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GCSE Chemistry C1

C1 Revision Guide
by

Gerard Hobley

on 13 June 2016

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Transcript of GCSE Chemistry C1

Mars, the Red Planet.
From here the Earth is
A tiny dot.
In this revision
guide we will cover
a number of themes
and look at things
from different perspectives.
We will look at planetary processes
Welcome to GCSE Chemistry C1
In C1 there is a little planetary science (The Earth and its Atmosphere). There is some geology and topics which effect the landscape. We will consider some industrial processes. Most importantly we will learn about some of the chemistry that underlies the above and we will learn how to write about this on paper.
The Earth and
its Atmosphere

Know about the following and
apply these throughout C1
Atoms and elements
Chemical symbols, formula
The periodic table
Compounds
Physical changes
Chemical changes
Word equations
Mass of reactants = mass of products
Balanced equations
Essential chemistry
2) Green plants evolved and used CO2 to produce sugars, structural materials and O2, eventually increasing the proportion of O2 to its current level (200 million years ago, 21 %). The CO2 is used up. Now carbon is mainly left in carboniferous deposits (coal, oil, and limestone).
PANGAEA, the original land mass.
Japan gets many earthquakes. It lies at the juncture of the Pacific and Eurasian plates which are converging.
Plates slide past each other for example at San Andreas in California.
3) Oxygen allows complex animals and plants to evolve. Oxygen is extremely toxic to anaerobic species and these are mainly killed off. An ozone layer is formed in the outer atmosphere which helps protect creatures from harmful UV rays.
Why did Wegener suggest Pangaea?
When the pressure underground builds up and the plates slide suddenly, massive amounts of energy are released. This is the cause of Earthquakes
Mountain chains inland
Mountains at the coast
The lithosphere is made up of several large
areas of rock called
TECTONIC PLATES
which float on the liquid mantle.

The plates move very slowly, a few
centimeters a year, floating on the moving magma below. These are consumed as they are drawn beneath other plates in
SUBDUCTION
(see next two diagrams).
There are convection currents in mantle and outer core.
1) The molten Earth cooled forming a
crust, but large amounts of volcanic
activity gave out gasses like CO2 and methane. As the Earth cooled the oceans condensed and an atmosphere of mainly
CO2 formed. Any life is anaerobic.
How has the atmosphere changed?
Volcanoes are thought to be responsible for the early atmosphere (nearly 4.5 billion years ago).
The atmosphere then consisted mainly of;
The atmosphere
As the earth cooled it shrank and the crust
distorted to allow for this?

This theory was popular until 1915 when Alfred
Wegener put forward the theory of the
continental drift.
Where do mountains come from?
Diagram of Earth
With a section cut away
There are 4 main layers
Table showing some features of the Earths main layers.
Diagram showing convection currents
When plates move
World map showing the major continental plates and their current movement.
This is the San Andreas Fault
San Fransisco
Globally there are many earthquake zones
Map showing earthquake zones and volcanoes
At some point in the Earths history there was one giant super-continent which has been named Pangaea.
Africa
Latin America
North America
Eurasia
India
The Planet Earth
Has 4 layers
The solid crust floats upon the semi-liquid mantle
The core is mainly metallic with an inner and outer
The crust is composed of TECTONIC PLATES
These move on convection currents in the mantle and outer core
When the plates move they cause earthquakes
less dense molten rock sometimes forces its way to the surface causing volcanoes
There are two additional layers; the ocean and atmosphere
The Earths atmosphere has sometimes been described as "a thin blue line."
As you can see the Atlantic Ocean is
expanding and the Pacific contracting
Carbon dioxide
Water vapour
Ammonia
Methane.
3 phases
Products from Rocks
Limestone Quarry
Diagram of cement production
Disadvantages
There is a lot of limestone.
Limestone, marble and chalk.
Limestone is ubiquitous and therefore cheap.
This makes it an excellent material for industrial processes.
It is used directly in buildings and roads.
It is also altered chemically and used in a number of industrial processes.
Be able to discuss issues around the quarrying and use of limestone.
be able to discuss the chemistry of carbonates.
be able to discuss the properties of materials and how these relate to their uses.
A quick recap
limestone is also used in glass production.
Sand, limestone and sodium carbonate are heated together.
These fuse into glass.
Glass is also an excellent building material.
It is relatively brittle.
Used mainly in windows for buildings.
Has excellent insulation properties.
Is used extensively when spun out into glass wool for this purpose.
Glass
By using steel rods
Reinforced concrete is an excellent building material
Allows the construction of large and complex structures like bridges.
These can be precast and assembled in situ.
How is concrete reinforced?
Increased employment
Increased local trade brings money to the area
Potential future development of recreation areas (lakes for water sports, crags for rock climbing)
The limestone benefits society in the products derived from it (cheap housing, roads, glass, steel).
As a resource it is incredibly cheap.
How do we use limestone today?
Calcium carbonate (CaCO3) was deposited on the sea bed mainly during
the carboniferous and is made up of the fossilised bodies of plankton
(foraminifera) or corals which secrete calcium carbonate skeletons. It
formed massive beds or reefs which have been pushed up from the seabed
over time.
Today limestone is the underlying rock of some spectacular scenery
Therefore it is ubiquitous and cheap.
It makes some striking landscapes.
Yorkshire Dales, White Peak Area, Karst Areas
of South China or the Tropics. Rivers can become subterranean (pot holes). Limestone reacts with acid giving off CO2 plus water. This leads to much of the weathering of limestone we observe. CaCO3 +
2HCl = CaCl2 + CO2 + H2O (could be acid rain or natural carbonic acid, CO2 + H2O = H2CO3)
Remember the chemistry of carbon-ates.
What happens:
When you heat limestone (remember group 1 carbonates behave differently)?
When you take quicklime and add it to water?
When you bubble carbon dioxide through a solution of calcium hydroxide?
Be able to draw word, symbol and balanced chemical equations for these processes.
Quarrying and using limestone
Advantages
Noise
Eyesore
More traffic
Air pollution (dust and exhaust fumes)
Natural wild life habitats destroyed
High energy requirement of processing
CO2 from lime production/global warming
Limestone is the earths major carbon sink.
Diagram of a lime kiln
Limestone can be used directly as a building material
Huge quantities are used
as ballast for roads
and railways
Or it can be used in chemical processes
Cement is mixed with other materials
and used extensively in the
construction industry (concrete, mortar).
Copper mining
in Africa
Which will rust?
Pure metals (all atoms the same
size) are therefore softer
Basic oxygen process


2PbO + C = CO2 + 2Pb

Which is oxidised?

Which is reduced?
For the following reaction
Iron oxide is reduced by carbon monoxide to
give iron and carbon dioxide.
The calcium carbonate removes impurities.

Fe2O3 + 3CO = 2Fe + 3CO2

Oxygen atoms are removed from the iron
oxide (reduction).

Zinc, iron, tin, lead, copper etc can be extracted from their ores (usually oxides) by reacting with carbon.

Oxygen is lost from the ore therefore this is called
Metals below carbon
in the reactivity series
Extraction of metals
Extraction of metals
Metals are obtained from their compounds
(salts) called metal ores, which contain
enough metal to make extraction
economically viable (worth doing).

The method of extraction depends on the
position of the metal in the reactivity series
Extraction of metals from rocks
By keeping out
air or water
(oil, painting);
alloying and
sacrificial prot-
ection are other
methods.
We prevent rusting
Types of steel
Atoms of different elements distort the layers of iron atoms making the alloys harder.
Iron is combined with various metals
(chromium, cobalt, manganese, nickel,
tungsten and vanadium) or carbon to
produce steel alloys with varying
properties depending on the mixture.
Alloys of iron (steels)
OXIDATION
REDUCTION
Metal oxide + carbon carbon dioxide + metal
Videos on aluminium
and copper extraction
www.rsc.org/Education/
Teachers/Resources/Alchemy/
Index2.htm


Titanium has similar properties to
Aluminium but is resistant to corrosion.
In the furnace the iron is molten and dense therefore runs to the bottom where it is run off into channels scraped into sand, called pigs. This is pig iron (cast iron) which containing 4% carbon. It is very brittle and the uses are limited.
Pig iron
Metal Reactivity
Series
A more reactive metal will corrode in
preference when attached to a less reactive
Metal.
Magnesium is attached
to the iron hull of a ship

Galvanising uses zinc
to protect iron
Sacrificial protection
What conditions are needed for rusting?


Water
Air

(salt speeds
up the
the rusting
process)
Corrosion (or rusting for iron only)
Pig iron is mixed with scrap iron and pure
oxygen passed through, oxidising the
impurities. Calcium carbonate is then added
to remove the acidic oxides.
This leaves pure iron which
is very soft (malleable) and
not suitable for many
functions.
Basic oxygen process
Have properties similar to other metals and are
therefore very useful. For example iron, titanium
and copper.
Transition metals
Silver, Gold, Platinum
PHYSICAL EXTRACTION
Zn, Fe, Sn, Pb, Cu
BLAST FURNACE (heating with carbon to reduce their oxides)
Potassium, Sodium, Calcium, Magnesium, Aluminium
ELECTROLYSIS
Reactivity Series
The least reactive metals are found “native”
i.e. as free metals.
Extraction of metals
One problem is that metallic materials in recycled objects are often mixtures of different metals. This can mean that obtaining pure metals from recycling is more expensive, as
it may use more electricity than extracting metals from ores.
Recycling costs less than extracting metals and can be profitable.
Metals are easier to recycle than plastic and they retain their original properties, such as conductivity and hardness.
Recycling uses up to 95% less electricity than producing metals from ores.
Recycling creates less waste and reduces the number of
sites that have to be mined.
Phytomining uses plants to absorb metals from the soil. The process can be used to clean contaminated land. Treating the plants with certain chemicals increases their ability to accumulate minerals in their cells.
Leaching uses less electricity than traditional mining and does not produce waste gases. Copper ores are treated with and dissolved in dilute sulphuric acid, producing copper sulphate. Electrolysis is then used to extract the copper. Certain bacteria can also be used to dissolve ores and form copper sulphate.
New mining techniques can decrease the effects of metal extraction on the environment.
Copper mining: global copper deposits
are becoming scarce
Extraction, especially electrolysis, also uses lots of electricity.
Harmful waste gases, including sulphur dioxide, carbon dioxide and carbon monoxide, are produced by extraction.
Open-cast mining removes ores using explosives. It produces dust and can scar the landscape. This disused copper mine in Ajo, Arizona, measures one mile wide.
Extracting metals causes huge amounts of waste. Copper production discards 99.5% of the extracted ore.
stage to remove the impurities and obtain pure copper.
Only pure copper can be used for electric wires. Even a very low level of impurities will reduce copper’s conductivity.
The copper extracted from compounds by reduction with carbon is impure. Electrolysis is actually used at this
Copper is an excellent conductor and does not corrode quickly. These properties make it a good material for wiring and plumbing.
Copper is not very reactive and
can occur native but it is rare to
find pure copper. Usually, it is found combined with other elements, such as in the ore malachite.
Electrolysis is expensive and so it is only used to extract reactive metals that cannot be extracted in other ways.
+
aluminium oxygen
aluminium oxide
Aluminium is a reactive metal that is found in the ore bauxite. It is combined with oxygen as aluminium oxide. Electrolysis is used to remove the oxygen and extract aluminium, which means that reduction takes place.
Electrolysis is a process that uses electricity to separate the elements in a compound. The word electrolysis means ‘splitting with electricity’.
The mined material is treated to concentrate the
metal rich ores. Often this involves a mechanical
process separating on the basis of density or
some other property of the ore. This makes the
extraction process simple and less costly
(economically and energetically).
The more reactive metals are the most
difficult to extract . The ore has to be
first melted and then purified by
electrolysis.
silver gold platinum
reduction.
Blast furnaces are used for the reduction of many metals with carbon. This is a diagram of one used for iron production.
Iron production
A Quick Reminder
Metals fit within a reactivity series.
More reactive metals can displace less reactive metals from their compounds.
Carbon and Hydrogen also fit into this series.
Metals below carbon in the series are removed from their ore by reduction with carbon.
More reactive metals are reduced using electrolysis.
Be able to relate the properties of metals to their uses.
Be able to draw word and balanced symbol equations for all the above.
products from oil
This is a picture of a North Sea
oil rig
Mostly alkanes such as methane C 1 H 4
ethane C 2 H 6
propane C 3 H 8
butane C 4 H 10
pentane C 5 H 12

General formula CnH2n+2
What are the hydrocarbons in oil?
www.rsc.org/Education/Teachers/Resources/Alchemy/Index2.htm

in your own time look at www.bbc.gcsebitesize/science/aqa/crudeoil and substancesfromcrudeoil
How are oil and gas transported?

Alkanes contain only single bonds and are
therefore said to be saturated
First 5 alkanes
In the laboratory, describe
Of hydrocarbons

(Organic compounds consisting of mainly
carbon and hydrogen atoms bonded
together)
The mixture is separated by a physical
process called fractional distillation
A mixture
The substances contained in a fraction have similar boiling points because the hydrocarbon chains are a similar length.
The longer the hydrocarbon chain, the higher the boiling point.
The shorter the hydrocarbon chain, the
lower the boiling point.
Why do the different fractions separate?
By fractional distillation
How can we separate the mixture?
A well is drilled so
that the crude oil and
other liquids travel
up the bore hole.
When it comes to the
surface the crude oil
has to be moved
closer to where it is
needed.
How do we get oil and gas out of the ground?
Activity
C19H40
C31H64
C16H34
C12H26

B.Pt
(oC)
No. Carbon atoms 
The boiling points of molecules
Structural formula
Alkanes
propane, C3H8
H
H
H
C
H
H
C
H
H
H
C
ethane, C2H6
H
H
H
C
H
H
H
C
methane, CH4
H
H
H
H
C
How are Fossil fuels (coal, oil and gas) formed?
cracking
cracking
In the above what would we expect to see and what would we use as control experiments?

Alkanes contain only single bonds and are
therefore said to be
saturated
In the laboratory, describe
www.rsc.org/Education/Teachers/Resources/Alchemy/Index2.htm

in your own time look at www.bbc.gcsebitesize/science/aqa/crudeoil and substancesfromcrudeoil
How are oil and gas transported?
Another name for a hydrocarbon “family” is
a homologous series (eg alkanes and alkenes)

In a homologous series, the molecular formula of each consecutive member increases by - CH 2 -
Hydrocarbon “families”
Alkenes have general formula
CnH2n


They contain a double bond and are therefore
said to be
UNSATURATED
Alkenes
During cracking, another type of
hydrocarbon is produced called an alkene

C10H22 = C8H18 + C2H4

alkane alkane alkene (ethene)
Cracking
The longer chain products from oil are more difficult to burn than the shorter chain products and there are more of them.

The alkane hydrocarbons are heated to a vapour and passed over a hot catalyst where they break down to shorter chain alkanes. This is called
CRACKING
.

This is an example of thermal decomposition.
Cracking
Evidence? Graph showing yearly deviation from the average (1920-2005)
Global dimming
Global warming
Acid rain
To help prevent these low sulphur fuel is produced for petrol in cars and catalytic converters try to remove unburned hydrocarbons. In power stations acidic impurities are removed using calcium carbonate.
What are the environmental effects of burning all this fossil fuel?
In plenty of oxygen
Mostly alkanes such as
methane C 1 H 4
ethane

C 2 H 6
propane C 3 H 8
butane C 4 H 10
pentane C 5 H 12

Or with much longer carbon chains with the
general formula
CnH2n+2
What are the hydrocarbons in oil?
Alkanes
The substances contained in a fraction have similar boiling points because the hydrocarbon chains are a similar length.
The longer the hydrocarbon chain, the higher the boiling point.
The shorter the hydrocarbon chain, the
lower the boiling point.
Why do the different fractions separate?
By fractional distillation
How can we separate the mixture?
That is organic compounds consisting of mainly
carbon and hydrogen atoms bonded
together. The mixture is separated by a physical
process called fractional distillation.
Crude oil is a mixture of hydrocarbons
CH4 + 2O2 = 2H2O + CO2
and a formula equation


Methane + oxygen = water + carbon dioxide
A word equation for complete combustion of methane
Hydrocarbons are generally used as fuels because they burn easily in air.
C19H40
C31H64
C16H34
C12H26

B.Pt
(oC)
No. Carbon atoms 
A well is drilled so
that the crude oil and
other liquids travel
up the bore hole.
When it comes to the
surface the crude oil
has to be moved
closer to where it is
needed.
How do we get oil and gas out of the ground?
They get trapped where
the rocks are folded
into an umbrella
shape with a porous rock
beneath an impervious rock.
Oil and gas are found in underground pockets.
of ful
Global
Warming

*Polar ice
caps melt
*Floods
*Deserts
increase
What effect do these gases have on the earth?
Hexane, C6H14
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
pentane, C5H12
H
H
H
C
H
H
C
H
H
C
H
H
H
C
butane, C4H10
Structural formula
propane, C3H8
H
H
H
C
H
H
C
H
H
H
C
ethane, C2H6
H
H
H
C
H
H
H
C
methane, CH4
H
H
H
H
C
See the following video clips
Graph showing the boiling points of hydrocarbon molecules
Number of carbons in the chain
Boling point
The different fractions of hydrocarbon obtained have different properties. Boiling point, viscosity, colour etc.
CnH2n+2
if C = 12
H = (2 x 12)+2
Yes- Contains less saturated fat therefore
helps weight control

No - During manufacture trans-fats are
produced which increase cholesterol
levels in the blood
Is margarine good for you?
Plant oils from fruits, seeds and nuts can
also be used to provide energy as both
fuels and in food.

eg rape seed oil
Plant oils
As with all carbon based fuels, ethanol burns in air to produce carbon dioxide.

C2H5OH + 3O2 = 2CO2 + 3H2O

Ethanol is also made by fermentation however getting the ethanol into a form which can be burned efficiently requires energy inputs from distilling it etc.
Ethanol as a fuel
Sugars in the presence of yeast ( enzyme)
react to from ethanol and carbon dioxide.
yeast
Sugar = ethanol + carbon dioxide

Be able to compare the effects of the 2 methods of
making ethanol on the environment.
Fermentation

When we react ethene with steam in the presence of a catalyst, the double bond is broken and we make ethanol. Water adds across the double bond.
Reaction of ethene with steam
landfill
Goretex
Shape memory polymers
Low density polythene
explain polymerisation
predict the reactions of alkenes and the uses of products made from alkenes. Therefore you should know the chemistry of alkenes (addition of bromine water etc)
describe the extraction of plant oils
describe the use of emulsifiers and additives in food
describe the use of plant oils as a source of energy (fuel and food)
always remember the underlying chemistry
You should be able to:
Hydrogen is added across the double bond

60 o C
CH2=CH2 + H 2 = H3CCH3
nickel

unsaturated saturated
Making margarine (hardening)
Plant oils contain long chain molecules
which are unsaturated (poly-unsaturated contain many double bonds, mono-unsaturated contain only one double bond per molecule).
Margarine is a plant oil which has been solidified chemically
Back to plant oils
Look at packaging
and find E numbers
Food packaging
Emulsifiers increase the thickness of
liquids making them easier to handle, make
them smoother and improve appearance
eg chocolate.
The droplets of oil are suspended in the
water.
The negatively-charged heads repel each
other keeping the emulsion stable.
The emulsifier molecules cluster around
the oil droplets, tails inwards and heads
outwards forming micelles
micelles

Crushing and then pressing
OR heating with steam (distillation).
The water and any impurities are then
removed.
How do we get oils from plants?
Fermentation
There are problems associated with the disposal of
polymer waste?
* most polymers are not biodegradable
* burning causes toxic fumes
* additionally this is fossil carbon which has not been converted into atmospheric CO2
* disposal uses landfill

* recycling includes use of burning plastics to produce energy
Waste disposal
Polymers such as nylon are made by
reaction 2 different monomers. During the
reaction water is removed.

A + B + A + B + A + B = ABABAB + water

monomers polymer
Condensation polymerisation
Scientists constantly work on the improvement of existing and on new types of polymer. These have diverse applications in such things as;
Waterproof coatings.
Dental polymers
Wound dressings
Hydrogels
Smart materials, etc.
New developments in polymer technology
Rubber can be made stronger by the
addition of sulphur creating bridges between
the rubber molecules
Vulcanised rubber
The properties of the polymers can be
varied by changing the groups in the ethene
structure

Such as PVC and PTFE (Teflon)
Different polymers (plastics)
polythene
The double bond in an alkene can be “opened” to make a polymer.

Many single units or
MONOMERS
, join together to form very large molecules as long chains. This type of molecules is called a polymer.
Addition polymerisation
Plant Oils and Polymers
Sunflower oil and oilseed rape are used to
make biodiesel.
Plant oils as fuels
The liquid oil becomes more viscous giving
a product which spreads easily.




The properties can be varied by changing
the amount of hydrogen.
Properties of margarine
A range of other additives are added to processed
food.

they:
"Improve" taste (flavour enhancers)
Extend shelf life (preservatives and anti-oxidants)
"improve" the appearance (dyes etc)
Lists of additives are included on the packaging.

Overexposure to certain food additives may cause health problems.
Other food additives
We can make oil and water miscible by
adding emulsifiers.

Emulsifiers have a molecule with a long
hydrocarbon chain which likes oil and a head
which likes water.

Detergents and soap are emulsifiers.
emulsions
They are Immiscible



oil
is less dense than
water
Oil and water do not mix
Alcohol can be used on its own or added to
petrol, giving
GASOHOL.
This burns more
cleanly than pure
petrol and
uses less oil.
Alcohol as a fuel
Burning plastic waste (incinerator)
Thermosoftening (thermoplastic ) plastics melt
when heated therefore they can
be recycled easily.

Thermosetting plastics are hard and rigid, and
do not melt when they are reheated. They are difficult to recycled.

The difference in properties is due to cross
linking between the molecules.
Thermosetting and thermosoftening
Many foods are mixtures
of oil and water
eg ice cream
salad dressing
milk
Emulsifiers in food
High density polythene, closer packing of
Molecules, stronger. Polymers are engineered to suit their use.
Different types of polythene
Fawley Oil Refinery near Southampton
In oil refineries crude oil is converted into fuels and a range of chemical feedstocks such as alekenes. These are then used in a range of industrial processes.
Used in stitches for wound repairs.
An oil seed rape field.
Remember
It is thought that all the oil (like calcium carbonate) was originally atmospheric CO2.
Burning it causes a range of problems which you should be able to discuss.
The global economy as it is, is almost entirely dependent upon burning fossil fuels.
Alternatives are being investigated for example carbon neutral fuels where the carbon is assimilated from atmospheric CO2, or hydrogen as a fuel.
As we pan away through the dark void of space we should take time to remember our journey.
We looked at the Earth. About tectonic plates floating on a sea of molten rock.
We saw how the atmosphere has changed over billions of years through the activity of tiny animals and plants.
We looked at the fossilised bodies of some of these creatures in calcium carbonate. We described how modern man takes advantage of the plentiful supply of this rock.
We investigated metals, their extraction and uses.
We looked at the activities of the petrochemical industry
And finally we looked at plant derived materials

Thankyou for travelling along this road of discovery and good luck in your exams to follow..............GH
Full transcript