Chemistry C7 Flashcards
(31 cards)
Hydrocarbon definition
A compound made up of hydrogen and carbon only
Types of hydrocarbons ?
Alkanes?
Alkanes- single bonds only (CnH2n+2) 1 carbon= methane (CH4) 2 carbons= ethane (C2H6) 3 carbons= propane (C3H8) 4 carbons= butane (C4H10)
Crude oil definition?
How?
equipment?
A mixture of different length hydrocarbons
To separate crude oil we use fractional distillation
Heated through condensing column
Where in the condensing column is it hotter?
Where is it more flammable?
Where are the hydrocarbons longer?
Where is it more viscous?
Hotter=bottom Flammable=top longer=bottom viscous=bottom (viscous means thickness)
Condensing column order name/temp?
(top to bottom)
used for?
Gas=20°C-gas Petrol=70°C-cars Kerosene=170°C-planes Diesel=270°C-trucks Heavy fuel oil-ships Bitumen=340°C-roads
Test for alkenes
Use bromine water
If an alkene is present the water will turn orange to colourless
What is crude oil?
A mixture of hydrocarbons
What is crude oil formed from?
The remains of ancient biomass (mostly plankton) that was buried in mud
What is a finite resource?
One that will run out
Why is crude oil a finite resource?
Because it takes longer to form than the rate at which we are using it up
What is a hydrocarbon?
A compound made of only carbon and hydrogen
What is a general formula?
A mathematical formula which allows you to work out the chemical formula of a substance
What is an alkane?
A saturated (only carbon carbon single bonds) hydrocarbon
Name the first four alkanes
Methane, ethane, propane, butane
What is the general formula for alkanes?
CnH2n+2
How does boiling point change with the length of an alkane?
The longer the alkane, the higher its boiling point
How does viscosity change with the length of an alkane?
The longer the alkane, the more viscous (less runny) it is
How does flammability change with the length of an alkane?
The longer the alkane, the less flammable it is
What is fractional distillation?
A process used to separate mixtures of substances with different boiling points
What are the steps involved in fractional distillation?
Crude oil is vaporised, different molecules rise up the fractionating column and cool down. They condense at different points on the column.
Which molecules are collected at the top of the column and why?
Small molecules as they have the lowest boiling point.
Why is fractional distillation important?
Because the different fractions of crude oil have different uses
What is a fuel?
A substance which when reacted with oxygen releases energy
Name five fuels we obtain from crude oil
Petrol, diesel, kerosene, heavy fuel oil and liquefied petroleum gases
