacts with carbon dioxide . The CO then reduces the iron oxide to iron . Molten iron trickles downwards in the blast furnace , but also contains sandy impurities from the iron ore . These impurities are removed using limestone , forming molten calcium silicate ( slag ) . This floats on top of the molten iron , and both the iron and slag are removed separately at the bottom of the furnace.

84
Q

Describe the steps taken ( and chemical equation ) to reduce iron (iii) oxide to iron:

A

Stage 1 : Coke burns in hot air , producing CO2
C + O2 —> CO2
Stage 2 : More coke reduces the carbon dioxide , forming carbon monoxide
C + O2 —> 2CO
Stage 3 : Carbon monoxide reduces iron oxide to iron at around 1500:
3CO + Fe2O3 —> 3CO2 + 2Fe

85
Q

What is slag?

A

Molten calcium silicate

86
Q

After iron (III) oxide is reduced to iron , what happens?

A

At temps of 1500 degrees Celsius , the iron becomes molten and trickles downwards in the blast furnace , which contains sandy impurities from the iron ore . This is removed using limestone , which is mostly calcium carbonate

87
Q

How are impurities removed from the molten iron?

A

Stage 1 : Calcium carbonate decomposes in high temperatures
CaCO3 ( s) —> CaO (s) + CO2 ( g)
Stage 2 : Calcium oxide reacts with silica from sandy impurities forming calcium silicate
CaO (s) + SiO2 (g) —> CaSiO3 (l)

88
Q

After the iron is purified , what happens?

A

The slag floats on top of the molten iron , and they are both separately removed at the bottom of the blast furnace in the liquid state

89
Q

Which ore is aluminium found in?

A

Bauxite

90
Q

Why can’t aluminium be extracted from its ore in the same way as iron or copper?

A

It is more reactive than carbon , and must be extracted via electrolysis as opposed to heating compounds

91
Q

Why is it a problem to electrolyse aluminium oxide?

A

It does not dissolve in water and has a very high melting point ( over 2000 degrees Celsius ) which would be costly to maintain

92
Q

Electrolysis only works if the compound is in solution or molten - why?

A

So the ions are free to move throughout the fluid and towards their respective electrode

93
Q

How is aluminium oxide electrolysed ?

A

-it is dissolved in molten cryolite ( which has a much lower BP )
-the mixture is contained in a huge electrolysis cell made with steel and lined with graphite
-the graphite lining acts as the cathode
-a series of large graphite blocks acts as the anode

94
Q

Why is cryolite used in the electrolysis of aluminium oxide?

A

It is mixed with the aluminium oxide as it has a much lower boiling point and therefore can be molten at temperatures of around 900 as opposed to 1500
This reduces energy costs , which is the most important factor determining the cost of aluminium extraction

95
Q

The cathode during electrolysis of aluminium oxide is:

A

The graphite lining of the electrolysis cell

96
Q

The anode during electrolysis of aluminium oxide is:

A

A series of large graphite boocks

97
Q

What happens at the cathode during electrolysis of aluminium oxide?

A

Aluminium is produced
Al3+ + 3e- —> Al

98
Q

What happens at the anode of the electrolysis of aluminium oxide?

A

Oxygen is produced at the anode(s)
2O2- —> O2 + 4e-

99
Q

Why might the anodes in an aluminium electrolysis cell need to be sometimes replaced?

A

They will react and lose mass , eventually decreasing in size
-graphite is a form of carbon so will form carbon dioxide

100
Q

What is acid mine drainage?

A

Mines often flood , causing metal sulfides to be oxidised underwater . This produces sulfuric acid , and also other metal ores . This forms soluble metal compounds which leave with the water as it drains from the mine

101
Q

What do bacteria do in bioleaching?

A

They oxides iron (II) and sulfide ions and use the energy transferred , sulfuric acid is also produced in the presence of water and oxygen . This breaks down copper sulfide ores and other minerals , releasing copper (II) ions and other metal ions

102
Q

Low grades ores

A

Ores that contain too little metal for traditional methods to be profitable

103
Q

Advantages of bioleaching?

A

It’s cheaper than traditional mining and processing
Utilises low grade ores
Natural process which does not need any special treatment

104
Q

Disadvantages of bioleaching :

A

Slow process
May sometimes produce toxic substances
Care must be take to avoid these , and sulfuric acid, escaping into water and soil

105
Q

What is phytoextraction?

A

When a crop is planted in a soil containing low grade ore or mine waste . A “complexing agent” is added so plants can absorb mineral ions more easily . The plants are then harvested and burnt to produced an ash with a high concentration of the metal . The metal can then be extracted , as if the ash was a high grade ore.

106
Q

Advantages of phytoextraction:

A

Cheaper than traditional mining and processing
Produces less waste and involves smaller energy transferred
Closer to being a carbon neutral activity as it releases CO2 ( when plants are burnt ) but also absorbs it ( during photosynthesis of the plants growth )

107
Q

Disadvantages of phytoextraction:

A

-slow process , crops may need replanting and harvesting for several years
-dependent on weather for photosynthesis

108
Q

Compare the processes of phytoextraction and bioleaching

A

-phytoextraction uses certain plants to extract metals from low grade ores whereas bioleaching makes use of bacteria to break down copper sulfide
-both are relatively cheap
-phytoextraction adds to pollution as co2 is produced , whereas bioleaching does not have any effects ( unless toxic substances are produced)
-both processes are slow

109
Q

What is an alloy?

A

A mixture of two or more elements , at least one of which is metal

110
Q

Alloy of steel contains which metal?

A

Iron

111
Q

Properties of steel

A

High tensile strength and ductile

112
Q

Uses of steel

A

Buildings , bridges , cars

113
Q

Duralumin allot contains which metals?

A

Aluminium and copper

114
Q

Properties of duralumin

A

Strong and lightweight

115
Q

Uses of duralumin

A

Aircraft parts

116
Q

Solder contains which metals?

A

Tin and copper

117
Q

Uses of solder?

A

Joining electrical components and copper pipes

118
Q

Brass is made of which metals?

A

Copper and zinc

119
Q

Uses of brass

A

Musical instruments and coins

120
Q

Bronze is made up of which metals?

A

Copper and tin

121
Q

What is bronze used for?

A

Bells , propellers for ships , musical instruments , metal artworks

122
Q

Solders melting point ?

A

227 degrees Celsius

123
Q

Why is the melting point of solder ( 227 ) useful for electrical components?

A

-it can join them without damaging them
-as it can easily become molten and flow into gaps between components , and then solidify quickly
-metals are good conductors of electricity , so the soldered joint allows an electric current to pass

124
Q

When metals are bent or stretched , what happens to their atoms?

A

The layers of metal ions slide over one another

125
Q

Why are alloys often stronger and harder than their individual metals? Example?

A

-the difference metal atoms are difference sizes , making it hard for the same metal ions to slide over one another
An example of this would be copper

126
Q

Features of brass?

A

-conducts electricity ( not as well as copper )
-stronger then copper
-resists corrosion

127
Q

Brass resists corrosion , meaning ?

A

It does not react easily with wir or water

128
Q

Features of bronze?

A

-harder and stronger than copper
-resists corrosion

129
Q

Corrosion

A

The reaction of a metal with substances in its surroundings , such as air and water

130
Q

Why does silver corrode? What is formed?

A

( does not react easily with oxygen or water )
-corrodes in the presence of hydrogen sulfide , a gas naturally produced by bacteria
-this reacts with silver in the presence of oxygen or water
-this produces a think layer of black silver sulphide

131
Q

How is the corrosion of silver avoided?

A

By constantly cleaning objects made of sikver

132
Q

Hydrogen sulfide formula

A

H2S

133
Q

Silver sulphide formula

A

Ag2S

134
Q

Which type of metals do nor corrode?

A

Highly unreactive metals, such as gold and platinum

135
Q

What type of reaction is rusting?

A

A redox reaction , iron is oxidised and oxygen is reduced

136
Q

Word equation for when iron rusts

A

Iron + oxygen + water ——> hydrated iron (III) oxide

137
Q

What must be present for rusting to occur?

A

Water and oxygen

138
Q

What else speeds up rate of rusting?

A

Salt water , dissolved salts

139
Q

How is rusting prevented?

A

-painting
-coating with oil , grease , or plastic
-plating with zinc ( galvanising )
-plating with tin

140
Q

What is the downside to using methods such as painting and coating to prevent rusting?

A

If the paint , oil , or grease is damage , rusting will start on the exposed metal and continue underneath the paint , causing it to flake off . Eventually more and more fresh metal will be exposed to air and water

141
Q

Name better ways of preventing rusting:

A

-sacrificial protection
-galvanising

142
Q

When is sacrification used?

A

When a low reactivity metal is coated with a higher reactivity metal

143
Q

Describe how sacrificial protection works

A

-metal is coated with another metal more reactive than it, such as magnesium or zinc
-as long as the metal remains in contact with the coated metal, the more reactive metal corrodes frost - hence sacrificing itself to protect the iron/steel
-

144
Q

Why is sacrificial protection useful?

A

It is convenient for when painting or coating is difficult

145
Q

Example of sacrificial protection?

A

Ships have zinc or magnesium bolts boosted into their hulls below the waterline , protecting it from rusting
-they have to be replaced as they gradually corrode

146
Q

Explain why a more reactive metal will corrode first and quicker than a less reactive metal

A

Sacrificial metals such as magnesium and zinc lose electrons more easily than iron does ( more reactive = more easily loses electrons ) , and are also more readily oxidised than iron

147
Q

What happens to iron during rusting?

A

The atoms lose electrons and are oxidised to iron (III) ions
Fe ——> Fe3+ + 3e-

148
Q

How does metal plating work?

A

A layer of metal is plated onto an iron or steel metal object , preventing air and water reaching the metal below

149
Q

What is the difference between metal playing and galvanising

A

Galvanising is specific to plating with molten zinc

150
Q

Galvanising

A

Dipping the metal object into molten zinc , allowing it to cool and solidify

151
Q

What does galvanising do?

A
  1. Stops air and water reaching iron or steel below
  2. Acts as a sacrificial metal so object is protected , even if zinc layer is damaged
152
Q

Another example of metal plating:

A

Tin plating

153
Q

What is tin plating?

A

Electroplating the steel object with tin , or dipping it in molten tin

154
Q

Example of tin plating?

A

Insides of steel food cans are protected by tin plating
Farm gates

155
Q

Disadvantages of Tin plating:

A

Tin is less reactive than iron , so if it becomes damaged , the steel would act as a sacrificial metal and rust even faster than normal

156
Q

What are ceramics ?

A

Hard , non metallic metals

157
Q

Examples of ceramics

A

Brick , China , Porcelain , Glass

158
Q

Describe the structure of ceramics

A

-contain metals and non metals
-forming giant ionic lattices or giant covalent structures

159
Q

Typical properties of ceramics?

A

-high MP
-hard and stiff , but brittle
-poor conductors of electricity and heat

160
Q

Why are ceramics so unreactive?

A

The compounds in them are mainly oxides

161
Q

How is glass made?

A

Melting sand , and then allowing it to cool and solidify
-has an irregular giant structure without crystals , and is therefore usually transparent

162
Q

How are other ceramics produced?

A

-heating clay to high temps
-forming tiny crystals , joined together by glass

163
Q

How do China and porcelain appear glassy ?

A

Coated in a glaze and reheated , forming a smooth , hard and waterproof surface

164
Q

What are the ideal properties for a material used for an overhead electrical cable?

A

-good conductor of electricity
-lightweight
-strong ( does not snap easily )
-resist corrosion

165
Q

Which metals are suitable for overhead electrical cables?

A

-aluminium ( good conductor , good tensile strength , lightweight )
-copper ( best conductor , low tensile strength , very high density )
-steel ( low conductor , best tensile strength , heavy )

166
Q

Which materials are good for insulators?

A

-glass
-porcelain - best for insulators
-poly (propene)

167
Q

What is poly(propene)?

A

A tough , flexible polymer

168
Q

What is a composite material?

A

Material made from two or more materials with different properties are combined

169
Q

How are composite materials used in clothes?

A

Polyester cotton = cotton thread and polyester fibre
-more hardwearing and easier to wash and dry

170
Q

Describe another composite material :

A

Fibre ( carbon ) glass = glass ( carbon ) fibres in a resin
Strong , tough , lightweight

171
Q

Uses of fibreglass :

A

Canoes , boats , surfboard
Carbon fibre : sports equipment and racing cars

172
Q

What materials is concrete made from?

A

Aggregate , sand , and cement ( and water )

173
Q

Properties of concrete

A

High compressive strength - good for foundations
Low tensile strength - cracks and breaks under high pressure

174
Q

How is the low tensile nature of concrete resolved?

A

By embedding steel rods in concrete ( which have a high tensile strength )
-creates the composite material called steel-reinforced concrete

175
Q

Plywood

A

A composite material in which thin sheets of wood are glued together in layers so the grains are at right angles to each other
-resists bending
-used for floors and walls

176
Q

What is a life cycle assessment ?

A

A cradle-to-grave analysis of the impact of making , using , and disposing of a manufactured product

177
Q

What data should a LCA include?

A

-sustainability
-environmental impact
-life span of the product and whether it can be recycled
-disposal / how easily the materials decompose

178
Q

What happens to materials and products if they are unable to be recycled?

A

They will end up in landfill sites as waste , which is not an efficient use of resources

179
Q

Reasons for the importance of recycling are…

A

-conserving limited raw materials and energy resources
-reducing release of harmful substances into the environment
-reducing waste

180
Q

Factors affecting whether or not a product should be recycled are…(4)

A

-how easily waste can be collected and sorted
-amount and type of any by products released by recycling
-cost of recycling compared to disposal in landfill or incineration
-amount of energy involved at each stage

181
Q

Why is it important for materials to be sorted before they are recycled?

A

So that materials are not contaminated and can be used for their purposes

182
Q

How are metals recycled?

A

Melted by heating until molten , and poured into moulds to produce blocks called ingots

183
Q

How is paper recycled?

A

Mixed with water , cleaned , rolled and heated to make new paper

184
Q

How is glass recycled?

A

Melted by heating , and moulded into new glass objects

185
Q

How are polymers like PET and poly(propene) recycled?

A

Melted and formed into new objects

GCSE chemistry (3 decks)

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