Hydrocarbons Flashcards
How is crude oil formed?
Plankton died and fell onto the sea floor.
The dead plankton were covered in mud
Over millions of years, more and more sediment built up. The enormous heat and pressure turned the dead plankton into oil and gas.
Today we drill down through rock to reach the oil and bring it up the the surface.
What is the general formula for alkanes?
CnH2n+2
What are the differences between shorter and longer alkanes?
Longer alkanes are: Have higher boiling points More viscous Are harder to ignite Burn with a smoky flame
What are the two types of cracking and how to they work?
Catalytic cracking - heat the alkanes to vaporise them and then pass them over a hot catalyst
Steam cracking - heat the alkanes to vaporise them, mix them with steam and then heat them to very high temperature
What is the general formula for alkenes?
CnH2n
Define the term “unsaturated”
A molecule that contains one or more double bonds
How do you turn an alkene into an alkane?
Alkenes react with hyddrogen at 150C in the presence of a nickel catalyst to form alkanes. This is called hyddrogenation
What happens when alkenes react with steam?
At high pressure and temperature in the presence of concentrated phosphoric acid as a catalyst, they react with steam to form Alcohols. This is called hydration
What is the functional group of alcohols?
-OH
How is ethanol made by fermentation?
- sugars are dissolved in water
- yeast is added
- the mixture is kept in a warm place at about 30C
- air is kept out of the mixture
What happens when alcohols oxidise?
They form carboxylic acids
What happens when alcohols react with carboxylic acids?
They form esters
What happens when alcohols react with sodium?
Hydrogen gas is produced
Do alcohols react with water?
No
What is the functional group of carboxylic acids?
-COOH
