C7: Organic Chemistry Flashcards
How is crude oil made?
Plankton buried underwater and compressed over a long time
What does crude oil consist of?
Hydrocarbons (Molecules made from only carbon & hydrogen) of different lengths
What are the 2 types of hydrocarbons?
Alkanes & Alkenes
What are alkanes made up of?
- Single-covalently bonded carbon atoms surrounded by hydrogen atoms (we say alkanes are saturated)
- Hydrogen makes 1 bond
- Carbon makes 4 bonds
What must hydrocarbons in crude oil be separated into before they can be used?
Fractions
How does fractional distillation work?
- Hydrocarbons evaporated and rise up the fractionating column where they recondense at different heights
- Longer alkanes have higher boiling points due to more energy needed to overcome the stronger intermolecular forces, so they recondense lower down the column
- Gases at top
- Liquid and thicker oil collect in the middle
- Top = really flammable
- Bottom = really viscous
What is the equation for complete combustion?
Fuel + oxygen -> carbon dioxide + water
What is the equation for incomplete combustion?
Fuel + oxygen -> carbon monoxide/carbon + water
What alkenes have higher viscosity?
Longer ones
What alkenes are more flammable?
Shorter ones
What can hydrocarbons be used to make?
Solvents, lubricants, detergents and polymers (used to make plastics)
What are polymers made from?
AlkEnes
What is an alkene?
A hydrocarbon with at least one double covalent bond
Alkenes are unsaturated
How do we test for alkenes?
Bromine water turns from orange to colourless
This is due to the bromine atoms bonding to the alkene by breaking the double bond. The molecule has been saturated
What is a problem with crude oil?
The demand for shorter alkanes is much higher compared to longer ones
What is cracking?
Breaking longer alkanes into a shorter alkane and an alkene
What does catalytic cracking require?
-Zeolite catalyst
-Temp of 550 degrees celsius
What does steam cracking require?
-No catalyst
-Higher temperature at >800 degrees celsius
What is an alcohol?
-An organic molecule with an -OH (hydroxyl) function group
-Always ends with -ol