• 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

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

• 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 -Food additives are added to preserve food so that it can be distribute around the country or go to it can be distribute around the country or go to

other countries without other countries without spoiling spoiling

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

-Additives are also added to give a different -Additives are also added to give a different sensory experience. They are also used to sensory experience. They are also used to

enhance the colour or flavour of foodenhance the colour or flavour of food

Intelligent packaging is another Intelligent packaging is another method used to stop food method used to stop food

spoilingspoiling Active packaging: Actively Active packaging: Actively

changes the condition of changes the condition of packaged food to extend its packaged food to extend its

life while maintaining the life while maintaining the quality of the productsquality of the products

Intelligent packaging: Intelligent packaging: Monitors the condition of Monitors the condition of packaged food and gives packaged food and gives

information on the quality of information on the quality of the packaged food using the packaged food using sensors and indicatorssensors and indicators

CI REVISION

What makes a good perfume?

A good perfume:Evaporates easily

Is non ToxicDoes not react with waterDoes 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 peopleNo water reaction: perfume wont react with perspiration.Does not irritate skin: so perfume can be sprayed onto skinInsoluble 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

SolubilitySolubility

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.

SolutionsA 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.

DiffusionDiffusion

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 Chemistry Revision Crude oils... Crude oils...

What is crude oil ?What is crude oil ?

Crude oil is formed from the buried remains of Crude oil is formed from the buried remains of plants and animals- it is a fossil fuel.(Millions plants and animals- it is a fossil fuel.(Millions of years of pressure and high temperature of years of pressure and high temperature causes the remains to turn to crude oil which causes the remains to turn to crude oil which can be drilled up and parts of it used for can be drilled up and parts of it used for medicne fuels and lots of other things!)medicne fuels and lots of other things!)

(the complicated ways of saying this... Crude oil (the complicated ways of saying this... Crude oil is an occuring flammable liquid found in rock is an occuring flammable liquid found in rock formations, in the eart made of a mixture of formations, in the eart made of a mixture of hydro-carbons =] )hydro-carbons =] )

Fractional DistillationFractional Distillation

The low down- Separating parts in a mixture.The low down- Separating parts in a mixture. Crude oil is a mixture of hydrocarbons of different Crude oil is a mixture of hydrocarbons of different

sized molecules , hydrcarbons are basically fuels sized molecules , hydrcarbons are basically fuels such as petrol and diesel, they are made of just such as petrol and diesel, they are made of just carbon and hydrogen, the bigger and longer the carbon and hydrogen, the bigger and longer the molecules, the less runny the hydro carbon...And the molecules, the less runny the hydro carbon...And the stronger the intermoleculer forces between the stronger the intermoleculer forces between the molecules, so alot of energy is needed to seperate molecules, so alot of energy is needed to seperate the molecules so the boiling point is higher.the molecules so the boiling point is higher.

So fractional distilation splits up crude oil into So fractional distilation splits up crude oil into seperate fractions. seperate fractions.

The shorter the molecules the lower the The shorter the molecules the lower the themperatuere it condenses!!themperatuere it condenses!!

Cracking Cracking Cracking is splitting up long chained Cracking is splitting up long chained

hydrocarbons.hydrocarbons.Cracking is a process that turns the long chain Cracking is a process that turns the long chain

hydrocarbons into shorter molecules which hydrocarbons into shorter molecules which are more useful.are more useful.

Cracking is a form of thermal decompostition, Cracking is a form of thermal decompostition, which means just breacking down molecules which means just breacking down molecules into simpler molecules by heating them into simpler molecules by heating them

A lot of longer molecules produced from f.d are A lot of longer molecules produced from f.d are cracked into smaller ones because thes cracked into smaller ones because thes moree in demand like petrol and parrifin.moree in demand like petrol and parrifin.

Cracking also produces alkanes which are Cracking also produces alkanes which are needed to make plastics.needed to make plastics.

A catalyst is used to speed up reaction and A catalyst is used to speed up reaction and make it happenmake it happen

C1e- Making PolymersC1e- Making Polymers

PolymersPolymersPlastic is a polymer. We use plastic as a material in are Plastic is a polymer. We use plastic as a material in are everyday lives. A polymer is a big molecule which is made everyday lives. A polymer is a big molecule which is made up of monomers. There are lots of different polymers such up of monomers. There are lots of different polymers such as: ethene, styrene, methene and propene.as: ethene, styrene, methene and propene.

PolymerisationPolymerisation when lots of monomers are connected to make a polymer the when lots of monomers are connected to make a polymer the

reaction is called polymerisation. If all of the monomers are reaction is called polymerisation. If all of the monomers are the same then it is called additional polymerisation and loads the same then it is called additional polymerisation and loads of them are joined. For polymerisation there has to be high of them are joined. For polymerisation there has to be high pressure and a catalyst for it to work best. This will cause the pressure and a catalyst for it to work best. This will cause the double bond joining the two to break. Each of the separate double bond joining the two to break. Each of the separate atoms will then need to rejoin with another molecule with atoms will then need to rejoin with another molecule with needs to join with another and so on. needs to join with another and so on.

H H H HI I I I

C----------C----------C----------CI I I IH H H H

HydrocarbonsHydrocarbonsHydrocarbons 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.

PolymersPolymers 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.

SaturationBromine 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 AlkanesAlkenes and Alkanes Hydrocarbons are compounds made from alkenes Hydrocarbons are compounds made from alkenes

(which are unsaturated) and alkanes (which are (which are unsaturated) and alkanes (which are saturated). Alkenes can act as a monomer under saturated). Alkenes can act as a monomer under heat, pressure and with use of a catalyst. The formula heat, pressure and with use of a catalyst. The formula of a alkene is ‘CnH2n’ and the formula for an alkane of a alkene is ‘CnH2n’ and the formula for an alkane is ‘CnH2n+2’. If a Hydrocarbon ends in ‘ene’ then it is is ‘CnH2n+2’. If a Hydrocarbon ends in ‘ene’ then it is an alkene, if it ends with ‘ane’ then it is an alkane.an alkene, if it ends with ‘ane’ then it is an alkane.

Here are some useful hydrocarbons:Here are some useful hydrocarbons:• Methane/-Methane/-• Ethane/EtheneEthane/Ethene• Propene/PropanePropene/Propane• Butane/ButeneButane/Butene

C1FC1F Designer polymers Designer polymers

Uses of polymers

•Different things are made of different polymers.

•Each polymer is chosen for its job. For example PVC poly(vinylchloride)

PolymerPolymer Property 1Property 1 Property 2Property 2 UseUse

PVC PVC poly(vinylchloride)poly(vinylchloride)

WaterproofWaterproof FlexibleFlexible RaincoatsRaincoats

Poly(ethene)Poly(ethene) WaterproofWaterproof FlexibleFlexible Plastic bagsPlastic bags

Poly(styrene)Poly(styrene) InsulatesInsulates Absorbs Absorbs shockshock

PackagingPackaging

Poly(propylene)Poly(propylene) strongstrong FlexibleFlexible ropesropes

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

The inner layer of the clothing is made with PTFE (polytetrafluoroethene)

wind

Water droplets don’t pass through the

membrane as they are too big

Water vapour from sweat is small enough

to pass through

Wind cannot pass through as it gets lost in

the membrane

Polymers

Use Polymer Other Material

Contact lens Wet on the eye Dry on the eye

Teeth filling Attractive Looks metallic

Wound dressing waterproof Gets wet

Polymers can

be disposed:

-In landfill sites

- by burning

-By recycling

Problems of non-biodegradable polymers are:

-Difficult to dispose of

-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

monomer

Intramolecular bonds are strong

Intermolecular forces of

attraction are week

Pulling force

Pulling force

Polymer stretchesWeek forces of

attraction

Strong bonds

Rigid polymer

Atoms of the monomers are held together by Intramolecular bonds

Two chains of a polymer are held

together by intermolecular forces.

They are week.

Using Carbon FuelsUsing Carbon Fuels

Comparing FuelsComparing Fuels A fuel is chosen because of its characteristics. Energy value, A fuel is chosen because of its characteristics. Energy value,

availability, ease of use, storage method, cost, toxcity, pollution availability, ease of use, storage method, cost, toxcity, pollution caused.caused.

Burning hydrocarbon fuels produces energy, fuel + oxygen Burning hydrocarbon fuels produces energy, fuel + oxygen carbon dioxide + water.carbon dioxide + water.

Fuel burns in oxygen to give carbon dioxide and water. Limewater is 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 carbon dioxide. White copper sulphate powder is used to test for water, which is produced as steam.used to test for water, which is produced as steam.

Characteristic Characteristic CoalCoal PetrolPetrol

Energy valueEnergy value HighHigh HighHigh

Availability Availability GoodGood GoodGood

StorageStorage Bulky and dirty Bulky and dirty VolatileVolatile

CostCost HighHigh HighHigh

ToxicityToxicity Produces acid fumesProduces acid fumes Produces less acid Produces less acid fumesfumes

Pollution causedPollution caused Acid rain, carbon Acid rain, carbon dioxide, sootdioxide, soot

Carbon dioxide, Carbon dioxide, nitrous oxidesnitrous oxides

Ease of useEase of use Easier to store as an Easier to store as an energy source for energy source for power stationspower stations

Flows easily around Flows easily around an engine so makes an engine so makes a good energy a good energy source for a car.source for a car.

Different fuels are chosen for different jobs.

CombustionCombustion Complete combustion occurs when a fuel burns completely in air, a Complete combustion occurs when a fuel burns completely in air, a

fuel such as methane uses oxygen in the air to produce products. fuel such as methane uses oxygen in the air to produce products. Methane + oxygen = carbon dioxide + water. In complete Methane + oxygen = carbon dioxide + water. In complete combustion more energy is released than in incomplete combustion.combustion more energy is released than in incomplete combustion.

Incomplete combustion occurs when a fuel burns in limited oxygen. Incomplete combustion occurs when a fuel burns in limited oxygen. The products are carbon monoxide and water. Complete The products are carbon monoxide and water. Complete combustion is better because; less soot is made, more heat is combustion is better because; less soot is made, more heat is released, toxic carbon monoxide gas isn’t produced.released, toxic carbon monoxide gas isn’t produced.

More on complete combustionMore on complete combustion

Methane is a common used hydrocarbon fuel. The formula for Methane is a common used hydrocarbon fuel. The formula for methane is CH4.methane is CH4.

Complete combustion can be shown by the equation, CH4 + 2O2 = Complete combustion can be shown by the equation, CH4 + 2O2 = CO2 + 2H2O.CO2 + 2H2O.

EnergyEnergy

Exothermic reactionsExothermic reactions When energy is transferred out into the When energy is transferred out into the

surrounding area it is surrounding area it is exoexothermic. Exothermic thermic. Exothermic reactions cause a temperature increase as they reactions cause a temperature increase as they are taking in more energy. exothermic makes are taking in more energy. exothermic makes bondsbonds

When energy is taken in form the surrounding When energy is taken in form the surrounding area it is area it is endoendothermic. Endothermic reactions thermic. Endothermic reactions cause a temperature decrease. Because it is cause a temperature decrease. Because it is losing energy. Endothermic reactions are bond losing energy. Endothermic reactions are bond making reactions.making reactions.

Something burning with a blue flame has plenty of Something burning with a blue flame has plenty of oxygen, and something burning with a yellow flame has oxygen, and something burning with a yellow flame has little oxygen. This is called incomplete combustion. little oxygen. This is called incomplete combustion.

You can find the mass of fuel burnt by taking the mass You can find the mass of fuel burnt by taking the mass after burning away from the mass before burning.after burning away from the mass before burning.

You can calculate the energy transferred using this You can calculate the energy transferred using this formula:formula:

You can calculate the energy output of a fuel using this You can calculate the energy output of a fuel using this formulaformula::

Energy per gram = energy supplied/mass of fuel burnt

Energy transferred = mass of water x 4.2 x temp change