Organic Chemistry Flashcards
What two structures can carbon form?
- giant macromolecular structures
- simple molecular structures
What are the natural polymers?
- DNA/RNA
- proteins
- lipids
- carbohydrates
What is crude oil?
A mixture of hydrocarbons
What is a homologous series?
A family of organic compounds with:
- similar chemical properties
- the same general formula
- the same functional group
Give the names of the two homologous series for GCSE:
alkanes
alkenes
What is the life form which forms crude oil?
Aquatic life (ancient biomass)
What is a hydrocarbon?
A compound containing only carbon and hydrogen
What is the functional group for Alkanes?
Single bonded carbons
Saturated
What is the general formula for Alkanes?
C n H 2 n+2
What are the first four members of the alkane group?
methane, ethane, propane, butane
What is the functional group for alkenes?
Double carbon bond
Unsaturated
What is the general formula for alkenes?
C n H 2n
What are the first four members of the alkene group?
Ethene, propene, butene, pentene
What are fractions?
The different groups of hydrocarbons separated during fractional distillation
What are the different fractions?
natural gases (methane, ethane, propane, butane)
liquids (petrol, diesel, kerosene, fuel oil)
solid (wax, butamen)
What is kerosene used in?
aeroplane fuel
What is the structure of a hydrocarbon?
Simple molecular structures
What is the bonding in a hydrocarbon?
Covalent bonds between atoms but weak intermolecular forces between molecules
What is the relationship between the size of the hydrocarbon chain and the boiling point? Why?
As the length of the hydrocarbon chain increases. so does the boiling point. This is since the IMFs increases as there are more electrons.
What is the relationship between the size of the hydrocarbon chain and the flammability?
As the length of the hydrocarbon chain increases, the flammabiity decreases.
What is flammability?
The ability to burst into flames
What is the relationship between the size of the hydrocarbon chain and the viscosity?
As the length of the hydrocarbon chain increases, the greater the viscosity.
What must be done to crude oil for it to be of any use?
Processed or refined in an oil refinery
Describe how fractional distillation works:
1) Crude oil is boiled to 450 degrees and pumped into the bottom of a fractionating column, where it vaporises
2) The column is very hot at the bottom but much cooler at the top (temperature gradient). As the vaporised oil rises, it cools and condenses.
3) Heavy fractions (containing large molecules) have a high boiling point and condense near the bottom of the column
4) Lighter fractions have a lower boiling point and condense further up the column
What is naptha used for?
As a chemical feedstock and diluting diesel
What type of reaction is the combustion of alkanes?
Oxidation as the addition of oxygen occurs
What is cracking?
The decomposition of long chain alkanes to make short chain alkanes and an alkene
Why is cracking conducted?
- high demand for short chainlength hydrocarbons which are used as fuels
- demand for alkenes, needed to make polymers
- crude oil contains lots of long chainlength alkanes which aren’t useful
What are the two types of cracking?
- catalytic cracking
- steam cracking
What is catalytic cracking?
Hydrocarbon vapours passed over a hot powedered catalyst e.g. Aluminium Oxide at 450 degrees
What is steam cracking?
Mixing long chainlength hydrocarbons with steam and heating to a very high temperature
What is the general fromula for a cracking reaction?
Long Chain hydrocarbon = short chain alkane + alkene
What is the test for unsaturation (alkene)?
Add orange bromine water to alkene smaple and the orange solution will turn colourless if an alkene is present
What is the relative reactivity of a saturated and unsaturated molecule?
Unsaturated is more reactive than saturated
What is viscosity a measure of?
The ability for molecules to slid past each other
