Fuels Flashcards
what are hydrocarbons?
compounds which ONLY contain hydrogen and carbon
what is crude oil?
a natural resource that is a complex mixture of hydrocarbons
why is crude oil considered a finite resource? (2)
-it forms extremely slowly over millions of years
-cannot quickly be replaced
what do crude oils contain (their structure)?
molecules in which carbon atoms are in chains or rings
what are crude oils needed for? (2)
-fuels
-feedstock for the petrochemical industry
what can crude oil be separated using?
why?
fractional distillation
-different hydrocarbons have different boiling points
describe the fractional distillation of crude oils? (4)
-heated crude oil enters near the bottom of a tall fractionating column, which is hot at the bottom and gets cooler towards the top
-vapours from the oil rise through the column
-vapours condense when the temperature of the column is cool enough
-liquids are led out of the column at different heights
what happens to hydrocarbons with low melting points?
They do not condense but leave the column as gases
what are gases used for?
used in domestic heating and cooking
what is petrol used for?
used as fuel for cars
what is kerosene used for?
used as fuel for aircraft
what is diesel oil used for?
used as fuel for some cars and trains
what are fuel oils used for?
used as fuel for large ships and in some power
stations
what is bitumen?
used to surface roads and roofs
description of small molecules that are crude oil fractions?
-low boiling point
-very volatile
-flow easily
-ignites easily
description of large molecules that are crude oil fractions?
-high boiling point
-not very volatile
-does not flow easily
-does not ignite easily
one way to remember the name of the fractions?
‘Good Penguins Keep Diving For Bass
what are alkanes?
saturated hydrocarbons
-contain only single carbon bonds
describe the properties of a homologous series?
-have the same general formula
-differ by CH2 in the molecular formula of neighbouring compounds
-show a gradual variation in physical properties, such as their boiling points
-have similar chemical properties
explain why as the number of carbon atoms increases, so does the boiling point: (3)
-the intermolecular forces between alkane molecules become stronger
-more energy is needed to overcome these forces
-the boiling point increases
which formula do all alkanes fit?
CnH2n+2
when does complete combustion of hydrocarbons happen?
when there is a good supply of air
which type of reaction is complete combustion?
exothermic
equation for the complete combustion of a hydrocarbon:
Hydrocarbon + oxygen → carbon dioxide + water
when does incomplete combustion happen?
when the oxygen supply is poor
equation for incomplete combustion of a hydrocarbon: (2)
hydrocarbon + oxygen → carbon monoxide+ water
hydrocarbon + oxygen → carbon + water
what is carbon released as in incomplete combustion? (2)
fine black particles
-that are deposited as soot
what can soot cause? (2)
breathing problems and it blackens buildings
why is carbon monoxide dangerous? (3)
-toxic gas.
-absorbed in the lungs and binds with the haemoglobin in the red blood cells.
-this reduces the capacity of the blood to carry oxygen.
side effect of carbon monoxide poisoning: (2)
drowsiness, and affected people may fall unconscious or even die.
