7-Organic Chemistry Flashcards
What is a hydrocarbon
A compound formed form carbon and hydrogen atoms only
What bonds do alkanes have
C-C single bonds
What r the first four alkanes
Methane,
Ethane,
Propane,
Butane
What is the general formula for alkanes
C H
n 2n+2
What does it mean that alkanes are saturated
Each carbon atom forms four single covalent bonds
What are the properties of shorter hydrocarbons
More runny- less viscous,
Lower boiling points,
The more flammable it is,
What is the equation for the complete combustion of any hydrocarbon
Hydrocarbon + oxygen —> carbon dioxide + water (+energy)
What is crude oil
A mixture of lots of different length hydrocarbons
How does fractional distillation work
The oil is heated up until it is a gas, it goes into the fractioning column. It is hotter at the bottom and colder at the top. The longer hydrocarbons have high boiling points and are condensed into liquids and drain out lower in the column. The shorter hydrocarbons have lower boiling points and condense nearer the top.
The crude oil is now separated into different fractions
What is a fraction
Separated during fractional distillation, it is a mixture of hydrocarbons that all have similar boiling points and a similar number of carbon atoms
What are the uses for oil
Provides the fuel for cars, trains, planes.
The petrochemical industry uses some hydrocarbons as a feedstock to make new compounds for things like: polymers, solvents, lubricants and detergents
What is cracking
Splitting up long-chain hydrocarbons to make shorter ones
What r the different methods of cracking
Catalyst cracking,
Steam cracking
How does catalyst cracking work
Heat the long hydrocarbons to vaporise them,
Pass the vapour over hot powdered aluminium oxide,
The long hydrocarbons are split apart on the surface of the specks of catalyst
How does steam cracking work
The long hydrocarbons are heated up and vaporised.
Mix them with steam
Heat to a very high temperature
What is an alkene
A hydrocarbon which has a double bond between two carbons in its chain
What are the first 4 alkenes
Ethene
Propene
Butene
Pentene
What is the general formula for an alkene
C H
n 2n
What is produced in complete combustion of alkenes
Water + Carbon dioxide
What is the equation for incomplete combustion of alkenes
Alkene+ oxygen—-> carbon + carbon monoxide + carbon dioxide + water (+energy)
Why is there usually incomplete combustion of alkenes
Because there isn’t enough oxygen in air for complete combustion
What type of flame is produced in incomplete combustion
Smokey yellow flame
What is the addition of hydrogen to an alkene called
Hydrogenation
What is added to an alkene to make alcohol
Steam