Topic 7 - Organic Chemistry Flashcards
What is a hydrocarbon
A compound only containing hydrogen and carbon atoms
What is an alkane
Type of hydrocarbon containing only single bonds (so its saturated)
What is the general formula for alkanes
CnH2n+2
How do hydrocarbon properties chain depending on its length
- The shorter the chain the more runny it is (less viscous)
- shorter chains are more volatile (have a lower boiling point)
- shorter chains are more flammable
What is complete combustion
Happens when there is enough oxygen
- hydrocarbon + oxygen > carbon dioxide + water
- releases lots of oxygen
What is crude oil
- A fossil fuel formed from the remains of plants and animals
- non renewable
- a mixture of hydrocarbons, most of which are alkanes
How is crude oil seperated
Fractional distillation
Describe the process of fractional distillation
- The oil is heated until it has turned into gas and the gasses enter a fractioning column
- In the column there is a temp gradient (hottest at the bottom)
- Longer hydrocarbons have higher boiling points - they condense and drain early on
- Crude oil separated into different fractions
What is cracking
The splitting up of long chain hydrocarbons
Describe the process of cracking
- Heat long chain hydrocarbons to vaporize them
- The vapour is passed over a hot powdered aluminium oxide (catalyst)
- Long chain molecules split apart on the surface of the specks of the catalyst - catalytic cracking
- You can crack hydrocarbons by mixing the vapour with steam - steam cracking
What’s an alkene
Type of hydrocarbon containing a double bond making them unsaturated
What is the general formula for an alkene
CnH2n
How do alkenes react
Via addition reactions - the double carbon bond opens up
What is hydrogenation
- Addition of a hydrogen to an alkene - double bond opens up forming an saturated alkane
- happens in the presence of a catalyst
What is formed when you react steam with alkenes
Alcohols
How is bromine used to test for alkenes
- When orange bromine water is added to a saturated compound no reaction will happen
- If it is added to an alkene it will react causing the bromine water to decolorise
What are polymers
Made up of lots of the same molecules joined together e.g plastics
What are addition polymers made from
Unsaturated monomers
What are alcohols
- A homologous series with the functional group OH
- used as solvents and fuels
- can be made by fermentation
What properties do alcohols have
- Flammable - undergo complete combustion in air
- first four are soluble in water
What are carboxylic acids
- A homologous group with the functional group COOH e.g ethanoic acid
- they can dissolve in water - they ionise and release H+ ions- form weak acidic solutions
What is produced when a carboxylic acid react with carbonates
- a salt, water, and carbon dioxide
- e.g ethanoic acid + sodium carbonate > sodium ethanoate + water + carbon dioxide
What functional group do esters have
COO
How are esters formed
Alcohol + carboxylic acid > (acid catalyst) > ester + water
