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Chemistry - norm > 5 - Chemistry in Industry > Flashcards

5 - Chemistry in Industry Flashcards

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1
Q

Where are most metals found?

A
  • Unreactive = in the ground
  • Reactive = in ores
  • The more reactive it is the harder it is to extract from a compound
  • Ores are finite resources
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2
Q

How do you separate metals from their oxides?

A
  • Reduction reaction

- Carbon is used as a reducing agent to separate copper oxide

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3
Q

Which metals can be extracted using carbon in a reduction reaction?

A

Only metals less reactive than carbon

  • Zinc, Iron, Tin
  • Heated with carbon monoxide
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4
Q

What happens with a more stable ore?

A

The metal is more reactive and difficult to get out of its compound

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5
Q

When do you use electrolysis to extract a metal?

A

When it is more reactive than carbon

- Potassium, sodium, calcium, magnesium, aluminium

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6
Q

What is aluminium’s ore?

A

Bauxite

- After mining and purifying a white powder is left leaving pure aluminium oxide (Al2O3)

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7
Q

How is aluminium extracted from its ore?

A

Electrolysis

  • Cryolite lowers the temperature from 2000C to 900C
  • This also makes it cheaper to run
  • Electrodes are made of graphite
  • The positive Al3+ ions attracted to the cathode where they pick up electrons and turn into aluminium ions (which sink to the bottom)
  • The negative O2- ions are attracted to the anode where they lose electrons and react with oxygen or carbon to form O2 or CO2
  • The anode gets worn down from the reacting oxygen so needs to be replaced
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8
Q

What are the half equations in the electrolysis of aluminium?

A

Anode: 2O2- –> O2 + 4e- (oxidation)
Cathode: Al3+ + 3e- –> Al (reduction)
A redox reaction

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9
Q

Why is electrolysis of aluminium expensive?

A
  • Uses lots of electricity
  • Needs lots of heat
  • The anode needs constant replacing
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10
Q

What are the raw materials needed in the extraction of iron?

A

Iron ore - iron
Coke (pure carbon) - reduction agent
Limestone - removes impurities in the form of slag

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11
Q

Describe the extraction of iron

A
  • Hot air is blasted into the furnace
  • Temperature = 1500*C
  • Coke burns to produce CO2 (C + O2 –> CO2)
  • The CO2 reacts with the unburnt coke to form CO2 (CO2 + C –> 2CO)
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12
Q

Describe the extraction of iron

A
  • Hot air is blasted into the furnace
  • Temperature = 1500*C
  • Coke burns to produce CO2 (C + O2 –> CO2)
  • The CO2 reacts with the unburnt coke to form CO2 (CO2 + C –> 2CO)
  • The carbon monoxide reduces the iron ore to iron (3CO + Fe2O3 –> 3CO2 + 2Fe
  • The iron is molten at this temperature and is very dense so runs to the bottom of the furnace and is tapped off
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13
Q

How are impurities removed in the extraction of iron?

A
  • The main impurity is sand (silicon dioxide) which has a very high melting point
  • The limestone is decomposed by the heat into calcium oxide and CO2 (CaCO3 –> CaO + CO2
  • The calcium dioxide reacts with the sand to form calcium silicate (slag) which is molten and tapped off (CaO + SiO2 –> CaSiO3)
  • The cooled slag is used for road building or in fertilisers
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14
Q

What are some properties of aluminium and iron?

A
  • Both dense and lustrous (shiny)
  • High melting points
  • Hard and strong
  • Malleable (can be hammered into a different shape)
  • Good conductors of heat and electricity
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15
Q

What are some uses of iron?

A
  • Wrought iron is pure iron and is malleable so is used for ornamental gates and railings
  • Cast iron (iron, carbon, silicon) is hard but brittle so used for manhole covers and cooking pans
  • Steel (iron and carbon) is very hard so used for car bodies and girders
  • Stainless steel (iron and chromium) is used for cutlery and cooking pans
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16
Q

What are some problems with iron?

A
  • It corrodes easily
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17
Q

What are some uses of aluminium?

A
  • Fizzy drink cans because it doesn’t corrode when in contact with water
  • In bicycle frames and aeroplanes because it is light and malleable
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18
Q

What are some uses for refinery gases?

A
  • Bottled gas
  • Heating
  • Pottery
  • Glass manufactures
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19
Q

What are some uses for refinery gases?

A
  • Bottled gas
  • Heating
  • Pottery
  • Glass manufactures
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20
Q

What are some uses for gasoline?

A

Fuel for cars

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21
Q

What are some uses for Naphtha?

A
  • Plastics
  • Paints
  • Dyes
  • Drugs
  • Explosives
22
Q

What are some uses for kerosene (paraffin)?

A
  • Jet engines
  • Domestic heating
  • Paint solvent
23
Q

What are some uses for diesel?

A

Fuel for diesel engines in cars, trucks, trains, boats, etc

24
Q

What are some uses for fuel oil?

A
  • Domestic central heating

- Fuel for big ships

25
Q

What are some uses for bitumen?

A
  • Road surfacing

- Asphalt for roofs

26
Q

What are the products of crude oil?

A
  • Bitumen
  • Fuel oil
  • Diesel
  • Kerosene (paraffin)
  • Naphtha
  • Gasoline
  • Refinery gases
27
Q

Fractional distillation of crude oil

A
  • A physical process (no chemical reactions)
  • Heated to the boiling point of the highest component
  • Separated into different hydrocarbon fractions
  • The longer the hydrocarbon the higher the boiling point
  • Bubble caps stop them from running back down
28
Q

How are pollutants produced?

A

By burning fuels (e.g. carbon monoxide, nitrogen oxides, sulphur dioxides, etc)

29
Q

How is carbon monoxide produced?

A
  • Formed when hydrocarbon fuels (e.g. petrol or diesel) are burnt without enough oxygen = incomplete combustion
  • Poisonous as it combines with haemoglobin in blood cells so not as much oxygen can be carried
  • Can lead to fainting, coma or death
30
Q

How is sulphur dioxide and nitrogen oxides produced?

A
  • When fossil fuels are burnt
  • Sulphur dioxide comes from sulphur impurities in fossil fuels
  • Nitrogen oxides are created when the temperature is high enough from nitrogen and oxygen in the air to react
31
Q

How is acid rain caused?

A
  • When sulphur dioxide mixes with clouds to form dilute sulphuric acid
  • Nitrogen oxide can also form nitric acid in clouds
  • Acid rain causes lakes to become acidic
  • Kills trees and damages limestone buildings
32
Q

Why is all rain slightly acidic?

A

Because carbon dioxide in the air reacts with water to produce a slightly acidic solution

33
Q

Why is all rain slightly acidic?

A

Because carbon dioxide in the air reacts with water to produce a slightly acidic solution

34
Q

How are hydrocarbons split?

A

By cracking which is a form of thermal decomposition as it breaks down molecules into simpler molecules through heat
- Produces alkenes which are used to make polymer

35
Q

Describe the conditions for cracking of hydrocarbons

A
  • Vaporised hydrocarbons are passed over a powdered catalyst
  • Catalyst = Silica (SiO2) and alumina (Al2O3)
  • Temperature = 600 - 700*C
36
Q

Describe the cracking of paraffin in the lab

A
  • Heat the paraffin and silica and alumina alternatively until the paraffin vaporises and the catalysts glow red
  • The heated paraffin cracked when passed over the heated catalyst
  • Small alkanes collect at the end of the boiling tube while alkene gases travel down the delivery tube
  • The alkenes are collected through water using a gas jar
  • Always makes an alkane and alkene
37
Q

Why is the Haber process used?

A

To make ammonia from nitrogen and hydrogen

38
Q

What are the conditions in the Haber process?

A

Nitrogen = air
Hydrogen = natural gas or from cracking hydrocarbons
Pressure = 200 atmospheres
Temperature = 450*C
Catalyst = Iron
- it is a reversible reaction (forward = exothermic)

39
Q

Describe the reversible reaction in the Haber process

A
  • High pressure favours the forward reaction so pressure as high as possible
  • The forward reaction is exothermic so needs a lower temperature
  • Low temperature = slow reaction
  • 450*C is a compromise between high yield and high speed
  • The unused hydrogen and nitrogen are recycled so nothing is wasted
40
Q

What are some uses for ammonia?

A
  • In the Ostwald process to make nitric acid
  • You can react ammonia with nitric acid to get ammonium nitrate
  • Good for fertilisers because it has nitrogen from two sources so more concentrated and is more effective than organic fertilisers
41
Q

Why is the Contact Process used?

A

To make sulphuric acid

42
Q

Describe the Contact Process

A
  • Sulphur is burnt in air or sulphide ores are roasted to make sulphur dioxide (s + O2 –> SO2
  • The sulphur dioxide is oxides to form sulphur trioxide (2So2 + O2 2SO2)
  • The sulphur trioxide is dissolved in concentrated sulphuric acid to form liquid oleum (SO3 + H2SO4 –> H2S2O7)
  • The oleum is diluted with water to form concentrated sulphuric acid (H2S2O7 + H2O –> 2H2SO4)
43
Q

What are the conditions for the Contact Process?

A 
Temperature = 450*C
Pressure = 2 atmospheres
Catalyst = Vanadium(V) oxide (V2O5)
44
Q

What are some uses for sulphuric acid?

A
  • Fertilisers = mostly in phosphate fertilisers
  • Detergents
  • Paints = used to make titanium dioxide which is a white pigment in paints
45
Q

Describe the electrolysis of brine

A
  • Carbon electrodes
  • Hydrogen gas is given off at the cathode (two hydrogen ions accept two electrons to become one hydrogen molecule)
  • Chlorine gas is given off at the anode (two chloride ions lose their electrons to become one chlorine molecule)
  • The sodium ions and hydroxide ions from the water stay in the solution leaving sodium hydroxide
46
Q

What are the half equations for the electrolysis of brine?

A

Cathode = 2H+ + 2e- –> H2

Anode 2Cl- –> Cl2 + 2e-

47
Q

What are the half equations for the electrolysis of brine?

A

Cathode = 2H+ + 2e- –> H2

Anode 2Cl- –> Cl2 + 2e-

48
Q

What are some uses of chlorine?

A
  • Used to sterilise water supplies
  • To make bleach
  • To make HCl
49
Q

What are some uses of hydrogen?

A
  • In the Haber process
  • To change oils into fats
  • For making margarine
50
Q

What are some uses of sodium hydroxide?

A
  • It is a strong base
  • Used to make soaps
  • Used to make bleach
  • Used to make paper pulp
51
Q

What are the products from the electrolysis of brine?

A
  • Chlorine gas
  • Hydrogen gas
  • Sodium hydroxide solution

Chemistry - norm (6 decks)

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