Paper 1 - Crude Oil and Alkanes Flashcards
What is a hydrocarbon?
Hydrocarbons are molecules that are formed of hydrogen and carbon atoms only
What is the general formula for alkanes?
CnH2n+2
What are the first 6 alkanes?
Methane
Ethane
Propane
Butane
Pentane
Hexane
What happens when fuel is burned?
Heat energy is released
How do SO2 and N02 contribute to acid rain?
- SO2/N02 react with H2O in clouds and form sulphuric/nitric acid
- this acid (acid rain), falls upon towns, corroding, buildings, and statues and killing plants by firming the soil
How does industrial process of fractional distillation, separate crude oil into fractions?
- crude oil is heated to 350°C to vaporise it.
- Gases and fractionates in column at the bottom.
- The gradient is exists: the tower is cooler at the top and hotter at the bottom.
4 vapours condensed back into liquids at their boiling points, different fractions have different boiling points, and collect at different levels of the tower - Small chain hydrocarbons have low boiling points and collect as gas at the top of the column where temperature is lower.
- Long chain hydrocarbons have high boarding points and collecting near the bottom of the tower where temperature is higher 
What is the impact of carbon monoxide?
- It is poisonous
- It replaces the oxygen in the blood with carbon
- Cells cannot aerobically respire
- Leads to: fainting, comas or death
What is the homologous series?
“Family” of hydrocarbons that all have similar chemical properties
How is crude oil formed and what of?
- microscopic plants, animals (plankton) that die and fall to the seabed
- Layers of sand and mud from on top
- Pressure and high temperatures cause oil to form
- Oil is obtained by drilling into seabed
Why are alkanes classified as saturated hydrocarbons?
- Alkanes do not have a double bond
- Alkanes have the maximum possible number of hydrogen atoms
What is the reaction between alkanes and halogens in the presence of UV radiation?
- This is known as a substitution reaction
- A halogen reacts with an alkane to form a haloalkane
- One hydrogen atom is replaced with a halogen atom
What does crude oil contain?
A mix of hydrocarbons
How is burning of hydrocarbons classified as a combustion reaction and what can it be used for?
- A reaction that burns a substance, releasing heat energy
- Useful for electricity, heating and transport
- Hydrocarbon + O2 —> CO2 + H2O
Draw the molecular structure of pentane
Draw it then google it
How are hydrocarbons represented?
- empirical formula (simplest)
- Molecular formula (actual molecular structure)
- Structural formula
- Displayed formula
How do you test for CO2?
- Below CO2 into clear lime water
- If limewater turns, cloudy, CO2 is present
What is an isomer?
Molecule with the same molecular formula as another molecule, but with a different displayed formula
What are the main uses for the fractions obtained from crude oil?
- Refinery gases - domestic heating
- Gasoline - fuel for petrol cars
- Kerosene - plane fuel
- Diesel oil - cars, lorries, vans
- (Heavy) fuel oil - ships
- Bitumen - repairing and laying tarmac
What are the properties of long chain hydrocarbons?
- High boiling point
- Low flammability
- High viscosity
What are the properties of short chain hydrocarbons?
- Low boiling point
- High flammability
- Low viscosity
What are the main fractions that are obtained from crude oil?
Coldest/Top:
- Refinery gases
- Gasoline (Petrol)
- Kerosene
- Diesel oil
- (Heavy) fuel oil
- Bitumen
Hottest/Bottom:
What is the trend in colour, boiling point and viscosity of the main fractions?
As the hydrocarbon chains become longer: the boiling point increases, viscosity increases and colour becomes darker
How do you test for alkenes and alkanes?
- Use bromine water (initially orange)
- Add hydrocarbon solution
- If solution turns, colourless, hydrocarbon is an alkene
- A solution remains orange, hydrocarbon is an alkane
What is a functional group?
Specific group of atoms or bonds within a molecule that is responsible for characteristics in chemical reactions
