Hydrocarbons: Crude oil and Fuels

What is a hydrocarbon

A compound that only contains carbon and hydrogen atoms

What is crude oil

Mixture of many different hydrocarbon compounds and is finite. Most hydrocarbons in crude oil are alkanes.

What is nomenculature

Naming organic compounds:

• Monkeys: 1 carbon → Meth-

• Eat: 2 carbons → Eth-

• Peanut: 3 carbons → Prop-

• Butter: 4 carbons → But-

  Pent-

• Hex-

• Hept-

• Oct-

• Non-

• Dec-

How do u draw hydrocarbons

1. Write out no. of carbons

2. Identify bond required and write

3. Carbon can only have 4 bonds

4. Add in hydrogen

What is the formula for alkane

• CnH2n+2

• Only single covalent C-C bonds

What is the formula for alkene

• CnH2n

• At least ONE double bond

Why does CH2 not exist

Only 1 carbon so double bond cannot work even if the formula fits.

How do u start numbering carbons in hydrocarbon alkenes

• From side double bond is closest to

What are the properties of long - chained hydrocarbons

• High boiling point

• Low volatility (how quick it is to evaporate)

• Thick/High viscosity (flow)

• Low flammability (smoky)

What are the properties of short - chained hydrocarbons

• Low boiling point

• High volatility

• Runny/low viscosity

• High flammability (clear/less smoky)

What are the products of incomplete combustion

Carbon monoxide and water. Is toxic, colourless and odourless.

What is the test for CO2

Turns limewater cloudy

What is the test for water

• Turns blue cobalt chloride paper pink

• Turns white anhydrous copper sulfate blue

What is the test for saturation with halogen Bromine (alkanes)

Saturated

What is the test for saturation with halogen Bromine (Alkenes)

Unsaturated as more hydrogen atoms can be added still

Explain the process of cracking [6 Marks]

Long-chained hydrocarbons are broken down using heat and a specific catalyst to form smaller, more useful, short chained hydrocarbons.

How is petrol separated from crude oil using fractional distillation [6 Marks]

• Crude oil is heated to approximately 300`C at the bottom of the column to vaporise it

• As the gases move up through the column, the temperature drops and becomes cooler

• Different boiling points mean gases condense at different points in the column. Petrol condenses near the top as it is a shorter chained hydrocarbon.

• This gets syphoned off while the rest of the vapour continue up.

• Longer chained hydrocarbons near the bottom and short chained near the top as lower BP.