Transcript C1 Revision

• High temperature kills harmful bacteria
• Texture of food is improved
• Flavour of food is enhanced
• Food is easier for the body to digest
• It cannot return to its raw state
• The change is irreversible
• An energy change takes place in the food
Meat and eggs are good sources of
proteins
Proteins are large
molecules that have definite shapes
Cooking is chemical
change because a
new substance is
made
A protein is a long molecule that has four types of structure Primary- This
is the sequence of
amino acids in
a protein chain
TertiaryThis is when a protein
has a folding
structure as new
bonds are formed.
SecondaryThis is when a
protein coils into
a helix shape
QuaternaryThis is when more than
one protein joins to form
a large protein such
as haemoglobin
• Baking
powder is a chemical called sodium hydrogen carbonate
• When heated it decomposes to give sodium carbonate, carbon
dioxide and water.
Sodium hydrogen carbonate
Sodium carbonate +
Carbon dioxide + water
2NaHCO3
Na2CO3 + H2O + CO2
Limewater turns
from colourless
to milky white if
carbon dioxide is
present.
When a potato is cooked its cell walls
breakdown and starch grains burst.
This makes the potato easier for the
body to digest.
The Four Main Types Of Food Additives Are:
•Antioxidants
•Colours
•Emulsifiers
•Flavour Enhancers
Antioxidants stop food from reacting with oxygen and turning bad
An antioxidant is used to prevent apples from turning brown. It is also called ascorbic acid (vitamin c)
Every additive has its own reference number vitamin c-E300
-Food additives are added to preserve food so that it can be distribute around the
country or go to other countries without spoiling
-Soiling happens when a food reacts with oxygen, bacteria or mould.
-Additives are also added to give a different sensory experience. They are also used
to enhance the colour or flavour of food
Intelligent packaging is another method used to
stop food spoiling
 Active packaging: Actively changes the
condition of packaged food to extend its
life while maintaining the quality of the
products
 Intelligent packaging: Monitors the
condition of packaged food and gives
information on the quality of the packaged
food using sensors and indicators
CI REVISION
What makes a good perfume?
A good perfume:
Evaporates easily
Is non Toxic
Does not react with water
Does not irritate the skin
Is insoluble in water
Perfumes can be made using natural
substances or can be made synthetically.
Making a Perfume
To make a perfume, a chemical called an ester is made. An alcohol
mixed with an acid makes an ester.
Ethanol+ethanoic acid+Ethyl ethanoate
Why do perfumes need certain qualities?
Evaporates Easily: perfume particles reach nose.
Non Toxic: Will not poison people
No water reaction: perfume wont react with perspiration.
Does not irritate skin: so perfume can be sprayed onto skin
Insoluble in water: perfume is not washed off skin
Volatile perfumes are liquids that have energetic fast moving particles at room
temperature, there is only a weak attraction between particles, so forces of
attraction between molecules are easily overcome
Solubility
A substance that dissolves in water is soluble. The substance is called the solute and
the liquid that it dissolves in is called the solvent. A substance that does not dissolve in
liquid is called insoluble.
Solutions
A solution is a solute and a solvent that do not separate. Esters can be used as
solvents and solvents can be used as cleaners.
Cosmetics must not cause rashes or itchiness, or cause skin damage or other life
threateing illnesses, i.e cancer.
Some people say testing on animals is bad as the animals may be harmed, or
there are other effective ways of testing things.
Some people say that testing on animals is ok because, they think the animals
reaction would closely mimic the humans or it makes them feel safer.
Diffusion
Diffusion is the movement of particles from an area of high concentration to an area of low
concentration.
Evaporation
Liquid particles are weakly attracted to each other. When some particles increase their
kinetic energy, the weak forces are overcome and particles escape.
Attraction between particles
Water does not dissolve nail varnish because the force of attraction between two
water molecules is stronger than that between a water and a nail varnish molecules.
Also the force of attraction between two varnish molecules is stronger than between a
varnish molecule and a water molecule.
Chemistry Revision
Crude oils...
What is crude oil ?
Crude oil is formed from the buried remains of
plants and animals- it is a fossil fuel.(Millions of
years of pressure and high temperature causes
the remains to turn to crude oil which can be
drilled up and parts of it used for medicne fuels
and lots of other things!)
(the complicated ways of saying this... Crude oil is an
occuring flammable liquid found in rock
formations, in the eart made of a mixture of hydrocarbons =] )
Fractional Distillation
The low down- Separating parts in a mixture.
Crude oil is a mixture of hydrocarbons of different
sized molecules , hydrcarbons are basically fuels
such as petrol and diesel, they are made of just
carbon and hydrogen, the bigger and longer the
molecules, the less runny the hydro carbon...And
the stronger the intermoleculer forces between the
molecules, so alot of energy is needed to seperate
the molecules so the boiling point is higher.
So fractional distilation splits up crude oil into
seperate fractions.
The shorter the molecules the lower the
themperatuere it condenses!!
Cracking
Cracking is splitting up long chained hydrocarbons.
Cracking is a process that turns the long chain
hydrocarbons into shorter molecules which are
more useful.
Cracking is a form of thermal decompostition,
which means just breacking down molecules into
simpler molecules by heating them
A lot of longer molecules produced from f.d are
cracked into smaller ones because thes moree in
demand like petrol and parrifin.
Cracking also produces alkanes which are needed to
make plastics.
A catalyst is used to speed up reaction and make it
happen
C1e- Making Polymers
Polymers
Plastic is a polymer. We use plastic as a material in are everyday lives.
A polymer is a big molecule which is made up of monomers. There
are lots of different polymers such as: ethene, styrene, methene and
propene.
Polymerisation
when lots of monomers are connected to make a polymer the
reaction is called polymerisation. If all of the monomers are the same
then it is called additional polymerisation and loads of them are
joined. For polymerisation there has to be high pressure and a
catalyst for it to work best. This will cause the double bond joining
the two to break. Each of the separate atoms will then need to rejoin
with another molecule with needs to join with another and so on.
H
H
H
H
I
I
I
I
C----------C----------C----------C
I
I
I
I
H
H
H
H
Hydrocarbons
Hydrocarbons are made from hydrogen and carbon. If it contains an
additional atom then it is not a hydrocarbon. A Hydrocarbon
is named according to the number of bonds and the number of
carbon atoms.
Polymers
Polymers are made from hydrocarbons which have a double bond
between two carbon atoms. They are either alkenes or alkanes
depending on whether it is saturated or not.
Saturation
Bromine solution is orange and is used to test for unsaturation. If
an alkene is present it will turn clear because of the reaction that
takes place with the alkene to produce a new compound. If it is an
Alkane then it does not react therefore stays orange.
Alkenes and Alkanes
Hydrocarbons are compounds made from alkenes (which
are unsaturated) and alkanes (which are saturated).
Alkenes can act as a monomer under heat, pressure and
with use of a catalyst. The formula of a alkene is ‘CnH2n’
and the formula for an alkane is ‘CnH2n+2’. If a
Hydrocarbon ends in ‘ene’ then it is an alkene, if it ends
with ‘ane’ then it is an alkane.
Here are some useful hydrocarbons:
• Methane/• Ethane/Ethene
• Propene/Propane
• Butane/Butene
Designer polymers
C1F
Uses of polymers
•Different things are made of
different polymers.
•Each polymer is chosen for its
job. For example PVC
poly(vinylchloride)
Polymer
Property 1
Property 2
Use
PVC
poly(vinylchloride)
Waterproof
Flexible
Raincoats
Poly(ethene)
Waterproof
Flexible
Plastic bags
Poly(styrene)
Insulates
Absorbs
shock
Packaging
Poly(propylene)
strong
Flexible
ropes
Breathable polymers
•Nylon is used to make coats as
it is tough, light weight and
waterproof. The problem is that
it doesn’t let water vapour out.
•GORE-TEX is a material that is
waterproof and flexible but it is
also breathable unlike PVC
Nylon
GORE-TEX
waterproof
waterproof
flexible
flexible
Non-breathable
breathable
More on breathable polymers
wind
Wind cannot pass
through as it gets lost in
the membrane
Water vapour from
sweat is small enough
to pass through
Water droplets don’t
pass through the
membrane as they are
too big
The inner layer of the clothing is made with PTFE (polytetrafluoroethene)
Polymers
Polymers can
Problems of nonbiodegradable
polymers are:
Use
Polymer
Other Material
be disposed:
Contact lens
Wet on the eye
Dry on the eye
-In landfill sites
Teeth filling
Attractive
Looks metallic
- by burning
-Difficult to
dispose of
Wound dressing
waterproof
Gets wet
-By recycling
-Cause litter
Biodegradable polymers
Scientists are developing addition polymers that are biodegradable. They are easily
disposed of.
Problems of non-biodegradable polymers
•Landfill sites get filled
quickly and waste
valuable land
•Burning waste
produces toxic gas
•Disposal by burning
or landfill sites wastes
valuable resources
•Hard to sort different
polymers so it is hard
to recycle.
Stretchy polymers and rigid polymers
Atoms of the monomers
are held together by
Intramolecular bonds
Two chains of a polymer
are held together by
intermolecular forces.
They are week.
Week forces of
monomer
Intramolecular
bonds are strong
Pulling
force
Polymer stretches
attraction
Strong
bonds
Pulling
force
Intermolecular
forces of
attraction are
week
Rigid
polymer
Using Carbon Fuels
Comparing Fuels
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A fuel is chosen because of its characteristics. Energy value,
availability, ease of use, storage method, cost, toxcity, pollution
caused.
Burning hydrocarbon fuels produces energy, fuel + oxygen
carbon dioxide + water.
Fuel burns in oxygen to give carbon dioxide and water. Limewater is
used to test for carbon dioxide. White copper sulphate powder is
used to test for water, which is produced as steam.
Different fuels are chosen for different jobs.
Characteristic
Coal
Petrol
Energy value
High
High
Availability
Good
Good
Storage
Bulky and dirty
Volatile
Cost
High
High
Toxicity
Produces acid fumes Produces less acid
fumes
Pollution caused
Acid rain, carbon
dioxide, soot
Ease of use
Easier to store as an Flows easily around
energy source for
an engine so makes
power stations
a good energy
source for a car.
Carbon dioxide,
nitrous oxides
Combustion
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Complete combustion occurs when a fuel burns completely in air, a
fuel such as methane uses oxygen in the air to produce products.
Methane + oxygen = carbon dioxide + water. In complete
combustion more energy is released than in incomplete combustion.
Incomplete combustion occurs when a fuel burns in limited oxygen.
The products are carbon monoxide and water. Complete combustion
is better because; less soot is made, more heat is released, toxic
carbon monoxide gas isn’t produced.
More on complete combustion
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Methane is a common used hydrocarbon fuel. The formula for
methane is CH4.
Complete combustion can be shown by the equation, CH4 + 2O2 =
CO2 + 2H2O.
Energy
Exothermic reactions
 When energy is transferred out into the
surrounding area it is exothermic. Exothermic
reactions cause a temperature increase as they
are taking in more energy. exothermic makes
bonds
 When energy is taken in form the surrounding
area it is endothermic. Endothermic reactions
cause a temperature decrease. Because it is
losing energy. Endothermic reactions are bond
making reactions.
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Something burning with a blue flame has plenty of
oxygen, and something burning with a yellow flame has
little oxygen. This is called incomplete combustion.
You can find the mass of fuel burnt by taking the mass
after burning away from the mass before burning.
You can calculate the energy transferred using this
formula:
Energy transferred = mass of water x 4.2 x temp change

You can calculate the energy output of a fuel using this
formula:
Energy per gram = energy supplied/mass of fuel burnt