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Combustion (burning) reaction
Some chemicals can react rapidly with
oxygen to release energy and possible
light.
Incomplete combustion
• If there isn’t enough oxygen to
the burn the fuel completely,
incomplete combustion takes
place.
• Carbon monoxide is formed.
• It also releases small particles of
carbon into the air.
What influences Air
Quality?
1. Emissions
Vehicles release
pollutants into the air.
2. Weather
Winds mix up and
transport pollutants.
Name
Health Effects
Sulfur Dioxide
Acid rain
Carbon Monoxide
A poisonous gas. It reacts with
blood and can kill you.
Nitrogen Dioxide
Acid rain.
Causes breathing problems.
Can make asthma worse.
Particulates
(tiny bits of solid
carbon suspended
in the air)
Make things dirty.
Breathed into your lungs.
Can make asthma worse.
Can make lung infections
worse.
Air
Combustion
Pollutants
C1
Carbon reacting with oxygen to form carbon monoxide
• The Earth’s atmosphere provides a
protective blanket that supports life.
Earth’s
Atmosphere
Atoms
•Human activities have altered the balance of
these chemicals as it can be damaged easily.
•The concentration of C02 doubled since the
burning of fossil fuels.
A primary pollutant is an air pollutant
emitted directly from a source.
A secondary pollutant is not directly
emitted, but forms when other pollutants
(primary) react in the atmosphere.
Example: N0 joins with oxygen atoms in
the air to form N02.
Hydrogen reacting with oxygen
to form water
Nitrogen reacting with oxygen to
form Nitrogen monoxide
Car engines use catalytic converters to
reduce the amount of pollution released.
How it works:
• Molecules of polluting gases are pumped
from the engine past the catalyst.
• The catalyst splits up the molecules into
their atoms.
• The atoms then recombine into molecules
of relatively harmless substances such as
carbon dioxide, nitrogen, and water, which
blow out safely through the exhaust.
Conservation of atoms
Reactants → Products
•The products have different properties
from the reactants.
•As a chemical reaction takes place, atoms in
the reactants are rearranged to make the
products.
•No atoms are added or taken away.
What are Polymers?
•A polymer is a long-chained molecule that is
composed of individual units of ethene, called
monomers.
•Materials can be obtained or made from living
things and chemicals. These are known as natural
and synthetic materials.
The shape and
size of the longchain molecules
in a fibre make
the material what
it is and gives it
it’s special
properties.
Polymer with no cross-links
Modifying polymers
Different polymers have different properties,
depending on the small molecules they were
made from; but the properties of a polymer
can also be changed.
Polymer chains
•Many polymers, such as polythene,
contain long molecules that lie side by side.
These can uncoil and slide past each other,
making the material flexible.
Molecular
Structure
Polymers
Ethene makes polythene
By polymerising other small molecules, a wide
variety of different polymers can be made.
These synthetic materials have many uses.
Getting the right material
•The products that we use are made of different
materials. Choosing the right material for each
job depends on the properties of that material.
C2
Material
Properties
•Manufacturers and designers have to choose the
right materials to make their products. They
decide which materials to use based on their
properties and cost.
Solid materials can differ in the following ways:
• Melting point
• Strength in tension (when pulled)
• Strength in compression (when pushed)
• Stiffness
• Hardness
• Density
Life Cycle
Assessment
•Long polymer chains have stronger forces
of attraction than shorter ones. By making
the chains of a polymer longer, a stronger
and less flexible material is produced.
A Life Cycle Assessment, or LCA, is a study
of the stages in the life of a manufactured
product. It can be used to assess the
environmental impact of the manufacture
and use of different materials and
products.
The raw materials for making the
product
The energy used to manufacture it
CRADLE
The energy needed to use it
The energy needed to maintain it
The chemicals needed to maintain it
USE
Nylon is used
to make
tights due to
its flexibility.
The raw materials for making the
product
The energy used to manufacture it
GRAVE
Polymer with cross-links
What is Vulcanisation?
•Natural rubber is sticky, deforms easily when warm,
and is brittle when cold. In this state it cannot be
used to make products with a good level of elasticity.
•Vulcanisation is the process in which rubber is
heated at high temperatures with sulphur.
•The sulphur forms chemical bonds, or cross-links,
which link together the chains of individual polymers.
•These cross-links lock the material in a regular
shape and make the material tougher and less
flexible, increasing its worth and uses.
Various amounts of crystallinity
•By carefully controlling the amount of
branching, it is possible to make polymers
with various amounts of crystallinity.
•This means it is possible to make a polymer
with the exact properties that are required
for a particular purpose.
•Plasticizer molecules behave like ‘molecular lubricants.’
•They push the polymer molecules slightly further apart.
•This weakens the intermolecular forces between them
and allows the polymers chains to slide over each other
more easily, making the material softer and more
flexible.
•Unplasticized PVC, usually called uPVC, is hard.
•Plasticised PVC is soft.
Sulphur
PVC and
uPVC
Vulcanisation
PVC
Molecules
C3
HDPE
No side
branches
Has side
branches
High-Density Polythene (HDPE)
The polymer molecules line up regularly to give a
crystalline structure.
This means that:
•The material has a higher density than LDPE.
•The forces of attraction between polymer molecules
are strong.
•The material is stronger and has a higher melting point
than LDPE.
Plasticizers
LDPE
Side Branches
•When polythene molecules made from
ethene are exposed to pressure, side
branches are given off.
• The polymers will still grow but from
multiple branches and will not line up neatly.
•LDPE in an example of this.
Low-Density Polythene (LDPE)
The side branches stop the polymer molecules from
lining up regularly. Its structure is not crystalline.
This means that:
•The material has a lower density than HDPE.
•The forces of attraction between polymer molecules
are weakened.
•The material is less strong and has a lower melting
point than HDPE.
Food Additives
•Colourings: Replace or add [natural] colours.
•Flavourings: Gives the food a certain taste
•Sweeteners: Increase sweetness and replaces
sugar in products using artificial sweeteners
such as aspartame.
•Emulsifiers: Help to mix together substances
which do not easily mix, such as oil and water.
•Stabilisers: Stops these substances separating
again after they have been mixed.
•Preservatives: Prevents growth of microbes
such as bacteria in foods during storage to
increase shelf life.
•Antioxidants: Prevents reaction of chemicals in
food with oxygen in the air.
E Numbers
A food additive that has passed
safety tests to allow its legal use in
the EU is given an E number.
•E100 series: Colours
•E200 series: Preservatives
•E300 series: Antioxidants
•E400+ series: Emulsifiers, stabilisers
and other additives
•Diabetes is a condition where the amount of
glucose in your blood is too high because the
body cannot use it properly.
•Insulin is the hormone produced by the
pancreas that allows glucose to enter the body’s
cells, where it is used as fuel for energy.
•Glucose comes from digesting carbohydrate
and is also produced by the liver.
Type 1 Diabetes
Type 2 Diabetes
Who it
affects
Children and
teenagers;
adults under the
age of 40
Adults, or over
40’s; greater risk of
those who have
poor diets and/or
are overweight
How it
works
The pancreas
stops making
enough insulin
The body no longer
responds to its
insulin
How it is
controlled
Injections of
insulin for life
and a healthy
diet
Exercise and
appropriate diet
Preserving
and
Processing
Food
Natural
Polymers
C3
Diabetes
Carbohydrates and proteins
•Many of the chemicals in living things are natural polymers.
•Animals and plants need natural polymers like proteins and
carbohydrates.
•Food contains natural polymers which are broken down
during digestion into soluble compounds.
•These are absorbed into the blood and transported around
the body.
•The breakdown products are then used by the body to
make new polymers, during a process called Synthesis.
Protein
Amino Acid
Molecule
Carbohydrate
Sugar Molecule
Plants make their own food through
photosynthesis. They require hydrogen,
carbon, oxygen, NPK and water for growth.
Farming
•High Blood Glucose Level
Pancreas produces insulin which
enters the blood. Insulin allows
the glucose to be absorbed by
body cells, reducing blood glucose.
•Low Blood Glucose Level
Pancreas stops producing insulin.
This results in less glucose being
absorbed by the body cells and
more to accumulate in your blood.
•Intensive farming involves using loads of
artificial fertilisers, herbicides and pesticides
and means growing just one crop year after
year.
•Organic farming aims to produce crops
without using artificial fertilisers.
Natural Cycle of Nutrients
•As plants grow they remove NPK from the soil and it
becomes less fertile.
•Farmers need to be able to replace elements that are
removed by plants and stop weeds, pests and disease.
•These elements are returned to the soil when living
organisms die and decay, or when animals eat other living
things.
•These processes means that there is a continuous cycling
of elements.