1. Cooking Why do we cook food? When food is cooked...
High temperature kills harmful bacteria
Texture of food is improved
Flavour of food is enhanced
Food is easier for the body to digest
When food is cooked...
It cannot return to its raw state
The change is irreversible
An energy change takes place in the food

2. Cooking
Proteins
Cooking is chemical change because a new substance is made
Meat and eggs are good sources of proteins Proteins are large molecules that have definite shapes
A protein is a long molecule that has four types of structure -
Primary- This is the sequence of amino acids in a protein chain
Secondary-
This is when a protein coils into a helix shape
Tertiary-
This is when a protein has a folding structure as new bonds are formed.
Quaternary-
This is when more than one protein joins to form a large protein such as haemoglobin

3. Cooking
Baking powder
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

4. Cooking Testing for carbon dioxide Potatoes
Limewater turns from colourless to milky white if carbon dioxide is present.
Potatoes
When a potato is cooked its cell walls breakdown and starch grains burst.
This makes the potato easier for the body to digest.

5. Food Additives
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

7. -Soiling happens when a food reacts with oxygen, bacteria or mould.
-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

8. Intelligent Packaging
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

9. 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. 9

10. Why do perfumes need certain qualities?
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 10

11. 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. 11

12. Attraction between particles
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. 12

13. Chemistry Revision Crude oils...

14. 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 hydro-carbons =] )

15. 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!!

16. 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

17. C1e- Making Polymers

18. C----------C----------C----------C
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

19. 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.

20. 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

21. C1F Designer polymers 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)
Plastic bags
Poly(styrene)
Insulates
Absorbs shock
Packaging
Poly(propylene)
strong
ropes

22. More on breathable polymers
GORE-TEX is a material that is waterproof and flexible but it is also breathable unlike PVC
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.
Nylon
GORE-TEX
waterproof
flexible
Non-breathable
breathable
More on breathable polymers
wind
Water vapour from sweat is small enough to pass through
Water droplets don’t pass through the membrane as they are too big
Wind cannot pass through as it gets lost in the membrane
The inner layer of the clothing is made with PTFE (polytetrafluoroethene)

23. Biodegradable polymers
Polymers can
be disposed:
In landfill sites
- by burning
By recycling
Problems of non-biodegradable polymers are:
Difficult to dispose of
Cause litter
Use
Polymer
Other Material
Contact lens
Wet on the eye
Dry on the eye
Teeth filling
Attractive
Looks metallic
Wound dressing
waterproof
Gets wet
Biodegradable polymers
Scientists are developing addition polymers that are biodegradable. They are easily disposed of.
Problems of non-biodegradable polymers
Disposal by burning or landfill sites wastes valuable resources
Hard to sort different polymers so it is hard to recycle.
Landfill sites get filled quickly and waste valuable land
Burning waste produces toxic gas

24. 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.
Intermolecular forces of attraction are week
monomer
Intramolecular bonds are strong
Week forces of
attraction
Pulling force
Polymer stretches
Pulling force
Rigid polymer
Strong bonds

25. Using Carbon Fuels

26. Comparing Fuels
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.

27. Different fuels are chosen for different jobs.
Characteristic
Coal
Petrol
Energy value
High
Availability
Good
Storage
Bulky and dirty
Volatile
Cost
Toxicity
Produces acid fumes
Produces less acid fumes
Pollution caused
Acid rain, carbon dioxide, soot
Carbon dioxide, nitrous oxides
Ease of use
Easier to store as an energy source for power stations
Flows easily around an engine so makes a good energy source for a car.

28. Combustion
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.

29. More on complete combustion
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.

30. 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.

31. You can calculate the energy transferred using this formula:
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:
You can calculate the energy output of a fuel using this formula:
Energy transferred = mass of water x 4.2 x temp change
Energy per gram = energy supplied/mass of fuel burnt