Crude Oil Flashcards
Crude oil
Finite source
Liquid
Mixture of different hydrocarbons
Using crude oil’s
Different boiling points so can separate liquids into useful substances
Separated into fractions by distillation
Alkanes
Saturated hydrocarbons = single bonds
Most hydrocarbons are alkanes
Formula of alkanes
CnH(2n+2)
How many molecules in first 4 alkanes
CH4 (meth)
C2H6 (eth)
C3H8 (prop)
C4H10 (but)
Trend in properties depending on chain length of their molecules
Short chain: Low boiling point High volatility (turn into gas) Very runny Higher flammability
Long chain: High boiling point Low volatility Thick liquid Lower flammability
Fractional Distillation of crude oil
1) heated crude oil enters bottom of fractionating column as hot vapour
(hot at the bottom and cooler at the top)
2) gases move up column
3) hydrocarbons condense when reach boiling points
4) different fractions collected as liquids at different levels
How do molecules of hydrocarbons in fractional distillation?
Smallest molecules = lowest boiling points
Top of column = gases
Bottom of column = high boiling points, liquids and solids
Products of complete combustion of a hydrocarbon
Carbon dioxide and water
Product of incomplete combustion
Carbon monoxide
What happens to the vapour in hydrocarbons?
Passed over a hot catalyst
Mixed with steam and heated to a very high temperature
What is the problem with large molecules hydrocarbons?
Thick liquids or solids High boiling points Difficult to vaporise Do not burn easily Poor fuels Broken down into more useful ones (cracking)
What are hydrocarbons cracked as
Thermal decomposition
What is the positive test for an unsaturated hydrocarbon
Orange bromine water -> colourless
