Organic chemistry Flashcards
What is a homologous series?
A series of compounds with the same functional group and similar properties.
What is a hydrocarbon?
Molecules that are made up of hydrogen and carbon atoms only.
What is a polymer?
Large long-chain molecules made up of lots of small monomers joined together
by covalent bonds.
What is crude oil?
A finite resource found in rocks. It is a dark, smelly liquid and a mixture of different carbon compounds.
How is crude oil made
It was formed millions of years ago when remains of tiny, ancient dead animals and plants (mainly plankton) that were buried in the mud. Over time, layer upon layer of rock was laid down on top, creating conditions to make crude oil.
What are the conditions for making crude oil?
High pressure and temperature, in the absence of oxygen.
What is a saturated hydrocarbon?
Molecules with only single bonds.
What is an unsaturated hydrocarbon?
They contain at least one carbon carbon double bond.
How is coal formed?
It is formed from the remains of ancient plants which died and fell into swamps. As swamps have little oxygen, the plants didn’t decompose, instead they got buried under layers of sediment. The heat and pressure underground changed these plants first into peat and then into coal.
What is the general formula for alkanes?
CnH(2n+2)
Why does the boiling point of alkanes increase as you go up the group?
The longer the carbon chains the more contact there is between molecules, meaning they have a greater intermolecular force of attraction. This means more energy will be needed to separate the molecules.
When chains are longer what properties change?
Higher density, higher viscosity and higher boiling point.
What is fractional distillation?
a method used to seperate the mixture of crude oil into fractions.
what are fractions?
groups of hydrocarbons with similar boiling points.
how does fractional distillation work?
takes place in a fractionating column which is heated from the bottom. the vapours begin to rise up the column. fractions move up the column until they reach their condensation point. they turn into a liquid and can be collected
what is cracking?
the thermal decomposition of long chain molecules.
why do we do cracking?
because smaller hydrocarbons are in large demand while the larger ones are plentiful but not in demand.
how does cracking happen?
the large fractions of crude oil are heated to vaporise it then the vapour is either passed over hot catalyst mixed with steam and heated in high temperature.
what are the benefits of cracking?
increases supply of useful alkanes which is feedstock for plastic and reduces waste by insuring all fractions of crude oil are used (conserving precious finite recourses).
what does cracking produce?
it does not produce definite products. when long chain alkanes are decomposed they will produce an alkane and an alkene.
what is the general formula for alkenes?
CnH2n
what is the functional group for alkenes?
they have a double double carbon carbon bond (C=C)
what is the test for unsaturation?
bromine water is added.
what happens then bromine water is added to check for unsaturation?
if it is unsaturated it goes from orange to colourless.
