Fuels Flashcards
Why do hydrocarbons have a higher viscosity?
Because they have longer chains
What does high viscosity mean for hydrocarbons?
They are thicker and flow less easily
Why do hydrocarbons have higher boiling points?
Because they have longer chains
Why are hydrocarbons less flammable?
Because they have longer chains
What are produces when vaporised hydrocarbons are mixed with steam in a high temperature environment?
Alkanes and alkenes
What is produced when a vaporised hydrocarbon is passed over a hot catalyst?
Alkane and alkene
What type of chemical reaction is invoked with cracking?
Thermal decomposition reactions
what is crude oil made of?
a complex mixture of lots of hydrocarbon
what are hydrocarbons?
compounds that contain hydrogen and carbon atoms only
what does crude oil produce?
fuels, such as petrol and diesel
how is crude oil formed?
over millions of years, from the effects of high pressures and temperatures on the remains of plants and animals
what does crude oil contain?
molecules with rings of carbon atoms
how much of crude oil is there?
a finite resource
where can crude oil be found?
under the sea and ground
what does finite mean?
it will run out
what are reasons for separating crude oil?
Unseparated crude oil isn’t very useful
separated products are very useful
what are uses of refinery gas?
heating and cooking
what are uses of kerosene?
aircraft fuel
what are the uses of diesel oil?
cars and trains
what are the differences between hydrocarbons in each fraction?
boiling points
ease of ignition
viscosity
the number of hydrogen and carbon atoms their molecules have
what is viscosity?
how thick and sticky a substance is
what are the properties of hydrocarbons tapped from the top of the fractionating column?
low boiling point
highly volatile
easily ignited
shorter carbon chains
what happens when fuel undergoes complete combustion?
energy is given out
what is the balanced equation for complete combustion of ethane?
2c2H6 + 7o2 -> 4co2 + 6H2o
when does incomplete combustion occur?
when there is an insufficient supply of oxygen
how to ensure complete combustion occurs?
the reaction should be carried out with excess oxygen
what are the products of incomplete combustion?
carbon particulates
carbon monoxide
water
what are the problems with carbon monoxide?
toxic gas
colourless and odourless, can cause death
how does carbon monoxide cause death?
be preventing the red blood cells from carrying oxygen around the body
what are the problems with incomplete combustion?
produces carbon monoxide which is toxic and fatal
produces carbon particulates which cause global dimming and respiratory problems
what happens when fuels are burned?
the sulfur impurities in the hydrocarbons, react with oxygen to form sulfur dioxide
how is acid rain produced?
sulfur dioxide evaporates into the air. it reacts with in the clouds to form sulfuric acid. This is acid rain
what are the problems caused by acid rain?
corrodes buildings - limestone
kills vegetation
lowers the pH of large bodies of water - killing wildlife
how oxides of nitrogen are produced from car engines?
the high temperatures and pressure of a car engine causes nitrogen and oxygen from thw air to react together
what are the problems associated with oxides of nitrogen?
pollutants
produce acid rain with similar effects as So2
cause respriatory problems
what are advantages of using hydrogen in cars?
releases more energy
renewable source, can be extracted from water
disadvantages of using hydrogen in cars?
expensive, produced with electrolysis
difficult and dangerous to store
what is methane?
non-renewable fossil fuel found in natural gas
what is cracking?
breaking down large hydrocarbons into smaller more useful ones
what are the properties of the main fractions of crude oil?
some properties of hydrocarbons depend on the size of their molecules
