Organic paper 2 Flashcards
✨What is a hydrocarbon
A compound of hydrogen and carbon only
✨What is a homologous group
a family of hydrocarbons who share the same general formula and similar chemical properties . They have the same functional group and gave a trend in physical properties
✨What are isomers
Isomers are compounds with the same molecular formulae but different structural formulae.
✨What is crude oil
A mixture of hydrocarbons
✨How does fractional distillation separates crude oil into fractions?
A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.
✨Name the uses of the main fraction obtained from crude oil
- refinery gas (bottled gas)
- gasoline (fuel for cars)
- kerosene (aircraft fuel)
- diesel (fuel for cars, lorries, buses)
- fuel oil (fuel for ships, power stations)
- bitumen (bitumen for roads and roofs)
✨Trend in colour, boiling point and viscosity
- the boiling point increases as the chain length increase
- the viscosity increases as the chain length increases
- the greater the chain length, the darker the colour
✨What is a fuel
A substance that, when burned, releases heat energy
✨Complete combustion goes to
Water + carbon dioxide
✨Incomplete combustion goes to
Water + carbon dioxide + carbon monoxide + carbon (eg soot/smoke)
✨Why is carbon monoxide poisonous
When it is breathed in it binds to our red blood cells, preventing oxygen from doing so. This reduces the amount of oxygen that your blood is able to transport/ for respiration
✨How are oxides of nitrogen formed
In car engines the temperature reached is high enough to allow nitrogen and oxygen from air to react
✨Sulphur dioxide in hydrocarbon fuels
The combustion of some impurities results in sulphur dioxide
✨How do sulphur dioxide and oxides of nitrogen contribute to acid rain
This gases dissolve in rain clouds to produce acid rain Affects - health of people - plants and trees - buildings
✨How is cracking carried out
the hydrocarbons are vaporised then passed over a catalyst (silica/alumina) at high temperatures (600/700 degrees)
It breaks down the long hydrocarbon molecules down into smaller ones (into shorter chain alkanes and alkenes
Cracking is an example of thermal decomposition reaction because the large molecules are converted to smaller molecules using heat
✨General formula for alkanes
Cn H2n+2
✨Are alkanes saturated
Yes because they contain only single bonds
✨Why is cracking necessary
Because the longer chained hydrocarbons occur in larger supplies than is demanded
There is little use for them - small hydrocarbons burn well + are used as fuels
✨Alkenes functional group
C=C
✨General formula for alkenes
CnH2n
✨Alkenes reaction with bromine (addition reaction)
Alkenes + bromine —> dibromoalkane
Orange/brown to colourless
✨Eg. Ethene + bromine
—> diobromoethane
✨Alkanes reaction with bromine/other halogens (substitution reaction)
Under UV light
C2H6 + Br2 —> C2H5Br + HBr
What is the functional group of carboxylic acids
O
=
- C - OH
COOH
What is vinegar
Vinegar is an aqueous solution contains ethanoic acid
Reaction of carboxylic acids with metals
Acid + metal -> salt + hydrogen
Reaction of carboxylic acids with metal carbonates
Acid + metal -> salt + water + carbon dioxide
Esters functional group
O
C - O
What is ethyl ethanoate
The ester produced when ethanol and ethanoic acid react in the presence of an acid catalyst
Naming esters
The alcohol part of the ester forms the ‘ethyl’ part of the name
The acid part of the ester forms the ‘ethanoate’ part of the name
How are esters made
They can be made by reacting an alcohol with a carboxylic acid
Description of esters
They are volatile compounds and have distinctive smells which are used as food flavourings and in perfumes
