C8 Fuels and Earth science Flashcards
What are hydrocarbons?
compounds containing only carbon and hydrogen
As a carbon chain increases in length, what happens to the state of matter and why?
- carbon chain increases
- gases -> liquids -> solids
- due to stronger forced between molecules
What is volatility?
how easy it us for a substance to change states of matter
As a carbon chain increases in length, what happens to the volatility and why?
- carbon chain increases
- volatality decreases
- stronger forces between molecules
-harder to break therefore change states
As a carbon chain increases in length, what happens to the boiling point and why?
- carbon chain increases
- boiling point increases
- stronger forced between molecules
What is viscosity?
-measure of how fluid(runny) a substance is
low viscosity: runny, pours easily
high viscosity: not runny, won’t poor easily
As a carbon chain increases in length, what happens to the viscosity?
- carbon chain increases
- viscosity increases
As a carbon chain increases in length, what happens to the flammability(ease to ignite) and why?
- carbon chain increases
- flammability decreases
- stronger forces between molecules
What is a homologus series?
- has the same general formula
- differ by CH2 unit
- similar chemical properties
What does saturated/unsaturated mean?
saturated - single bonds only
unsaturated - contains at least one double/triple bond
Are alkanes saturated or unsaturated?
- saturated
- no double bonds
Are alkenes saturated or unsaturated?
- unsaturated
- contains a double bond
What is the general formula for alkanes?
CnH2n+2
What is the general formula for alkenes?
CnH2n
What are the first four alkanes?
methane CH4
ethane C2H6
propane C3H8
butane C4H10
What are the first three alkenes?
ethene C2H4
propene C3H6
butene C4H8
What is a functional group?
group if atoms responsible for the properties in an organic compound
What is the functional group in an alkene?
C=C bond
What colour changes occur when bromine is added to alkane and why?
colourless + brown/orange -> brown/orange
alkanes do not react to bromine
-because they are saturated
What colour changes occur when bromine is added to alkene and why?
colourless + brown/orange -> colourless
alkenes react with bromine
-because they are unsaturated
What is crude oil?
- mixture of hydrocarbons
- mixture meaning two or more substances combined withiut being chemically bonded together
How do we seperate hydrocarbons in crude oil?
fractional distillation
Why does fractional distillation work for the seperation of hydrocarbons in crude oil?
- different hydrocarbons have different boiling points
- lowest boiling point evaporates first and condenses at cooler temperature
What are the properties of hydrocarbon molecules which condense at the coolest and hottest temperatures (top+bottom) of fractional distillation?
coolest temp/ top:
- small molecules
- low boiling point
- high volatility
- high flammability
- low viscosity
hottest temp/ bottom:
- large molecules
- high boing point
- low volatility
- low flammability
- high viscosity
What 3 things are produced/released in complete combustion of hydrocarbon fuels?
- carbon dioxide
- water
- energy released
What is a fuel?
- any substance burned in oxygen
- releases energy
- exothermic reaction
What is the order of prioritisation when balancing equations?
- metals
- non metals
- hydrogen
- oxygen
What does the incomplete combustion of hydrocarbons produce and why?
- carbon
- carbon monoxide
- carbon dioxide
- water
-not enough oxygen available for complete combustion to occur
Why is carbon monoxide a toxic gas?
-colourless + odourless
so cant be seen + smelt
- binds to haemoglobin in red blood cells
- reduced volume of oxygen carried by blood cells to cells in body
What is soot and why is it hazardous?
-solid carbon particles
-block boiker jets meaning less energy is released
-makes everything dirty
-can cause health problems if inhaled
–lung damage
–breathing difficulties
How do hydrocarbon fuels produce sulfur dioxide?
- hydrocarbon fuels burned in oxygen
- impurities -> sulfur
- react with oxygen instead
- sulfur + oxygen -> sulfur dioxide
What happens when sulfur dioxide dissolves in rain water?
-sulfurous acid formed
–acid rain
What environmental problems are associated with acid rain?
-waterways become more acidic
–increase in death of plants + animals
-kills trees
- reacts with calcium carbonage in limestone and marble
- weathering occurs
- damaging builing/ statues
How are nitrogen oxides formed in the burning of hydrocarbon fuels and why is this bad?
- at high temperatures
- in combustion engines
- oxygen reacts with nitrogen
- nitrogen oxides formed
- contributes to acid rain
- can cause photochemical smog
What are the advantages of using hydrogen fuel cells rather than petrol as fuel in cars?
- hydrogen can be obtained from water produced
- no pollutants
- only produce water as waste
- plenty of water/raw materials
What are the disadvantages of using hydrogen fuel cells rather than petrol as fuel in cars?
- electricity needed for electrolysis
- gas leaks are common if the fuel system is damaged
- hydrogen is hard to store as it is very flammable
- hydrogen is expensive to produce
- hydrogen is hard to find on the market to buy
- hydrogen requires vehicles to have bigger, stronger, heavier fuel tanks
- the elctricity needed comes from burning fossil fuels which produces CO2 so pollutants are released in the process
What is cracking?
- breaking down/ thermal decomposition
- larger, molecules (alkanes)
- into smaller, useful ones (some alkene)
Why is cracking necessary?
-shorter chain molecules are more useful
-more demand for shorter chain molecules
-reduced amount of long chain molecules
-produces alkenes
–used to make polymers
What gases formed the Earth’s early atmosphere produced by volcanoes?
gases produced by volcanoes
- CO2
- H2O
- NH3
What was the Earth’s early atmosphere thought to contain?
- little/no oxygen
- large amounts of CO2
- water vapour
- small amount of other gases
How were oceans formed?
- over a billion years the earth started to cool
- lower temp means water vapour could condense into rain
- over a few hundred million years of rainfall oceans formed
How did the formation of oceans cause CO2 levels to decrease?
- plants evolved in the oceans
- photosynthesis in the plants removed CO2 from the atmosphere
- causing the % to decrease
How did the formation of oceans cause CO2 levels to decrease? (CO2 is soluble)
- CO2 begun to dissolve in the rain and oceans
- marine organisms began to evolve on Earth
- some adapted to use CO3 dissolved in the water
- created exoskeletons/shells (eg crabs)
- marine organisms then died
- sink to the bottom of the sea and build up and form sediment
- sediment compacted overtime to form carbonate rocks eg limestone/chalk
What is the test for oxygen?
- glowing splint
- reignites
How did levels of oxygen gradually increase on Earth?
- growth of primitive planta
- photosynthesis
- releases oxygen so gradual increase in %
Describe the green house effect and name the gasses involved
CO2, CH4, H2O
- short wave EM radiation from the sun is absorbed by the Earth’s surface
- short wave radiation is re-emitted as long wave IR radiation
- some IR radiation reflected back into space
- greenhouse gases absorb the reflected IR radiation and re-radiate it in all directions including back towards the Earth
since the radiation is IR, warming if the surface of the Earth is a result
What does evidence of atmospheric CO2 concentration and temperature change over time show us?
CO2 causes global warming
- as CO2 conc increase global temperatured increase
- CO2 is causing global warming
CO2 doesn’t cause global warming
- as CO2 conc increases global temperatures increase but fluctuates
- so this does not prove evidence CO2 increase is causing the Earth’s temperature to rise
- as CO2 conc increases global temperatures increase
- but there are other factors that may cause the increase in global temperatures
What is the Earth’s current atmosphere?
- nitrogen (mainly)
- oxygen
- water
-argon and other gases
How does farming contribute to climate change?
- livestock and rice release methane
- methane is a greenhouse gas
- increasing population means increasing demand for more farms
- more farms means more methane
How does burning fossil fuels contribute to climate change?
- more CO2
- more IR radiation absorbed and re-emitted
- more global warming
How can we mitigate (lessen) the effects of climate change?
-personally
–reducing carbon footprints
–choosing options thats do not involve fossil fuels eg less driving less heating
-governmental
–investigating in renewable energy resources
-new technology
–eg the Thames barrier is designed ti prevent flooding
