organic chemistry Flashcards
what is crude oil made out of?
crude oil is a mixture of a very large number of compounds which are hydrocarbons
what is the general formula for alkanes
Cn H2+n
why are hydrocarbons burnt?
so they can be used as fuel since the reaction releases energy
what does the complete combustion of hydrocarbons produce
carbon dioxide and water
what are the properties of shorter hydrocarbons?
- less viscous
- lower boiling point
- more flammable
how are heavy fuel oils turned into smaller hydrocarbon molecules?
by cracking using a high temperature and steam
explain how fractions are obtained by crude oil in fractional distillation
- crude oil is heated to vaporise the hydrocarbons
- there is a temperature gradient in the fractionating column
- so the gases condense at different levels
- because of their different boiling points
longer chain hydrocarbons condense at the bottom as its hotter and they have a higher boiling point, and shorter chain hydrocarbons condense further up as its cooler and they have lower boiling points
what can the fractions from crude oil produce
feedstock for the petrochemical industry
what are two useful materials produced from this feedstock for the petrochemical industry?
detergents, solvents, lubricants, and polymers
what are some of the products of cracking used as and why
some of the products of cracking are useful as fuels because there is a high demand for fuels with small molecules
what does the petrol from crude oil contain and why is it removed before petrol is burned in car engines?
the petrol contains sulfur impurities and when burned the sulfur impurities produces sulfur dioxide which causes acid rain
what is the general formula for alkenes
Cn H2n
what bonds do alkenes have
a double carbon-carbon bond
what is more reactive alkanes or alkenes
alkenes
what are the products of cracking?
alkanes and alkenes
what is the test for alkenes (to distinguish from alkanes)
react with bromine water and turn it from orange to colourless (as they are more reactive than alkanes)
why are alkenes unsaturated?
because they contain two fewer hydrogen atoms than the alkane but the same number of carbon atoms