Alkanes and Alkenes

• Separation is done by a fractional distillation tower
• This is when you refine crude oil into parts. This is called distillation.

• The first thing they do is pour the oil in a distillation tower and start to heat it. As it heats it starts to evaporates and goes up the tower and the higher it goes the cooler it is. Because of the temperature change the gas condenses and becomes a liquid and this is how they separate crude oil and the last layer is coal.

Conversion:

• The fractions are converted into useful products
• This is done by cracking which involves breaking large hydrocarbons into smaller ones. Catalyst are used to speed up the process.
• Cracking reactions always produce two products. An alkane with a shorter chain than the original one and a short-chain alkene such as ethane.

• The second stage is conversion. Conversion is when you make the hydrocarbons smaller by cracking. After that you convert the fractions into useful products. They also use catalyst to speed up the reaction.

Example of a cracking reaction:

Decane → octane + ethane

Saturated and unsaturated compounds

Saturated compounds:

• Only have a single bond
• Full bonding potential is used
• React by substitution reaction

Unsaturated compounds:

• Have single and double bonds
• Full bonding potential is not used
• React by addition reaction

Polymerization

What is polymerization?

Polymerization is when you join molecules together to make a polymer. The small molecules that make a polymer are called monomers. There are two types of polymerization. Addition and substitution polymerization.

Addition Polymerization:

• Only 1 product
• Monomer + monomer + monomer + …… →  polymer
  

Substitution Polymerization:

• Substitution polymerization is also called condensation reaction
• Usually 2 products
• Monomer + monomer + monomer + …..→polymer + water
  

Alkanes and Alkenes

• Alkanes and alkenes are two important groups of organic molecules.
• They are hydrocarbons,which means that their molecules contains of carbon and hydrocarbon only.
• Alkanes are saturated compounds because they only have one bond
• Alkenes are unsaturated compounds because they have a double bond
• Alkenes are more reactive than alkanes because of their double bond

Some Alkanes and alkenes:

1. Methane – CH4
2. Ethane – C2H6
3. Propane – C3H8
4. Butane – C4H10
5. Ethane – C2H4
6. Propene – C3H6
7. Butene – C4H8
8. Pentene – C5H10

How do you find out if it is an alkane or alkene?

Add bromine water and if it turns colorless then it is a alkene, but if it is orange than it is a alkane.

Plastics

Definition:

A plastic can be molded or shaped into anything

• Plastic is a macromolecule which is a big molecules which is made from lots of small bits. Monomer + monomer + monomer+ ….→polymer

Examples: Bakelite, Perspex, polythene, and polystyrene etc…

In like examples: sun glasses, plastic buckets, rubrics cube etc…

2 main types:

1. Thermoplastics
2. Thermosets

Thermoplastic:

• Can be softened by heating and hardened by cooling many times and can be used MANY TIMES

Example:

• Polythene, acrylic, polystyrene

Structure of thermoplastic:

-o-o-o-o-o-o-(no cross linking)

Thermosets:

• Can be heated and molded ONLY ONCE!!!!
• Can not be recycled
• Cant change into liquid

Example:

• Bakelite, melamine, polyester, toilet seats, some jewelry

Structure of Thermosets:

Catalyst

• Catalysts are a substance that increases the rate of a chemical reaction but itself remains unchanged at the end of the reaction.
• It is used to speed up reactions
• Can be used again and again

Fuel

What is a fuel?

• A fuel is a source of energy
• Fuels are chemicals, which react with an oxidizing agent. The agent is usually oxygen

What makes a good fuel?

• Not very expensive
• Does not produce nasty or harmful gases
• The fuel must release a lot of energy
• Not a lot of smoke when burned
• Easy to get

What happens when fuel burns?

When a fuel burns it reacts with an oxidizer, then it burns and creates useful energy and a chemical product.

Combustion

• A process of burning
• A chemical change and produces heat and light
• Requires oxygen

Complete combustion:

Complete combustion is when there is a lot of supply of oxygen. The fuel is completely oxidized.

Fuel + oxygen → CO2 + water + energy

Incomplete combustion:

Incomplete combustion is when there is not a lot of supply of oxygen. The fuel is not completely burned.

Fuel + some oxygen → carbon + carbon monoxide + less energy

The activation energy barrier

Recycling

Definition:

Reuse objects that have already been used

Examples of things that can be recycled:

1. Plastic
2. Paper
3. Glass
4. Water
5. Cans

Why do we recycle?

1. Save energy
2. Save resources
3. Save money
4. Produce less waist

Fire

For a fire to bun there must be

• A fuel
• Source of energy
• Oxygen

The fire triangle is a triangle with the three things above in all sides.

Classes of fire:

Class A: ordinary materials, paper, wood, cloth

Class B: flammable liquids such as cooking oil, petrol

Class C: flammable gases such as natural gases

Class D: metals

How to prevent fires or to kill them

• For a forest fire you can put firebreaks. A firebreak is a gap in the forest like a long road where there is no fuel for the fire. A fuel can be wood, coal, petrol etc…

• A powder fire extinguisher. This is a extinguisher that covers the fire with some sort of powder and ends up killing it.

• Fire blanket to cover the fire

• Liquid carbon dioxide extinguisher. When this is released it becomes a gas and goes on the fire. Then the fire dies.

• Foam fire extinguisher. It covers the fire when you spray it.

• A stone circle

• Fire resistant material

Notes

• Crude oil is a mixture of hydrocarbons
• Carbon atoms are really important because they have an ability to join up chains, branched chains, and rings.
• Bromine solution is brown and need to know for test