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CHEMISTRY based on CGP > Section 5: Chemistry in Industry > Flashcards

Section 5: Chemistry in Industry Flashcards

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1
Q

if a metal is reactive, is it harder or easier to extract from a compound than a less reactive one?

A

harder

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2
Q

what reducing agent is used to separate a metal (that is fairly unreactive) from the oxygen in its oxide? how does it achieve this?

A

carbon, by displacement, e.g. 2CuO + C –> 2Cu + O2

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3
Q

which 5 metals from the reactivity series are extracted using electrolysis?

A

Potassium, sodium, lithium, calcium, magnesium

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4
Q

carbon can only be used to extract metals from oxygen (by extraction) when the metal is more/less reactive than the carbon itself?

A

less

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5
Q

what kind of metals is electrolysis used to extract? (hint: reactivity)

A

metals that are more reactive than carbon

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6
Q

aluminium is more reactive than carbon. What metho is used to extract it from its ore?

A

electrolysis

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7
Q

what is the main Aluminium ore?

A

bauxite

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8
Q

after mining and purifying bauxite, what is the identity of the white powder you are left with?

A

pure aluminium oxide, Al2O3

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9
Q

What is the symbol for aluminium oxide?

A

Al2O3

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10
Q

what is the substance used as the electrolyte in the extraction process for aluminium? how?

A

cryolite- aluminium oxide is dissolved in it

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11
Q

how does cryolite help to lower the cost of aluminium extraction?

A

reduces the temp. needed to carry out electrolysis, as it has a lower melting point than aluminium oxide, which makes the process cheaper to run

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12
Q

what is cryolite?

A

a less common ore of aluminium oxide

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13
Q

why must the cryolite be molten?

A

free electrons are needed for electrolysis to occur

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14
Q

what are the electrodes used in the extraction of aluminium oxide and why?

A

graphite- a good conductor of electricity

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15
Q

what is the reaction (half equation) that occurs at the NEGATIVE electrode, the cathode, during the extraction of aluminium by electrolysis? what kind of reaction is this?

A

Al3+ + 3e- –> Al

reduction

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16
Q

what is the reaction (half equation) that occurs at the POSITIVE electrode, the anode, during the extraction of aluminium by electrolysis? what kind of reaction is this?

A

2O2- –> O2 + 4e-

oxidation

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17
Q

what is a observation you could make when looking at the anode during the electrolysis of aluminium oxide and why?

A

fizzing; CO2 and O2 gas from the negative O2- ions attracted to the anode and having lost electrons

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18
Q

why is electrolysis expensive? (3)

A
  1. Uses a lot of electricity
  2. Sometimes uses a lot of heat energy- the electrolyte must by molten/a liquid
  3. The positive electrodes need replacing; they disppear
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19
Q

what is the scientific name and symbol equation for iron ore?

A

hematite, Fe2O3

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20
Q

how is iron extracted from its ore? give 2 details

A

by reduction in a blast furnace

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21
Q

what is coke made up of and why is it used in iron extraction?

A

carbon, for reducing the iron oxide to iron metal

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22
Q

what is the role of limestone in iron extraction?

A

takes away impurities in the form of slag

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23
Q

what is the symbol equation representing the burning of coke to form carbon dioxide?

A

C + O2 –> CO2

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24
Q

what is the symbol equation representing the reaction of CO2 with unburnt coke?

A

CO2 + C –> 2CO

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25
Q

what is the symbol equation showing the reduction of iron ore to iron?

A

3CO + Fe2O3 –> 3CO2 + 2Fe

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26
Q

what is the word equation showing the reduction of iron ore to iron?

A

carbon monoxide + iron oxide –> carbon dioxide + iron

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27
Q

what is the main impurity in the extraction of iron in a blast furnace?

A

sand - silicon dioxide

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28
Q

what is the symbol equation to show the decomposition of limestone by the heat in a blast furnace?

A

CaCO3 –> CaO + CO2

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29
Q

what does the calcium oxide formed by the decomposition of limestone in a blast furnace react with sand to form? What is the symbol equation to show this?

A

calcium silicate, or slag

CaO + SiO2 –> CaSiO3

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30
Q

what are 2 uses of cooled slag?

A

fertiliser, road-building

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31
Q

what is the temperature in a blast furnace?

A

1500 degrees

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32
Q

what 2 things is aluminium useful for making and which of its properties do they depend on?

A
  1. Drink cans/products that come into contact with water; aluminium doesn’t corrode
  2. Bicycle frames/ aeroplanes/ products where the weight is important; aluminium is less dense than iron
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33
Q

what is the main problem with using iron?

A

it rusts

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34
Q

why do some of the products containing iron combine it with other metals to form alloys?

A

to prevent it from rusting, make it harder

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35
Q

what are two alloys of iron and what are their uses?

A
  1. Steel: car bodies and gliders

2. Cast iron: manhole covers, cooking pans

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36
Q

why is hot air blown into the blast furnace during iron extraction?

A

to make the coke burn faster than usual and raise the temp. to 1500

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37
Q

during the fractional distillation of crude oil, what are the bubble caps in the fractionating column for?

A

to stop the separated liquids fromrunning back down the fractionating column and remixing

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38
Q

do longer hydrcarbons have higher or lower boiling points than shorter chains?

A

higher

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39
Q

what is the temperature gradient from the bottom to the top during the fractional distillation of crude oil?

A

hot at the bottom, gradually cooler as you go up

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40
Q

What are the seven fractions in the fractional distillation of crude oil, in order of increasing length of hydrocarbon chain?

A 
Refinery Gases
Gasoline
Naptha
Kerosene (paraffin)
Diesel
fuel oil
bitumen
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41
Q

is fractional distllation a chemical or physical process? why(not)?

A

physical; no chemical reactions

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42
Q

what are refinery gases used for?

A

bottled gas, heating, pottery & glass manufacture (clean-burning fuel)

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43
Q

what is gasoline used for?

A

fuel for cars etc

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44
Q

what is naptha used for?

A

used to make plastics, dyes, drugs, explosives, paints, and as a feedstock in the chemical industry

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45
Q

what is kerosene (paraffin) used for?

A

Jet engines, domestic heating, paint solvent

46
Q

what is diesel used for?

A

fuel for diesel engines in cars, trucks, trains, boats

47
Q

what is fuel oil used for?

A

fuel for big ships, domestic central heating

48
Q

what is bitumen used for?

A

road surfacing, asphalt roofs

49
Q

when is carbon monoxide released into the atmosphere?

A

when hydrocarbon fuels are burnt without enough oxygen - incomplete combustion

50
Q

how is carbon monoxide harmful to humans?

A

combines with haemoglobin to prevent it reacting with oxygen to form oxyhaemoglobin meaning the blood can carry less oxygen around the body. This can lead to fainting, a coma or death

51
Q

when are sulphur dioxide and nitrogen oxide pollutants released into the atmosphere?

A

when fossil fuels are burnt

52
Q

what are the conditions needed for nitrogen oxides to be created? example for when this occurs?

A

very high temp, high enough for oxygen and nitrogen in the air to react - often in car engines

53
Q

all rain is slightly acidic. Why is this and what are the symbol and word equations to represent it?

A

because carbon dioxide in the air reacts with water to produce a mildly acidic solution
CO2 + H2O –> H2CO3
carbon dioxide + water –> carbonic acid

54
Q

what happens when the pollutant sulfur dioxide reacts with clouds? word/symbol equation?

A

it forms dilute sulphuric acid, which is quite acidic

2SO2 + O2 + H2O –> 2H2SO4

55
Q

what is the effect of nitrogen oxides being released into the atmosphere?

A

nitric acid (which precipitates as acid rain) is formed

56
Q

what are some harmful effects of acid rain? (4)

A
  1. Lakes become acidic causing plants/animals to die
  2. disrupts eco systems
  3. kills trees
  4. damages limestone buildings and stone statues
57
Q

what is cracking?

A

splitting up long chain hydrocarbons into shorter ones

58
Q

what are some properties of long hydrocarbons?

A

high boiling points, viscous

59
Q

what are some properties of shorter chain hydrocarbons in comparison to long chain ones?

A

lower boiling points, much thinner and paler in colour

60
Q

what is an example of a short-chain hydrocarbon used to make petrol?

A

octane

61
Q

what are the required conditions for cracking? (temp, catalysts, state of hydrocarbon)

A

vaporised hydrocarbons are passed over powdered catalyst at…
TEMPERATURE: 600-700 degrees
CATALYSTs: silica (SiO2) OR alumina (Al2O3)

62
Q

typically, in cracking…

long-chain alkane molecule —>

A

shorter alkane molecules + alkenes

63
Q

what two things does the long-chain dodecane, found in paraffin, thermally decompose to form in cracking?

A

octane and ethene

64
Q

are the smaller alkanes produced when cracking paraffin in the lab collected as solids of gases?

A

solids

65
Q

how are alkenes collected during the cracking of paraffin in the lab?

A

as gases they travel down the delivery tube and are collected through water using a gas jar

66
Q

when are plastics formed?

A

when small molecules called monomers react to make a polymer

67
Q

what kind of conditions are needed to make addition polymers? eg low/high pressure

A

high pressure and a catalyst

68
Q

what happens in terms of the bonds when alkenes form addition polymers?

A

the carbon-carbon double bonds open up thanks to the high pressure and a catalyst and polymerise (join hands) to form long saturated chains - polymers

69
Q

with the help of pressure and a catalyst, what addition polymer does ethane become?

A

poly(ethene)

70
Q

what is the repeat unit of a polymer and how is it represented?

A

the section of the polymer’s displayed formula that is repeated over and over again. Drawn as (repeat unit)n

71
Q

what do you do to the repeat unit in order to find the monomer that makes it?

A

add a double bond

72
Q

what properties does the polymer poly(propene) have and which of its uses depend on these?

A

tough polymer, but relatively flexible and resistant to heat… useful to make things like kettles, food containers, carpets

73
Q

what properties does the polymer poly(ethene) have and which of its uses depend on these?

A

light, stretchable polymer…. useful for making packaging: plastic bags, bottles, food containers

74
Q

most addition polymers are inert. Why Is this?

A

because the carbon-carbon double bonds in polymer chains are very strong, and not easily broken

75
Q

what property of polymers means they don’t biodegrade easily?

A

they are inert, so can’t easily be broken down by bacteria/other organisms

76
Q

what is another reason why it is hard to get rid of polymers, other than the fact they don’t biodegrade well?

A

they can’t be burnt, as this releases toxic gases

77
Q

what is the haber process used to create, and what is this used for?

A

ammonia, NH3, used to make fertilisers

78
Q

how is the nitrogen required for the haber process to occur obtained?

A

from the air, which is 78% nitrogen

79
Q

from where is the hydrogen needed for the haber process to occur obtained?

A

from natural gas, or alternatively from cracking hydrocarbons

80
Q

what are the industrial conditions needed in the haber process? (pressure, temp, catalyst)

A

Pressure: 200atm
Temperature: 450 degrees
Catalyst: Iron

81
Q

why do higher pressures favour the forward reaction in the haber process?

A

there are more moles of gas (4 times) on the left side than on the right

82
Q

what will the effect of a high pressure be on the yield of the haber process?

A

increased pressure will equal higher yield

83
Q

what is the equation representing the haber process?

A

N2 + 3H2 2NH3 (reversible reaction)

84
Q

is the forward reaction for the Haber process exothermic or endothermic? what effect does this have when the temp. is increased?

A

exothermic, means that increasing the temp. will move the equilibrium the wrong way- to the left- leading to a decrease in % yield

85
Q

what does the fact that the forward reaction in the Haber process is exothermic tell you about the optimum temp. for the reaction occur in terms of yield?

A

the yield of ammonia will b greater at lower temperatures

86
Q

why is the fact that a greater yield of ammonia is produced at lower temperatures an issue in the Haber process?

A

lower temperatures mean a slower rate of reaction - so equilibrium would be reached slowly…

87
Q

why is the temp. required for the Haber process fairly high even though lower temperatures favour the forward reaction?

A

450 degreesC is a COMPROMISE between maximum yield and speed of reaction - (it’s better to wait 20secs for a 10%yield than 60secs for a 20%yield)

88
Q

in the haber process, how is the ammonia (a gas) separated from the hydrogen and nitrogen?

A

it liquifies in the condenser and is removed - the N2 and H2 are recycled still in the form of gases as ammonia has a higher condensing temp. than the others

89
Q

what is the Otswald process used to make?

A

nitric acid(HNO3) and ammonium nitrate fertiliser

90
Q

what is needed for the Otswald process?

A

ammonia

91
Q

how is ammonium nitrate created from ammonia and nitric acid, and why does this mean it is a good fertiliser?

A

ammonia is reacted with nitric acid to make ammonium nitrate

it is a very good fertiliser because it has nitrogen from two sources - plants need nitrogen to make proteins

92
Q

why is ammonium nitrate a more effective fertiliser than organic alternatives?

A

it helps farmers produce crops from land that otherwise wouldn’t have been fertile enough

93
Q

what is poly(chloroethene) used to make?

A

clothes, pipes, insulating electrical cables

94
Q

what is the contact process used to make?

A

sulphuric acid

95
Q

what is the first stage of the contact process and what is the reaction representing this?

A

forming sulphur dioxide by burning sulphur in air or roasting sulphide ores
S + O2 –> SO2

96
Q

what is done to the sulfur dioxide produced in the 1st stage of the contact process and what does is formed? (+symbol equation)

A

it is oxidised with the help of a catalyst to form sulfur trioxide gas
2SO2 + O2 2SO3

97
Q

what is done to the sulfur trioxide produced in stage 2 of the contact process and what is formed? (+symbol equation)

A

it is dissolved in concentrated sulfuric acid to form liquid oleum
SO3 + H2SO4 –> H2S2O7

98
Q

in the final stage of the contact process, how is concentrated sulfuric acid formed from oleum?

A

oleum is diluted with measured amounts of water to form concentrated sulfuric acid
H2S2O7 + H2O –> 2H2SO4

99
Q

in the second stage of the contact, sulfur dioxide is oxidised to become sulfur trioxide gas. The equation is 2SO2 + O2 –> 2SO3. This reaction is exothermic. What is the obvious thing to do to the temp. and pressure in order to get the maximum yield? why is this a problem?

A

reduce the temp, increase the pressure (product has less moles/volume than reactants)
this is a problem because a low temp. means a very slow rate of reaction

100
Q

what are the conditions needed for the contact process? (temp, pressure, catalyst)

A

temperature: 450 degrees C
pressure: 2atm
catalyst: vanadium(V) oxide, V2O5

101
Q

what are the three main uses of sulfuric acid in modern industry?

A
  • phosphate fertilisers to improve the amount of nutrients in the soil
  • detergents
  • paints - sulfuric acid is used to make titanium dioxide which is a white pigment used in paints
102
Q

during the electrolysis of brine, what is given off at the cathode?

A

hydrogen gas

103
Q

during the electrolysis of brine, what is given off at the anode?

A

chlorine gas

104
Q

during the electrolysis of brine, what is left in solution?

A

NaOH - sodium hydroxide

105
Q

what three useful products are produced during the electrolysis of brine?

A

chlorine, hydrogen, sodium hydroxide

106
Q

what is chlorine used for?

A

to sterilise water supplies (chlorination) , to make bleach, to make HCl

107
Q

what is hydrogen useful for?

A

to make ammonia in the Haber process, to change oils into fats for making margarine

108
Q

how is sodium hydroxide useful in the chemical industry?

A

very strong base, used to make soap, bleach, and paper pulp

109
Q

what kind of polymers are made when a small molecule is released during a reaction?

A

condensation polymers

110
Q

describe condensation polymerisation

A

involves two different types of monomer. These monomers react and bonds form between them, making polymer chains. For each new bond that forms, a small molecule is lost

111
Q

what is an example of a condensation polymer and what is the small molecule lost?

A

nylon is the condensation polymer, water is lost

CHEMISTRY based on CGP (7 decks)

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