Fuels and Earth Science Flashcards
what are the different fossil fuels
coal
crude oil
natural gas
what are fossil fuels
non-renewable resources
what are hydrocarbons
compounds that contain hydrogen and carbon only
what is crude oil an important source of
fuels for vehicles, aircraft, ships, heating and power stations
feedstock or raw materials for the petrochemical industry
what is fuel
a substance that produces heat energy when it burns
why should we use biodiesel rather than petrol and diesel
saves fossil fuels
it is made from crops like sugarcane which are renewable
biodiesel is almost carbon neutral
what does the incomplete combustion of hydrocarbons produce
carbon(soot)
carbon monoxide
water
what two gases cause acid rain
sulfur dioxide and nitrogen dioxide
what are the renewable sources of energy
solar power, tidal power, wind power, geothermal power
why can using only renewable sources of energy cause problems in the supply of electricity
many renewable energy supplies cannot generate electricity all the time and some energy supplies are unreliable/unpredictable
how is crude oil separated into simples, more useful mixtures
by fractional distillation because the different hydrocarbons in crude oil have different boiling points
what is a fraction
a group of molecules with similar boiling points and similar numbers of carbon and hydrogen atoms
how does fractional distillation work
crude oil is heated strongly to evaporate it, and the hot vapours are piped into the bottom of the column. The vapours rise through the column and cool down. Liquids of different boiling points condense at different temperatures and are piped away. Bitumen has the highest boiling point and leaves at the bottom as a hot liquid
what are the uses of petrol
it is used as fuel for cars
what is the use of kerosene
it is used as fuel for aircraft
what is the use of diesel oil
fuel for some cars and trains
what is the use of fuel oil
fuel for large ships and in some power stations
what is the use of bitumen
used to surface roads and roofs
why is a range boiling points given for each fraction
each fraction is a mixture of compounds
each compond has a different boiling point
how can you conclude that each fraction is a mixture of compounds and not a single compound
the fraction boils over a range of temperatures
what are the properties of the smaller hydrocarbon molecules
lower boiling point
low viscosity (flow easily)
easier to ignite
what is the test for carbon dioxide
bubble the gas into limewater and the limewater turns cloudy
what is the chemical test for water
add water to anhydrous copper sulfate and it goes from white to blue
what is the physical test for water
measure the boiling point of water, pure water boils at 100 degrees
what is carbon monoxide dangerous
it combines with haemoglobin in red blood cells, preventing oxygen from binding with haemoglobin. This reduces the amount of oxygen in the bloodstream causing affected people to become unconscious or even die
how is sulfur dioxide produced
it is formed when hydrocarbon fuels containing sulfur are burned. When the fuel is burnt, the sulfur reacts in the air to produce sulfur dioxide.
how are oxides of nitrogen produced
when fuels are burned in engines, nitrogen and oxygen in the air inside the engine react together due to the high temperatures in the engine producing different oxides of nitrogen.
what does acid rain do
it kills crops, makes rivers acidic and kills fish, weathers structures made of limestone and marble, corrodes metal structures and weakens them
what are the benefits of using hydrogen to fuel cars
the combustion of hydrogen only produces water
hydrogen is easily ignited and its combustion releases large amounts of energy
what are the negatives of using hydrogen to fuel cars
hydrogen is a gas at room temperature which makes it difficult to store in large amounts and so it has to be compressed under high pressure
there could be a risk of an explosion since hydrogen is highly flammable
it is expensive to produce hydrogen from water by electrolysis
what is the general formula for alkanes
CnH2n+2
are alkanes saturated or unsaturated hydrocarbons
saturated
What happens in cracking
the large alkane is heated to evaporate it. The vapours are then passed over a catalyst of aluminium oxide and heated to about 650 degrees. The alkane is thermally decomposed and smaller, more useful hydrocarbons form and these could be used as fuels or for making polymers
why do we do cracking
it produces smaller alkanes which are better fuels as they are easier to ignite
it produces alkenes which are needed to make polymers
it produces smaller, more useful products
what can cracking produce
alkane + alkene
OR
2 alkenes + H2
what is the catalyst used in cracking
broken porcelain / aluminium oxide
what are the conditions needed for cracking
high temperature and a catalyst
Saturated
molecules are saturated if all the carbon-carbon covalent bonds are single bonds
what are the first 5 alkanes
methane
ethane
propane
butane
pentane
why do alkanes have low boiling points
They have a simple molecular structure. They are made up of small molecules with weak forces between molecules and not much energy is needed to break these weak intermolecular forces.
what are the characteristics of a homologous series
they have the same general formula
they have similar chemical properties
they differ by CH2 in molecular formulae from neighbouring compounds
isomers
compounds with the same molecular formula but different structural formula
what is the general formula for alkenes
CnH2n (n>2)
are alkenes saturated or unsaturated hydrocarbons
unsaturated as the contain at least one carbon-carbon double bond
what are the first 5 alkenes
ethene
propene
butene
pentene
hexene
what happens in addition reactions
a molecule adds across the carbon-carbon double bond to give a single saturated product
why do all addition reactions have an atom economy of 100%
only 1 product is formed
what is the test for an alkene
add bromine water to the compound and shake. It goes from orange to colourless however an alkane would remain orange
what is PTFE/teflon used for
to make non stick coatings for frying pans and kitchen utensils, burette taps and stain proofing clothing and carpets
what are the advantages of polymers(plastics)
they are resistant to corrosion
they are good insulators
they can be moulded
they are lighter than other materials
what are the problems caused by non-biodegradable polymers
toxic gases are produced when polymers are burned
there is a shortage of landfill sites
there is a danger to wildlife
it causes litter/visual pollution
