Organic Chemistry - Oils and Fuels Flashcards
What molecules are crude oils made of?
Crude oils are hydrocarbons (only made up of hydrogen and carbon)
How is the industrial process of fractional distillation undertaken?
Crude oil is heated until it boils. As a gas, it floats upwards
As the gas goes higher and further form the heat source, the temperature decreases
When a compound reaches its condensing point, it will condense into a liquid and can be collected
Groups with similar condensing temperature are known as fraction
What are the names of the main fractions obtained from crude oil and name them in order of lowest to highest boiling point?
Refinery gases Gasoline (petrol) Kerosine Diesel oil (gas oil) Fuel oil Bitumen
What is the main use of refinery gases?
Bottled gas
What is the main use of gasoline (petrol)?
Fuel for cars
What is the main use of kerosene?
Aircraft fuel
What is the main use of diesel oil (gas oil)?
Fuel for cars, lorries, buses
What is the main use of fuel oil?
Fuel for ships, power stations
What is the main use of bitumen?
For roads and roofs
Describe the trend between boiling point and viscosity of the main fractions
Low boiling points - less viscous
High boiling points - more viscous
What is the danger of fractional distillation when there is not enough oxygen around?
Incomplete combustion:
Hydrocarbons + Oxygen > Carbon Monoxide + Carbon + Water
Carbon monoxide combines with haemoglobin, meaning that they can’t carry oxygen around the body
What are the dangers of car engines?
The temperature in a car engine is high enough for nitrogen and oxygen form the air to react to form oxides of nitrogen. These oxides are also passed out through the exhaust of the car and when they get into the atmosphere, they can dissolve in the water in the air to form acid rain.
What gases are the main contributors to acid rain and what problems do they cause?
Sulfur dioxide mixes with clouds to form dilute sulphuric acid, which is very acidic.
Nitrous oxide mixes with clouds to form nitric cid, which is very acidic.
These fall as acid rain, which causes lakes to become acidic, which kills the wildlife, the trees and damages limestone buildings and statues
Describe the trends of what is produced within fractional distillation and what can be done about it?
Long chain hydrocarbons are produced the most. They are less flammable and more viscous
Short chain hydrocarbons are produced the least. They burn well and flow well.
However, long chain hydrocarbons can be cracked, which breaks them up into short chain ones.
How are long chain hydrocarbons cracked and what do they produce?
Long chain hydrocarbons are passed over a hot catalyst (silica or alumina at 600-700 degrees), which causes them to break down into smaller molecules
As some atoms are lost from molecules, they become unsaturated and can therefore form a double bond. This is how you get alkenes form the process as well as shorter chain alkanes.
