C1- Carbon Chemistry

• Atoms are really tiny, they have a nucleus which is positively charge and electrons that are negatively charged and these move around the nucleus in shells
• Atoms can form bonds to make molecules or compounds. Charged atoms are known as ions and if a positive ion joins with a negative ion it makes an ionic bond and a covalent bond is when they share a pair of electrons

Additives make food last longer, look and taste better

• Food colours make food look more appetising
• Flavour enhancers bring out the taste and the smell of food without adding a taste of their own
• Antioxidants help preserve food
• Emulsifiers help oil and water blend together in foods like mayonaise

Emulsions are made up of lots of droplets of one liquid suspended in another liquid. Oil and water naturally seperate into two layers with the oil floating on top of the water and emulsifiers stop them from seperating

• They have one part which is attracted to water (hydrophilic head) which bonds to water molecules
• And another part which is attracted to oil (hydrophobic tail) bonds to oil molecules
• When you shake it the oil forms droplets surrounded with the emulsifier with the hydrophilic bit facing outwards. Other oil droplets are repelled by the hydrophilic bit while the water molecules latch on so the emulsifier won't seperate out

Some foods have to be cooked

• Many foods have a better taste when they are cooked
• Some are easier to digest
• The high temperature kills microbes
• Some foods are poisonous

Causes Chemical Changes

• Eggs and Meat= are good sources of protein which change shape when you heat them, the energy from cooking them change shape when you cook them and breaks chemical bonds. The change is irreversible and it's called denaturing
• Potatoes= Each potato cell is surrounded with a rigid cell wall made of cellulose which humans can't digest. Cooking it ruptures the cell walls and it makes the starch swell and spread which makes them more soft

Baking powder undergoes thermal decomposition which is when it breaks down. These are helped by a catalyst. It is used in cakes because it creates carbon dioxide which makes the cakes rise

Chemicals that smell nice are used as perfumes and air fresheners. Esters are common in nature and flowers and fruit have natural esters. You make an ester by heating a carboxylic acid and alcohol. Acid + Alcohol -> Ester + Water

Perfumes need certain properties

• Easily Evaporates- or else the perfume won't reach your nose and you won't be able to smell it
• Non-Toxic- it must not seep through your skin and poison you
• Doesn't react with water- or else it would react with sweat
• Doesn't irritate the skin- or else you wouldn't apply it directly to your neck and wrists
• Insoluble in water- if it was soluble in water it would wash off every time you got it wet

Perfumes and Cosmetics have to be tested

• Some tests are carried out on animals which is a bit controversial but people have different opinions on this. Some think it will bring suffering to an animal and some think it is worth it so it doesn't damge humans. Because of the concerns about animal welfare it has now been banned in the EU

Solids: There are strong forces of attraction between particles which holds them in a fixed position. The particles don't move from their positions. The particles vibrate about their positions, the hotter the solid becomes the more they vibrate

Liquids: There is some force of attraction between the particles, they're free to move but tend to stick together. They don't have a definate shape and will flow and the particles are constantly moving with random motion which causes it to expand slightly when heated

Gases: There's next to no force of attraction between the particles and they are free to move, they only interact when they collide. They don't keep a definate shape or volume and they moe constantly with random notion

How we smell stuff

• When a liquid is heated the heat energy goes to the particles, and some move faster than others. Fast-moving particles at the surface will overcome the forces of attraction and escape, this is evaporation. How easily it does this is called volatility. Perfumes have to be volatile so they can evaporate enough to smell them. They have weak attractions so they can escape

• Solution: is a mixture of a solute and a solvent that doesn't seperate out
• Solute: is the substance being dissolved
• Solvent: is the liquid it's dissolving into
• Soluble: means it will dissolve
• Insoluble: means it will NOT dissolve
• Solubility: a measure of how much it will dissolve

Nail varnish is insoluble in water because the molecules of nail varnish are strongly attracted to eachother which is stronger than the attraction between the water and nail varnish molecules. The molecules of water are strongly attracted to eachother which is stronger. But nail varnish is soluble in acetone because the attraction between acetone molecules and nail varnish is stronger than the attractions holding the substances together

Pigments give paint their colour

• Paint usually contains: solvents, binding medium, pigment
• The pigment gives the paint its colour
• The biding medium is a liquid that carries the pigment bits and holds them together when it goes solid it sticks to the surface
• The solvent is the stuff that thins the paint and makes it easier to spread

Paints are colloids

• A colloid consists of really tiny particles of one kind of stuff dispersed in another kind of stuff. They are mixed in, not dissolved
• The particles can be bits of solid, droplets of liquid or bubbles of gas
• Colloids don't seperate out because the paticles are so small, they don't settle out at the bottom
• A paint is a colloid where particles of a pigment are dispersed through a liquid

Water-Based

• Emulsion paints are water based, the solvent used is water and the binding medium is acrylic or vinyl. A water based emulsion dries when the solvent evaporates leaving behind the binder and pigment as a thin solid firm. Emulsion paints are fast drying and don't produce harmful fumes

Oil Based

• The binding material is oil based and the solvent is an organic compound that'll dissolve the oil. Oil paints dry in two stages, first the solvent evaporates and then the oil is oxidised by oxygen in the air before it turns to solid
• Oil paints are very glossy, waterproof and hard-wearing but the solvents used to make them often produce harmful fumes. They're best used for painting things like outside doors and metalwork

Thermochromic Pigments

• They change colour when the become heated or cooled
• They are used in thermometers as a colour code or in baby produts and bath toys as a safety feature
• They are mixed with acrylic paints for colour ranges. Other thermochromic paints become visible when heated

Phosphorescent Pigments

• They glow in the dark by absorbing natural or artificial light and store energy in their molecules. The energy is released as light over a period of time
• This could be on watch as clock hands or emergency exit signs
• Glow in the dark watches used to be made with radioactive paints. These paints would glow for years without needing to be charged up. However they gave off atomic radiation

Polymers are formed when lots of small molecules called monomers join together. This reaction is called polymerisation and it usually needs high pressure or a catalyst.

Addition Polymers are made from Unsaturated Monomers

• The monomers that make up addition polymers have a double covalent bond
• Molecules with at least one double covalent bond between carbon atoms are called unsaturated compounds. Lots of unsaturated monomer molecules (alkenes) can open up and their double bonds and join together to form polymer chains. This is called addition polymerisation

Forces between molecules determine the properties of plastics

• Weak forces: if it is made up of long chains they are held together by weak intermolecular forces and the chains are free to slide over eachother. This means the plastic is stretchy
• Strong forces: have stronger bonds between the polymer chains these might be covalent bonds between the chains or cross-linking bridges. These plastics can't be stretched

• A single covalent bond is formed when two atoms share a pair of electrong so that both can hae a full outer shell
• Sometimes to fill up their outer shell two atoms will share two pairs of electrons

Alkenes have a C=C double bond

• Alkenes are hydrocarbons with one or more double bond. They are unsaturated compunds which means it contains a double bond.
• Their double bonds can open up and join onto things which makes alkenes much more reactive than alkanes. The first three alkenes are ETHENE, PROPENE, BUTENE.

Alkenes react with Bromine Water

• Bromine water is a bright orange solution that contains bromine. It is really reactive, if there are any double bonds they'll spring open and react with the bromine. When this happens the orange colour disappears from the solution. You can use this to test whether you have an alkene or not

 A hydrocarbon is a compound with carbon and hydrogen atoms only. They are useful and can be fuels like petrol and diesel and also plastic.

Covalent Bonds hold atoms in a molecule together

• All atoms in a hydrocarbon are held together by covalent bonds which are very strong and share electrons
• This way both atoms get a full outer shell
• Each covalent bond provides one extra electron for each atom. Each atom involved has to make enough covalent bonds to fill up its outer shell

Alkanes have a C-C single bonds

• Alkanes are the simplest hydrocarbon you can get
• Alkanes are a saturated compound which means they only contain single covalent bonds
• Alkanes won't form polymers as there are no double bonds to open up. The first 4 alkanes are methane, ethane, propane, butane

• Strong, Rigid Polymers= high density polyethen are used to make plastic milk bottles
• Light, stretchable polymers= low density polyethen are used for plastic bags and squezzy bottles
• PVC= is strong and durable s it ca be made rigid or stretchy. It can be made for window frames ad piping or synthetic leather
• Polystyrene foam= is used in packaging to protect breakable things and is used to make disposable coffee cups

Polymers are used to make clothes

• A big problem with polyurethane coating doesn't let water vapour pass through it so sweat condenses on the inside an this makes the clothing wet, uncomfortable and isn't breathable.
• Some fabrics such as GORE-TEX has a thin film of plastic called PTFE which has tiny holes which let water vapour through so it is breathable but it is waterproof and the holes aren't big enough to let big water droplets through and the PTFE repels liquid water

• Crude Oil if formed from the buried remains of plants and animals, it is a fossil fuels. Over millions of years high temperature and pressure turned it into crude oil
• Crude Oil is a mixture of lots of different hydrocarbons. The hydrocarbons are chains of carbon atoms
• The different compounds in crude oil are seperated by fractional distillation, the oil is heated until most of it has turned into gas. This enters a fractionating column and there is a temperature gradient
• The longer hydrocarbons have higher boiling points which turn it back into liquids and drain out of the column early on when they're near the bottom. The shorter hydrocarbons have lower boiling points turn to liquid and drain much later on near the top of the column
• You end up with crude oil mixture seperated out into different fractiions.

Bottom to Top

Bitumen, Oil, Diesel, Kerosene, Naptha, Petrol, LPG

Properties change as the chain gets longer

• The boiling point increases
• It gets less flammable
• It gets more viscous
• It gets less volatile

You can seperate out random mixture of all kinds of hydrocarbons into groups that have similar chain lengths and properties.

Bond in and between hydrocarbons

The strong covalent bonds between the carbons and hydrogens and the intermolecular forces of attraction are the two important bond in crude oil.

Cracking is Splitting up Long-Chain Hydrocarbons

Cracking turns long alkane molecules into smaller alkane molecules. It's a form of thermal decomposition which is when a substance is broken down into at least two new ones. For strong covalent bonds you need lots of heat and a catalyst. Alot of the longer molecules from fractional distilation are then cracked because there is more demand for things like petrol.

Conditions needed for Cracking

• Vapourised hydrocarbons are passed over powdered catalyst at about 400'c-700'c
• Aluminium oxide is the catalyst used. The long chain molecules split apart or "crack" on the surface of catalyst

CRUDE OIL PROVIDES IMPORTANT FUELS

• Crude oil provides the energy needed for electricity, heating, etc..... Oil provides the fuel for most modern transport, cars, planes and it provides raw materials for plastic.
• As the population increases more fossil fuels are burned to provide electricity.

OIL CAN CAUSE POLITICAL AND ENVIRONMENTAL PROBLEMS

• As oil gets used up the price rises and plastics and fuels get more expensive, and countries with the most will have more power over other countries. It will make it harder for countries to get hold of it
• Oil tankers can cause big oil slicks that can damage the environment. It covers birds feathers which stops them being waterproof and they die of cold. The detergents used to clean up the oil harm wildlife

THERE'S LOTS TO CONSIDER WHEN CHOOSING THE BEST FUEL

• Energy Value, Avaliability, Storage, Cost, Toxicity, Ease of Use, Pollution

COMPLETE COMBUSTION HAPPENS WHEN THERE IS PLENTY OF OXYGEN

• hydrocarbon + oxygen -> carbon dioxide + water (+energy). Many gas heaters release these gases which is okay. It releases alot of energy. CH4 + 2O2 -> 2H2O + CO2.
• The water pump draws gases from the burning hexane through the apparatus which collects inside the cool U-Tube and you can show it is water by checking the boiling point, the limewater turns milky which shows that carbon dioxide is present

INCOMPLETE COMBUSTION OF HYDROCARBONS IS NOT SAFE

• There isn't enough oxygen which gives of carbon monoxide and this is dangerous. It produces a smokey yellow flame. Hydrocarbon + Oxygen -> Carbon Dioxide + Water + Carbon Monoxide + Carbon
• Carbon Monoxide is colourless, odourless and poisonous and it's very dangerous. This can be from faulty gas fires and boilers
• 4CH4 + 6O2 -> C + 2CO + CO2 + 8H2O

PHASE 1- VOLCANOES GAVE OUT STEAM AND CARBON DIOXIDE

• When the Earth's surface cooled and a thin crust was formed but volcanoes erupted. Water vapour was formed and condensed to form oceans

PHASE 2- GREEN PLANTS EVOLVED AND PRODUCED OXYGEN

• Alot of carbon dioxide dissolved into the oceans and green plants evolved and this increased the amount of oxygen, nitrogen gas was put into the air

PHASE 3- OZONE LAYER ALLOWS EVOLUTION OF COMPLEX ANIMALS

• The build up of oxygen killed off early organisms but it allowed the development of more complex organisms. The oxygen also created the ozone layer which blocked harmful rays from the sun and enabled complex organisms to evolve
• The present composition of the atmosphere: 78% Nitrogen, 21% Oxygen, 0.035% Carbon Dioxide

SULPHUR DIOXIDE

• When fossil fuels are burned they release carbon dioxide, sulphur dioxide and nitrogen oxide. When these gases mix in the clouds they form sulfuric acid and nitric acid which falls as acid rain.
• This causes lakes to become acidic which kills fish, and it kills trees and damages limestone buildings. Photochemical smog is a type of air pollution which produces ozone and can cause breathing difficulties, headaches and tiredness

CARBON MONOXIDE IS A POISONOUS GAS

• It can stop blood from carrying oxygen around the body and can cause fainting, a coma and death. Catalytic converters reduce the amount of carbon monxide and the catalyst is normally a mixture of platinum and rhodium.