Topic 8 Flashcards
hydrocarbons
compounds that contain only H2 and C
fossil fuels
fossilised remains of deceased plants or animals formed over millions of years
crude oil
non renewable recource
mixture of a larger number of compounds
mixture of hydrocarbons and isnt useful until seperated
how crude oil is made
sea animals/ plants die and fall teh the sea bed
layers of sand and mud form on top but plants/animals dont decay
pressures and high temperetures cause them to turn into crude oil
this proccess takes millions of years
hydrocarbons can be arranged in chains and rings
each carbon atom can form 4 covalent bonds
each carbon atom can be arranged in different ways
crude oil uses
vehicles
aircraft
ships
heating
power stations
feedstock or raw materials for the petrochemical industry
fractional distillation
A - water is evaporating as it has a lower boiling point then ink so it turns to water vapour
B - the water condenses back into liquid because it cools
as boiling point increases
it becomes darker
longer hydrocarbon
hot oil is fractioned…
near the bottom
at the top of the column
lower boiling point…
-hydrocarbon chain lengh is shorter
- size of molecules are smaller
- so fprces between the molecules are weaker
- less energy needed
-there are less intermolecular forces of attraction
bottom of the column
higher boiling point
- hydrocarbon chains are longer
- size of molecules are bigger
- there are more intermolecular forces of attraction
how is crude oil fractioned
-crude oil is heated to make a vapour
- vapour rises up the column
- the column is notter at the bottom and cooler at the top
- hydrocarbons condense at different temperatures, depending on their boiling points
fractional distillation steps
-crude oil is heated to make a vapour
- vapour rises up the column
- the column is notter at the bottom and cooler at the top
- hydrocarbons condense at different temperatures, depending on their boiling points
fractional distillation of crude oil
petrol - 25-60
naphtha - 60-180
kerosene - 180-220
diesel - 220-250
fuel oil - 250- 300
lubricating oil - 300-350
bitumen more more than 350
viscosity
high - thick
low- runny
volatility
measure of how easily liquid turns into vapour
e.g. nail polish has a high volitality
flammable
easily ignites
longer chains mean
more viscos
less flammable
less volatile
high boiling point
what’s a homologous series
- differ by CH2
- same chemical properties but differ in physical properties e.g. gradual variation in boiling/ melting point
- general formula Cn H2n+2
neumonic
Monkeys eat peanut butter
complete combustion
- burning
- exothermic reaction and oxidation
- heat energy exits/ is released
- petrol methane cooking gas are examples of fuels
- burns in abundance of oxygen ( complete combustion)
- co2 and h20 produced
In combustion…
hydrogen in the hydrocarbon fuel is oxidised and forms water ad the carbon is oxidised to form CO2
test for water
blue cobalt paper turns pink
carbon monoxide
colourless odourless tasteless
incomplete combustion
- insignificant amount of oxygen but it still undergoes an incomplete reaction
incomplete combustion of methane
carbon, water vapour and CO2
2ch4 -> 302+ 2CO + 4H20
effects of combustion
water vapour, CO2, carbon monoxide
why is carbon monoxide toxic?
-colourless, tasteless, odourless gas
-It is absorbed in the lungs and binds with the haemoglobin in the red blood cells. This reduces the capacity of the blood to carry oxygen. Carbon monoxide causes drowsiness, and affected people may fall unconscious or even die.
incomplete combustion ( lmited supply of o2) caused by
- blocked burner jets
- poor maintenance
soot
can make buildings dirty
carbon particles in the air
can cause respiratory problems for people:
- breathing issues
- inhaling aggravated asthma
- bronchitis
- severe respiratory illness that can restrict ability to carry out normal activites
why is cracking necessary
produces smaller chains of alkenes that are used for fuel e.g. petrol
more useful
greater demand
most alkenes produced are used to make plastics
thermal decomposition - cracking
high temps ≈ 750
high pressure ≈ 76
man made changes in the atmosphere
- agriculture
- rice paddies / cow farts
- burning fossil fuels
- deforestation
natural process that contribute of changes in the climate
- volcanic eruptions
- solar output
- orbital theory
atmosphere pollutants
- H20 (g)
- carbon monoxide
- carbon dioxide
- nitrogen dioxide
- nitrogen monoxide
- sulfur dioxide
SO2
sulfur dioxide
acid rain
CO
carbon monoxide
binds to haemoglobin and blocks oxygen
CO2
greenhouse gas
NO
nitrogen monoxide
irritation of respiratory system/ make existing respiratory problems worse
NO2
nitrogen dioxide
- acid rain
- respiratory problems
particulates
eye iritation, respiration problems, global dimming
water vapour
greenhouse gas
effect of acid rain
chemical weathering - erodes limestone and marble buildings
makes river + soil acidic - harms organisms e.g. fish
damages trees - destroys the chlorophll so plants cant photosyntehestise
car engine
extremely hot
temperatures high enough for nitrogen from the air to react with the oxygen producing nitrogen oxides
production of sulfur dioxide
most fuels are hydrocarbons
lots of impurities are also present
often sulfur
reacts with oxygen in the air to produce sulfur dioxide
S + O2 -> 2NO
early atmosphere
temp 400 or higher
95% CO2
4% water vapour
traces of nitrogen, ammonia and methane
current atmosphere
temp 20
78% nitrogen
21% oxygen
traces of CO2, H2o g, ammonia, methane
how life started
1 earth is a ball of molten rock. no atmosphere is present
2 earth is still too hot for any surface water its surface is covered with volcanoes
3 earth starts to cool down water vapour begins to condense and oceans are formed
4 life begins in the oceans. Simple cyanobacteria use co2 in photosynthesise. Ozone forms and oxygen levels start to rise
5 land plants start to appear. oxygen levels rise rapidly
6 animals evolve due to the increase in oxygen
what effect does atmosphere have on temperature on earth
insulates heat increasing temp
which ghgs keep the earth warm
co2, h2o (g) , ch4
the greenhouse effect
- short wavelength from the sun passes throrogh the atmosphere and warms earth
- increasing the levels of co2 increase the amount of heat retained causing the atmosphere and the surace to warm
- Infared (long wavelength) radiation is emitted by the earth and most escapes into space but the same infared radiation is absorbed gases such as co2 and h20 and ch4 and this is released back to the earth keeping radiate the earth warm enough to sustain life
incomplete reaction
carbon , wate and carbon monoxide
co2 dissolvinf in sea
decreases co2
how is SO2 formed
sulfur burns at the same time as the hydrocarbon
sulfur reacts with oxygen
sulfur dioxide gas which is acidic and dissolves into clouds
Explain how the greenhouse effect is caused by the gases produced by the complete
combustion of diesel oil.
CO2 and H20 g produced which are radiated from earth and re absorbed back into the atmosphere
Explain how the student could modify the equipment to prove that water is produced by
burning candle wax.
reverse tubes so that gas must have come from the candle not the limewater
Explain why the incomplete combustion of pentadecane can produce carbon monoxide
as one of the products.
not enough oxygen to turn all the carbon into co2
why wait cool oxygen tank
the gas has expanded when it is hot
