Fuels Flashcards
what is crude oil
complex mixture of lots of different hydrocarbon compounds of different sizes
what are chains and rings
The hydrocarbon molecules in crude oil consist of a carbon backbone which can be in a ring or chain, with hydrogen atoms attached to the carbon atoms
The mixture contains molecules with many different ring sizes and chain lengths
what is crude oil useful for
It is also a main source of raw materials (called feedstock) for the petrochemical industry and petrol and diesel
why is crude oil finite
it is being used up much faster than it is being formed
explain the process of fractional distillation of crude oil
Fractional distillation is carried out in a fractionating column which is very hot at the bottom and cool at the top
Crude oil enters the fractionating column. vapours rise
Vapours of hydrocarbons with very high boiling points will immediately condense into liquid lower down due to high temperatures, and longer hydrocarbons
Vapours of hydrocarbons with low boiling points will rise up the column and condense at the top to be tapped off and shorter hydrocarbons
recall the names of the fractions
refinery gas - bottle gas / domestic petrol - cars kerosene - aircraft diesel - cars larger fuel oil - ships / power stations bitumen - roads roofs
What are the three factors that size of hydrocarbons depend on
boiling point - As the molecules get larger, the intermolecular forces of attraction between the molecules becomes greater as there is more surface area contact between them
viscosity - ease of flow of a liquid
High viscosity liquids are thick and flow less easily
Viscosity also increases with increasing chain length
Flammable - Smaller hydrocarbon molecules are more flammable and are easier to ignite than larger molecules
what is the homologous series
groups of organic compounds that have similar features and chemical properties
The same general formula
The difference in the molecular formula between one member and the next is CH2
As the molecules get larger, the intermolecular forces of attraction between the molecules becomes greater ,more heat is needed to separate the molecules, increasing molecular size there is an increase in boiling point
what does complete combustion release
carbon dioxide and water
what does incomplete combustion release
carbon monoxide, (toxic) and carbon (soot)
what does carbon monoxide do
binds onto haemoglobin or red blood cells preventing blood from doing job of carrying oxygen leading to fainting , coma death
what does carbon do
carbon released and deposit as soot reduces air quality and makes it dirty
what is sulphur dioxide
- formed from impurities in fossil fuels when they are burnt
mixes w clouds and fall as acid rain causes lakes to become acidic killing animals and damaging trees and limestone buildings
what does nitrogen dioxide do
produced from car engines reacts with rain water to form a mixture of nitrous and nitric acids, which contribute to acid rain:
what are two advantages of hydrogen fuel
- very clean only waste is water
- hydrogen is obtained from water which is renewable and also obtained from waste product
