C2 Chemical Resources

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C2 Chemical Resources
OCR Gateway Additional Science
W Richards The Weald School
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Fundamental Concepts
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Chemical formulae
The chemical formulae of a molecule or compound
is simply a way of showing the ratio of atoms in
it. For example
sodium chloride (NaCl)
potassium iodide (KI)
potassium nitrate (KNO3)
K
N
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Chemical formulae

• Try drawing these
• Water H2O
• Carbon dioxide CO2
• Calcium sulphate CaSO4
• Magnesium hydroxide Mg(OH)2

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Naming compounds
Rule 1 If two identical elements combine then
the name doesnt change
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Naming compounds
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Naming compounds

1. Potassium hydrogen oxygen
2. Lithium hydrogen oxygen
3. Calcium hydrogen oxygen
4. Mg(OH)2

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Naming compounds
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Simple formulae to learn
NaCl CaCl2 MgO HCl NaOH Ca(OH)2 CaCO3 HNO3 H2SO4 M
g(OH)2 Na2CO3 MgCl2
Sodium chloride Calcium chloride Magnesium
oxide Hydrochloric acid Sodium hydroxide Calcium
hydroxide Calcium carbonate Nitric acid Sulphuric
acid Magnesium hydroxide Sodium
carbonate Magnesium chloride
H2O CO2 NH3 H2 O2 N2 K2SO4 Cl2 KCl CuO (NH4)2SO4
Water Carbon dioxide Ammonia Hydrogen Oxygen Nitro
gen Potassium sulfate Chlorine Potassium
chloride Copper oxide Ammonium sulfate
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Simple chemical reactions
Water
H2O
Magnesium sulphate
MgSO4
Notice that the number of atoms on each side of
the equation is the same!
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Balancing equations
Consider the following reaction


This equation doesnt balance there are 2
hydrogen atoms on the left hand side (the
reactants and 3 on the right hand side (the
products)
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Balancing equations
We need to balance the equation


Now the equation is balanced, and we can write it
as
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Some examples
2 2 2 3
2 2 2 2 3
2 2 2 2 2 4
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Bonding Introduction







Hi. My names Johnny Chlorine. Im in Group 7,
so I have 7 electrons in my outer shell
Id quite like to have a full outer shell. To do
this I need to GAIN an electron. Who can help me?
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Ionic Bonding
04/11/2013
Here comes my friend again, Sophie Sodium
Hey Johnny. Im in Group 1 so I have one
electron in my outer shell. Unlike Harry, this
electron is far away from the nucleus so Im
quite happy to get rid of it. Do you want it?
Okay
Now weve both got full outer shells and weve
both gained a charge. Weve formed an IONIC
bond, which is basically caused by the attraction
between our charges.
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Covalent Bonding
04/11/2013
Here comes another one of my friends, Harry
Hydrogen
Hey Johnny. Ive only got one electron but its
really close to my nucleus so I dont want to
lose it. Fancy sharing?
Now were both really stable. Weve formed a
covalent bond.
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Balancing ions
04/11/2013

• Determine the formula of the following compounds
• Sodium chloride
• Magnesium oxide
• Magnesium chloride
• Ammonium chloride
• Sodium sulphate
• Sodium oxide

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Atom, molecule or ion?
Are the following things atoms, molecules or ions?

1. H2
2. NH3
3. Cl-
4. K2SO4
5. Au
6. CO32-
7. Na
8. CO2
9. H
10. H2O

1. Molecule
2. Molecule
3. Ion
4. Molecule
5. Atom
6. Ion
7. Atom
8. Molecule
9. Ion
10. Molecule

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C2a The Structure of the Earth
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The Structure of the Earth
Scientists have learnt this by studying seismic
waves (earthquakes) as the crust is too think to
drill through.
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Movement of the Lithosphere
The Earths LITHOSPHERE (i.e. the _______) is
split up into different sections called ________
plates
Words radioactive, crust, convection, tectonic,
year
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Plate Movements
Magma
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More on Plate Movements
Thick, less dense continental plate
Thin, dense oceanic plate
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Tectonic Plate movements
Look at the coastlines of South America and
Africa. I wonder of they used to fit together
Alfred Wegener
Im going to call this my Theory of Continental
Drift
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Tectonic theory

• Whats my evidence for this? Three things
• The jigsaw fit
• Each continent has similar rocks and fossils
• Each continent has similar animal species

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Tectonic theory
04/11/2013

• The Evidence
• Some continents look like they used to fit
  together
• Similar rock patterns and fossil records

The Problems Wegener couldn't explain how
continental drift happened so nobody believed him

• The Answer
• Scientists discovered 50 years later that the
  Earth generates massive amounts of heat through
  radioactive decay in the core. This heat
  generated convection currents in the mantle
  causing the crust to move
• We also now know that the sea floor is spreading
  outwards from plate boundaries

Conclusion scientists now believe Wegeners
Tectonic Theory
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Another Example of Continental Drift
The formation of mountain ranges can be explained
by tectonic theory. Consider the Himalayas at
the top of India
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Magnetic Patterns in Sea Floor Spreading
04/11/2013
The Earths magnetic field swaps poles every
million years. The above picture shows those
changes recorded over time in rocks on the sea
floor and provides evidence for long-term sea
floor spreading.
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Igneous Rock
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Volcanoes
What do you think of the following photo?
Geologists study volcanoes to get better at
forecasting future ones and to reveal more
information about the structure of the Earth.
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C2b Construction Materials
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Building Materials
Many of our common building materials are found
in the Earth
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Building Materials
Here are some common rocks used in buildings
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Limestone
Limestone is a __________ rock made up of mainly
calcium _______. Its cheap and easy to obtain.
Some facts
1) Building materials limestone can be
quarried and cut into blocks to be used in
buildings. However, it is badly affected by
____ ____.
2) Limestone ________ when heated to form
calcium oxide and carbon dioxide
3) Cement making limestone can be roasted in
a rotary kiln to produce dry cement. Its then
mixed with sand and aggregate to make _______.
Words concrete, acid rain, carbonate,
sedimentary, decomposes
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Pros and Cons of quarrying limestone
04/11/2013
Reasons why quarrying limestone is a good idea Reasons why quarrying limestone is a bad idea

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Concrete
Concrete is a strong building material and can be
made even stronger with reinforcements
Reinforcing concrete is better than plain
concrete because it is both stronger and the
steel is more flexible.
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C2c Metals and Alloys
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Extracting Metals
Some definitions
A METAL ORE is a mineral or mixture of minerals
from which it is economically viable to extract
some metal.
Most ores contain METAL OXIDES (e.g. rust iron
oxide).
To extract a metal from a metal oxide we need
to REDUCE the oxygen. This is called a REDUCTION
reaction. To put it simply
Iron ore
Reduce the oxygen to make iron
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How do we do it?
Potassium Sodium Calcium Magnesium Aluminium Carbo
n Zinc Iron Tin Lead Copper Silver Gold Platinum
Oxide
Carbon
Copper
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Reducation and Oxidation
OIL RIG Oxidation is Loss of Electrons Reduction
is Gain of Electrons
An example of reduction
An example of oxidation
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Purifying Copper
Solution containing copper ions
Oxidation
Reduction
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Recycling metals
Reasons why recycling is good
Reasons why recycling is bad
Still requires energy
Reduces demand for raw materials
Recycling
Requires money to sort and recycle
Saves energy
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Alloys
Steel is an alloy i.e. a mixture of metals.
Here are other alloys
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Alloys and their uses
Here are some common alloys and their main uses
and metals
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Smart Alloys
A smart alloy is one that can remember its
original state after being bent or stretched.
These glasses are made from a smart material
if they are bent they will return to their
original shape
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Gold alloys
Gold can be mixed with other metals to make
alloys with different properties. For example
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C2d Making Cars
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Materials in a Car
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Rusting
Task To investigate what causes rusting
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Rusting
Rusting is the adding of oxygen to iron to form
iron oxide (this is called oxidation)
No rust
No rust
Rust
Lots of rust
Salt water and acid rain can also increase the
rate of rusting.
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Iron or aluminium?
Aluminium
Does not corrode as it does not oxidise Less
dense and lighter and cars are therefore more
efficient More expensive but the car is more
efficient and lasts longer
Iron
Cheaper than aluminium Magnetic so easily
recycled Corrodes easily but also malleable
Most cars are made from steel (an alloy of
carbon) which is harder and stronger than iron
and less likely to corrode.
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Recycling
From 2015 law states that 95 of a car must be
made from recycled material. Why recycle?

1. Less space will be needed for landfill sites
2. Recycled metals only need about 1/10th of the
   energy to produce compared to producing new
   metals
3. Recycling paper reduces the amount of water and
   energy needed to produce it
4. Recycled glass only needs 80 of the energy to
   produce compared to producing new glass
5. Recycling saves on raw materials
6. Less excavation and mining costs

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C2e Manufacturing Chemicals
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Reversible Reactions
04/11/2013
Some chemical reactions are reversible. In other
words, they can go in either direction
If a reaction is EXOTHERMIC in one direction what
must it be in the opposite direction?
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Reversible Reactions
04/11/2013
When a reversible reaction occurs in a CLOSED
SYSTEM (i.e. no reactants are added or taken
away) an EQUILIBRIUM is achieved in other
words, the reaction goes at the same rate in both
directions
More products
Less products
Less products
More products
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Making Ammonia
04/11/2013
Guten Tag. My name is Fritz Haber and I won the
Nobel Prize for chemistry. I came up with the
Haber Process that uses nitrogen (from the air)
and hydrogen (from natural gas or cracking
hydrocarbons) to make ammonia
To produce ammonia from nitrogen and hydrogen you
have to use three conditions

• High pressure
• 450O C
• Iron catalyst

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Haber Process The economics
04/11/2013
A while ago we looked at reversible reactions

• 1) If temperature was DECREASED the amount of
  ammonia formed would __________...
• However, if temperature was INCREASED the rate of
  reaction in both directions would ________
  causing the ammonia to form faster
• If pressure was INCREASED the amount of ammonia
  formed would INCREASE because there are less
  molecules on the right hand side of the equation

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Haber Process Summary
04/11/2013
A low temperature increases the yield of ammonia
but is too slow A high temperature improves the
rate of reaction but decreases the yield too
much A high pressure increases the yield of
ammonia but costs a lot of money
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Industrial Processes summary
Ammonia is an important chemical as its used to
make fertilisers and nitric acid. What does the
cost of making any chemical depend on?
Cost of energy
Whether or not a catalyst can be used
What pressures and temperatures are needed
Factors affecting How much a chemical costs to
make
Cost of materials
Equipment needed
Cost of wages
How quickly the chemical can be made
How much chemical is made per day
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Chemical Economics
Hi. Were industrial scientists and we want to
make lots of chemicals and sell them to make
money. What problems would we face?

• Possible problems with making chemicals
• Reactions often produce chemicals that arent
  commercially useful or that cant be sold
• Reactions also need to be fast to be economical
  but not so fast that theyre dangerous!

Therefore we need reactions and processes that
give us a pure, high percentage yield where all
of the products are useful and the reactions
happen quickly.
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C2f Acids and Alkalis
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Universal Indicator and the pH scale
Universal Indicator is a mixture of liquids that
will produce a range of colours to show how
strong the acid or alkali is
Stomach acid
Lemon juice
Water
Soap
Oven cleaner
Baking powder
We can also use litmus paper which is red in acid
or blue in alkali.
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Acids and Alkalis
Acids produce hydrogen ions when they dissolve in
water
Alkalis produce hydroxide ions
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Neutralisation reactions
An alkali is a soluble base. When acids and
alkalis react together they will NEUTRALISE each
other
Sodium hydroxide
Hydrochloric acid
OH
Cl
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Common acids and alkalis
Acids
Alkalis
Hydrochloric acid, HCl
Sodium hydroxide, NaOH
Nitric acid, HNO3
Potassium hydroxide, KOH
Sulphuric acid, H2SO4
Magnesium hydroxide, Mg(OH)2
Calcium hydroxide, Ca(OH)2
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Making salts
Whenever an acid and alkali neutralise each other
we are left with a salt, like a chloride or a
sulphate. Complete the following table
Hydrochloric acid Sulphuric acid Nitric acid Phosphoric acid
Sodium hydroxide Sodium chloride water
Potassium hydroxide Potassium sulphate water
Calcium hydroxide Calcium nitrate water
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Adding acid to carbonates
Words dissolve, fizz, carbon dioxide, oxygen
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Reactions of metals carbonates with acid
A metal carbonate is a compound containing a
metal, carbon and oxygen.
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Reactions of metal oxides with acid
A metal oxide is a compound containing a metal
and oxide. They are sometimes called BASES. For
example
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Acids and metal hydroxides
A neutralisation reaction occurs when an acid
reacts with an alkali. An alkali is a metal
oxide or metal hydroxide dissolved in water.
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Neutralisation reactions
The basic equation for any neutralisation
reaction is
Write word and chemical equations for the
following reactions

1. Hydrochloric acid sodium hydroxide
2. Hydrochloric acid potassium hydroxide
3. Nitric acid potassium hydroxide
4. Sulphuric acid calcium hydroxide
5. Nitric acid copper oxide, CuO
6. Sulphuric acid calcium carbonate, Ca(CO)3

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C2g Fertilisers and Crop yields
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Fertilisers
The human population is growing exponentially
Because of this trend it is important to increase
food yields and fertilisers help us to do this.
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Eutrophication
One possible problem with fertilisers is
eutrophication. Eutrophication is when lakes
become stagnant due to careless use of fertiliser
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Eutrophication
Cantbreathe
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Eutrophication
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Ammonium-based Fertilisers
Guten tag. When ammonia dissolves in water it
produces an alkaline solution
This solution can be used to make fertilisers
like ammonium nitrate, ammonium phosphate and
ammonium sulfate. Very useful! I won the Nobel
Prize for Chemistry for my work in making ammonia
as my discovery has led to increased crop yields.
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Making a fertiliser
5) Evaporate some of the water and filter off
the remains to leave fertiliser crystals.
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C2h Chemicals from the sea
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Salt
Salt (sodium chloride, NaCl) is an important
chemical and is used as a preservative and as a
flavouring.
Salt can be obtained from seawater, salt deposits
or from mining
What problems could salt mining bring?
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Testing for Chlorine
Chlorine bleaches damp indicator paper
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Electrolysis of Salt Water
Salt water (e.g. seawater or brine) can be
electrolysed using an electric current to produce
chlorine and other useful products
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Half equations for this process
NaCl(aq) contains Na, OH-, Cl- and H ions
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Using Sodium Chloride in Industry
A source of sodium hydroxide
Products from it can be used to make bleach and
PVC
A source of chlorine
Industrial uses for salt
Chlorine can sterilise water
Hydrogen is used to make margarine