- Crude oil is a non-renewable fuel- there is a finite amount
- Made of dead plants and animals
- The dead animals and plants are compressed for millons of years under the surface
- To obtain this fuel workers have to drill deep down beneath the surface
- The oil then needs to be distilled - fractional distillation
problems with crude oil include transporting it leading to damage to the enviroment and spills harming wildlife
Crude ol is a mixture of small and very large molecules. They can be seperated by fractional distillation, into fractions.
- ( 1,2,3,4 carbon molecules) fraction 1-4 - fraction fuel gas
- (65 degrees ) fraction 5-6- petrol
- (170 degrees) fraction 6-10- parrafin
- ( 250 degrees) fraction 10-14- light gas oil
- (340 degrees) fraction 14-19- diesel
- (500 degrees ) fraction 19-35- lubricating substances
- (over 500 degrees) - bitumen
cracking is important on this industrial scale because we break down the less useful liquids to create petrol which is in short supply.
Hydrocarbons are molecules made up of only hydrogen and carbon. The bigger the chain length of these the higher the boiling point. Liquid becomes thicker because of the bigger chain length. This means we need energy (heat) to break intermolecular forces.
The liquids become harder to ignite because there is lese vapour coming off them which means the flame has to get close to ignite.
Testing for alkenes and alkanes
Alkenes are unsaturated hydrocarbons having a double bond.If we shake them with bromene water , which is orange, it turns colourless as the bond adds across the double bond.
Alkanes are saturated hydrocarbons having only single bonds. These do not react with bromene which therefore stays orange. eg- ethane+bromine ------> no reaction
- Molecules which are formed by joining many smaller molecules together in a long chain are called polymers.
- The smaller repeating ones are called monomers.
- The reaction is called pollymerisation
- In industry the conditions needed are high pressure and a catalyst
- This causes the double bond in monomers to breaks and then the monomers to break and then the monomers join in a long chain
Forces of attraction have to be broken for fractional distillation
Fats repel water therefore to bind a fat and water (mayonaise) an emulsifier is needed.
- Hydrophillic - water loving head attracts the water
- Hydrophobic- water hating attracts th oil
The hydrophobic tail is attracted into the lump of oil ut the head isn't. The hydrophillic head is attracted to the water and pulls the oil on the tail into the water.
Other emulsifiers include detergent, soap, some paint,milk...which can be used in oil slicks when washing up.
When methane gas was burned waster and carbondioxide were sucked into the apparatus. This is shown by the change in the limewater from clear to cloudy which only happens when carbondioxide is present. The cobalt chloride paper turned pink which is a result of water being a product of combustion.
CH4 + 2O2--> Co2+ 2H2o
methane+ Oxygen---> carbondioxide+water
This is the equation for COMPLETE COMBUSTION because there is a plentiful supply of oxygen.
This occurs when insufficent oxygen is availible. Eg- a closed air hole on a bunsen.
CH4 + O2 ----> C + 2H2o
energy transferred = mass of substance heated x specific heat capacity x tempreture change
- Reactants- starting subtances
- Products- substances formed
Reactants -----> Products
Methane + oxygen ------> carbondioxide+ water
CH4 + 2o2 -----> Co2 + 2H20
In every chemical reaction we break bonds on one side and add bonds to another..
- If a reastion gives out energy the surroundings increase in tempreture this is called an exothermic reaction.
- If a reaction takes in energy the surroundings decrease in tempreture this is called an endothermic reaction.
- A thermochromic pigment that changes colour at 45 degrees can be a warning (on cups or mugs).
- A pigment that changes colour just above 0 degrees makes a good warning for road signs (freezing)
Most thermochromic paints change colour from colour to colourless. Thermochromic paints come in a range of colours. To get a larger range of colours they are mixed with different colours of normal acrlyic paints, in the same way you would mix coloured paints.
When the mixure gets hot the blue thermochromic paint becomes colourless so that all that is seen is the yellow acrlyic paint.
Phosphorescent pigments absorb enery from daylight. Then slowly release the energy as light ( these are someimes use in luminant watch dials). Some radioactive chemicals also glow in the dark but exposure to these may lead to cancer.
Iron ore Iron
Aluminium ore aluminium
Investigating Cement and concrete
Cement - made from heating calcium carbonate (limestone) to form clacium oxide.
CaCo3 ------> CaO + Co2
When cement is mixed with sand and water to make mortar which is used for brick laying.
When cement is mixed with sand, gravel and water it forms concrete used for construction.
Concrete is strong under compression , he squashing force, but weak under tension , the pulling force. If a heavy load is put on a concrete beam it will bend very slightly , this puts it under tension and cracks will form. To cure this concrete is reinforced with steel which is strong under tension.
Unfortunately steel rods will oxidise and rust making them weak and easy to break after contact with water this means they must be carefully put in or replaced regularly.
The limestone cycle
Calcium carbonate --------> calcuimoxide +carbon dioxide
Problems with quarrying limestone
1. Dust pollution - covering the surrounding vegatation in a layer of dust
2. Noise pollution- loud explosions etc.
3. Damage to the enviroment- destroying natural habitats
Rock types re-cap
Sedimentary- ware's away easily, the softest rock type and is mainly calcium carbonate (limestone) so will errode in acid rain.
Metamorphic- Changed forms limestone ----> marble ( under pressure and heat), still bad in acid rain but harder than sedimentary rock.
Igneous- cools slowly and forms interlocking crystals as it cools, an example of this is granite and is very hard.