Organic Chemistry Flashcards
What is Crude oil?
A finite resource found in rocks. It is a mixture if hydrocarbons
How is crude oil formed?
Over millions of years from the remains of plankton which were buried in mud
What is a Hydrocarbon?
An organic molecule made of hydrogen and carbon atoms only
What are alkanes?
Saturated hydrocarbons that only contain single bonds
What is the general formula for alkanes?
Cn H2n+2
What is meant by viscosity?
The thickness of a fluid.
What happens to the viscosity of hydrocarbons as the size of the molecule increases?
It increases
Which is more viscous and why, methane or butane?
Butane because it’s molecule is larger than methane’s
What happens to the flammability of hydrocarbons as they get bigger?
It decreases
Which is more flammable and why, methane or butane?
Methane because its molecule is shorter
What happens to the boiling point of hydrocarbons as the size of their molecules increase?
It increases
Which has a higher boiling point and why, ethane or pentane?
Pentane, its molecule is larger than
Why is methane a gas at room temperature?
It is a short chain hydrocarbon so it has a low boiling point, one lower than room temperature
What is the product of complete combustion of hydrocarbons?
Carbon dioxide and water
Why do we separate crude oil?
To make use of the separate hydrocarbons
How do we separate crude oil?
By fractional distillation
What are the conditions of a fractionating column?
Hot at the bottom, cool at the top
At what temperature does a substance condense?
When it reaches it’s boiling point
Where will shorter chained molecules condense in a fractionating column and why?
At the top because they have low boiling points and it’s cool at the top
Where will long chained molecules condense in a fractionating column and why?
At the bottom because they have high boiling points and it’s hot at the bottom
What is Cracking?
Breaking long chain hydrocarbons into smaller more useful ones
What are the two types of cracking and the conditions required for them?
- Catalytic Cracking - Low temperature, low pressure, zeolite catalyst
- Thermal Cracking - High temperature and pressure
What happens as the chain length of a hydrocarbon increases?
- Viscosity increases
- Flammability decreases
- Boiling/Melting points increase
Which is more viscous: Ethane or Hexane?
Hexane
