Fuels From Crude Oil Flashcards
How can a mixture of liquids be separated?
Distillation
What are fractions?
Hydrocarbons with similar boiling points separated from crude oil
What are hydrocarbons?
Molecules with only hydrogen and carbon
What is the general formula of alkanes?
CnH2n+2
What are alkanes?
They contain as many hydrogen atoms as possible in each molecule we call them saturated, they have single bonds
What is the molecular formula of butane?
C4H10
What is fractional distillation?
A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing and collecting the liquids
Where are the hydrocarbons with the lowest boiling points collected?
The top of the fractioning column
What is the fractioning column like?
Hot at the bottom and get cooler going up
What is the difference between simple distillation and fractional distillation?
Simple distillation is done in steels by heating the mixture to different temperatures and fractional distillation is done continuously by vaporising the mixture and condensing the fractions at different temperatures
How does the fractioning column work?
There are many trays with holes to allow gases through. The vapours move up the column getting cooler as they go up the hydrocarbons condense to liquids when they reach the level that is at their boiling point. Different liquids collect on the trays at different levels and there are outlets to collect the fractions
Where are the fraction with the highest boiling points collected?
The boo tow of the column
What are fractions with low boiling ranges like?
Low viscosity; runny
Very flammable, ignite easily
They burn with cleaner flames, produce little smoke
Very useful fuels
Why are different hydrocarbons collected at different levels of a fractioning column?
Different hydrocarbons have different boiling points so they condense at different temperatures
What properties would you expect for a fraction that is collected one third of the way up a fractioning column?
Medium high boiling point, quite viscous, not nerdy flammable, burns with quite a smokey flame
What happens when hydrocarbons burn completely in enough air?
They are oxidised to carbon dioxide and water
What does incomplete combustion produce?
Carbon monoxide, carbon, soot and unbutton hydrocarbons called particulates
What is the word equation for the complete combustion of ethane?
Ethane+oxygen–>carbon dioxide+water
Fossil fuels contain sulphur compounds which burn to produce what?
Sulphur dioxide
What does sulphur dioxide cause?
Acid rain
At high temperature what may oxygen and nitrogen form?
Nitrogen oxides
What do nitrogen oxides cause ?
Acid rain
What does carbon dioxide cause?
Global warming> melts sea caps> flooding
What is the greenhouse effect?
The greenhouse effect works like this: Energy arrives from the sun in the form of visible light and UV radiation. The Earth then emits some of this energy as infrared radiation. Greenhouse gases in the atmosphere ‘capture’ some of this heat, then re-emit it in all directions - including back to the Earth’s surface.
