Notesale: Turn your study into money

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2
...
g
...
g
...
This is because Na +
and Cl- have fewer charges than Mg2+ and O2-, and Na+ ions are larger than Mg2+ ions
and cannot get as close to the negatively charged ions
...
g
...
g
...


1

Ionic bonding
•

moved electrons

Covalent bonding
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shared electrons

Diamond

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•
•
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contains strong covalent bonds, where each carbon is bonded to four others, forming a giant
covalent structure
high melting point (a result of the strong covalent bonding present)
hard, brittle, does not conduct electricity (because there are four bonds)

Graphite

•
•
•
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contains strong covalent bonds, where each carbon is bonded to three others, forming
layers than can slide over each other
high melting point (a result of the strong covalent bonding present)
soft, greasy, conducts electricity (because there is a fourth ‘delocalised’ electron

Graphene
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shown to be the strongest material ever tested and the best electrical conductor, but,
although claims have been made that it will transform technology in the future, there are, as
yet, no commercially available 'graphene products'
...


Bulk materials
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do not have the same properties as individual atoms, as demonstrated by diamond,
graphite, fullerenes, carbon nano-tubes and graphene having different properties despite all
containing only carbon atoms and by nano-scale silver particles exhibiting properties not
seen in bulk silver

3

Nano-scale particles of silver
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antibacterial, antiviral and antifungal
used in plasters, antiseptic sprays, refrigerator linings, socks and deodorant sprays

Nano-scale particles of titanium dioxide
•
•
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•
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absorb and reflect UV light, but are also transparent so appeal to users
used in some sun screens
catalyse the breakdown of dirt in the presence of UV light
cause water to spread out in a thin film rather than form droplets on the surface
used in self-cleaning glass

The possible risks associated with the use of nano-scale particles of silver and titanium
dioxide, and of potential future developments in nanoscience
•

•

•

Nanomaterials currently used have been tested to ensure that they cause no
damage to individuals or the environment, but that their long-term effects are as yet
unknown
...

While it has been shown that these uses are safe in the short term, there is no
certainty that exposure over many years will not result in problems
...
g
...
2: Acids, bases and salts

Substances
•
•
•

either acidic, alkaline or neutral
either strong or weak
either concentrated or dilute

The pH scale

•

Acids
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a source of H+ ions

Alkalis
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a source of OH- ions

Bases
•
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metal oxides and metal hydroxides
An alkali is a soluble base
...


The reactions of dilute acids with metals
•
•

produce a solution of the metal salt and hydrogen gas
The higher the metal in the reactivity series, the quicker it reacts with the dilute acid
...

tests for acidic substances and CO23- ions

The salt formed by hydrochloric acid
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chloride

The salt formed by nitric acid
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nitrate

The salt formed by sulfuric acid
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sulfate

The salt formed by ethanoic acid
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ethanoate
7

The test used to identify SO42- ions
•
•

White precipitate forms when barium chloride solution is added to a sulfate
...

2
...

•
•

CuO(s) + H2SO4(aq) → CuSO4 + H2O(l)
excess base/carbonate to use up all acid
filtration to remove excess base/carbonate
evaporation of water to form crystals
Small crystals can be formed quickly by heating to evaporate until about 1/3 of the
solution remains and leaving to cool
...


The preparation of insoluble salts by precipitation reactions
•
•
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involves two soluble salts reacting together
The precipitate can be filtered, washed with water on the filter paper and then dried
in an oven
...


Titration
•
1
...

3
...


a method to prepare solutions of soluble salts and to determine relative and actual
concentrations of solutions of acids/alkalis
indicator and fixed volume of acid/alkali in flask
exact volume of acid/alkali needed for neutralisation measured and recorded
same fixed volume of acid/alkali in clean flask and exact volume of alkali/acid
needed for neutralisation added but with no indicator
evaporation of water to form crystals

Concentration
•

concentration (M or mol/dm3 ) =

mass (g)
molar mass (Ar or Mr)

Moles
•

number of moles =

mass (g)
molar mass (Ar or Mr)

8

×

1000
volume (cm3 )

2
...
g
...
g
...
g
...
g
...


Displacement reactions as demonstrated by an iron nail in copper(II) chloride solution
•
•
•

copper(II) chloride + iron → iron chloride + copper
CuCl2 + Fe → FeCl2 + Cu
Iron is higher than copper in the reactivity series, so iron displaces copper
...


Reduction

Oxidation

•

•

the removal of oxygen

the gain of oxygen

The industrial extraction of iron
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continuous, with new raw materials added and products removed all the time due to the
time and cost associated with getting the furnace up to temperature
use the raw materials of iron ore, coke (as a fuel), limestone and hot air

Iron ore
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source of iron

Coke (as a fuel)
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produces carbon monoxide for the reduction

Limestone
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removes impurities (slag formation when limestone breaks down and reacts with sand from
the rocks)

Hot air
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provides oxygen so that coke can burn
10

Combustion reactions demonstrated by the combustion of carbon (Stage 1)
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The coke (carbon) is burnt to form carbon monoxide
...

iron(III) oxide + carbon monoxide → iron + carbon dioxide
Fe2O3 + 3CO → 2Fe + 3CO2

Decomposition reactions demonstrated by the decomposition of calcium carbonate (Stage 3)
•
•
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The limestone (calcium carbonate) decomposes in the heat to form calcium oxide
...

calcium oxide + silicon dioxide → calcium silicate
CaO + SiO2 → CaSiO3

Transition metals
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•
•
•
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found in the centre of the Periodic Table
mostly useful catalysts (such as iron in the manufacture of ammonia and platinum in
catalytic converters)
can form more than one type of ion (such as Fe2+ and Fe2-)
have coloured compounds
display typical metallic properties

Alloys
•
•
•

mixtures made by mixing molten metals
properties can be modified by changing their compositions
e
...
Steel is much harder and stronger than iron and is therefore more useful
...


11

The identification of ions by their precipitation reactions with OH•
•
•

Cu2+
Fe2+
Fe3+

(blue):
(pale green):
(brown):

Cu2+(aq) + 2OH-(aq) → Cu(OH)2(s)
Fe2+(aq) + 2OH-(aq) → Fe(OH)2(s)
Fe3+(aq) + 2OH-(aq) → Fe(OH)3(s)
Aluminium
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Steel (iron and carbon)
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used in food and beverage cans
used in pipelines
hard
strong

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used in aerospace industry
used in high-voltage power lines in the
National Grid
strong
low density
good conductor of heat and electricity
resistant to corrosion

Titanium
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•
•
•
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•

Copper

used in artificial hip joints
used in fighter air craft
hard
strong
low density
resistant to corrosion
high melting point

•
•
•
•
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used in plumbing
used in electrical wiring
very good conductor of heat and
electricity
malleable and ductile
attractive colour and lustre

Factors that affect the siting of plants
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near the coast, for the importing of raw materials and not for the export of products
away from built-up areas
in a town or city within commuting distance to accommodate the workforce
has good transport links for transporting the product to buyers
has a direct electricity supply (a power station close by) in the case of aluminium

Aluminium production
•

•

•

The energy costs associated with aluminium production are very high, and when Wylfa Power
Station was decommissioned, Anglesey Aluminium closed
...
Without a power station close
by guaranteeing the direct supply of electricity, this became unsustainable and the plant closed
...
Using raw materials from Wales is not sustainable on
an economic (cost) or environmental (quarrying) basis
...
Recycling aluminium requires approximately 5% of the energy used to extract the metal
from bauxite
...


12

The electrolysis of molten ionic compounds
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•
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Compounds must be melted to release their ions
...

e
...

lead(II) bromide:
cathode: Pb2+ + 2e- → Pb
anode: 2Br → Br2 + 2ePb2+ ions are reduced because they gain electrons, and
Br- ions are oxidised because they lose electrons
...

cathode: Al3+ + 3e- → Al
anode: 2O2- → O2 + 4eThe oxygen formed reacts with the carbon anodes, forming carbon dioxide gas and
requiring these to be replaced frequently
...

The volume of hydrogen formed is twice that of oxygen because there are twice as
many hydrogen atoms that oxygen atoms in a water molecule
...

Metals lower than hydrogen in the reactivity series are formed at the cathode
...
g
...

cathode: Cu2+ + 2e+ → Cu
anode: 2Cl- → Cl2 + 2ee
...
When sodium chloride is electrolysed, the products are hydrogen gas (as sodium
is above hydrogen in the reactivity series) and chlorine gas
...
g
...
A metal pan is connected to the
cathode
...


Electrolysis in the purification of copper
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Both electrodes are made from copper
...


Electrolysis in the manufacture of sodium hydroxide
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The electrolyte is sodium chloride solution
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A solution of sodium hydroxide is formed
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14

2
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g
...


Endothermic reactions
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results in a temperature decrease, as energy is taken in from the surroundings
e
...
electrolysis

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Less energy is released in forming bonds than breaking bonds
...

If the value for energy change is negative, the reaction is exothermic
...
5: Crude oil, fuels and organic chemistry

Hydrocarbons
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compounds that contain carbon and hydrogen only

Carbon chains
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formed by carbon atoms that have the ability to form bonds with other carbon
atoms

Crude oil
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•

a complex mixture of dozens of hydrocarbons with carbon chains of varying lengths
formed over millions of years from the remains of simple marine organisms

The fractional distillation of crude oil
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Crude oil is boiled/vaporised before it enters the fractioning column
...


Fractions
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mixtures containing hydrocarbon compounds that have similar boiling points and
similar chain lengths

The uses of fractions
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petroleum gases:
gasoline/petrol:
naphtha:
kerosene:
diesel:
lubricating oil:
fuel oil:
bitumen:

bottled gas
fuel for cars
making chemicals
aircraft fuel
fuel for cars, lorries and buses
lubricant for engines and machines
fuel for ships and power stations
road surfacing and roofing

16

The effect of chain length on fractions’ boiling point
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The longer the chain lengths, the higher the boiling point
...


The effect of chain length on fractions’ viscosity
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The longer the chain lengths, the more viscous
...


The fire triangle
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oxygen, heat and fuel

How to remove oxygen from the fire triangle
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water
a carbon dioxide fire extinguisher
a fire blanket

How to remove heat from the fire triangle
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water
a carbon dioxide fire extinguisher
turning of electricity

How to remove fuel from the fire triangle
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creating a gap between fire and further fuel

17

The global economic and political importance and social and environmental impact of the oil
industry
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•

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Burning fuels causes global warming and acid rain, which of course don’t only affect
the countries using the energy
...

Growing demand drives prices upwards, affecting individuals’ heating and travel
costs but also indirectly causing inflation (such as in food prices)
...


The combustion of hydrocarbons and other fuels
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requires oxygen (from the air)
produces carbon dioxide and water
exothermic

The determination of the amount of energy released by a fuel
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burning four different alcohols and comparing the amount of energy they give off
alcohol + oxygen → carbon dioxide + water

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energy released from alcohol per gram (J) =

mass of water (g) × temperature increase (°C) × 4
...


Alkanes
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have single bonds between carbon atoms
(said to be) saturated
CnH2n+2

Alkenes
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contain a double covalent bond between two carbon atoms
(said to be) unsaturated
CnH2n

Prefixes
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•
•
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meth-: one carbon
eth-: two carbons
prop-: three carbons
but-: four carbons
pent-: five carbons

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Isomers
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molecules with the same molecular formula but different structural arrangements

Structural isomers of C4H10
butane

2-methylpropane

•

Structural isomers of C5H12
pentane

2-methylbutane

•

But-1-ene and but-2-ene
but-1-ene

but-2-ene

•

20

2,2-dimethylpropane

The addition reaction of alkenes and hydrogen
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involves addition of two atoms across the C=C bond
from an unsaturated alkene compound
forms a saturated alkane

The addition reaction of alkenes and bromine
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involves addition of two atoms across the C=C bond
from an unsaturated alkene compound
forms a saturated, colourless bromoalkene

Bromine water in testing for alkenes
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safer and easier to handle than bromine
turns from orange/brown to colourless

Monomers
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small, reactive molecules
can be joined together to make a polymer

Polymerisation
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monomers joining together to make polymers
The reactivity of a monomer arises form the presence of its double bond
...


21

General properties of plastics
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flexible
strong
good thermal insulators
good electrical insulators
resistant to corrosion
low density
do not rot

Uses of polythene
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bags
plastic bottles

Uses of poly(propene)
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ropes
crates

Uses of poly(vinylchloride)
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drain pipes
window frames

Use of poly(tetrafluoroethene)
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non-stick pans

The environmental issues relating to the disposal of plastics
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Disposing of plastics in landfill is not desirable because these sites are rapidly being
filled and any plastic items will not decompose for hundreds of years
...

Recycling waste plastic reduces the amount of waste either ending up in landfill or
being burned
...


22

Yeast
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contains an enzyme that breaks down sugar, making ethanol and carbon dioxide

Fermentation
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glucose → ethanol + carbon dioxide
C6H12O6 → 2C2H5OH + 2CO2
works best at 37°C
a slow process
Fermentation products are distilled to produce spirits (such as whisky)
...


Acidified potassium dichromate(VI) in testing for alcohols
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changes from orange to green in the presence of an alcohol
an unpleasant reagent to use
the basis of a previously-used breathalyser test

Health problems associated with alcohol misuse
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liver damage
ulcers
high blood pressure

Social problems associated with alcohol misuse
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drink-driving
anti-social behaviour
aggressiveness

Advice regarding ‘healthy’ drinking limits
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has recently changed
The recommended maximum number of units of alcohol that should be consumed per week
was reduced to 14 for men and women
...

A significant amount of public money is spent each year in treating alcohol-related illnesses
and in dealing with various other issues resulting from alcohol abuse

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