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What is a pollutant
A substance present in air that can cause harm to humans and the environment
Pollutants can be in the form of:
Solid particles
Liquid droplets
Gases
Can pollutants be natural or man made?
Both
What is a greenhouse gas
A gas that absorbs heat in the atmosphere and prevents heat from escaping into space, keeping the Earth warmer
What type of greenhouse gas is CO2
Non-toxic
How is CO2 produced? (NATURALLY)
Natural processes:
Volcanic eruptions
Respiration of animals
Burning or decay of organic matter
Why has the amount of CO2 in the air been increasing at an alarming rate since the Industrial Revolution?
Due to the burning of fossil fuels
What are the three fossil fuels?
Coal
Oil
Natural Gas
What are fossil fuels primarily made of
Carbon and hydrogen
How do fossil fuels contribute to CO2 emissions?
They react completely with oxygen in air during combustion to produce CO2 and water vapour.
Represent this combustion reaction as a word equation
hydrocarbon + oxygen → carbon dioxide + water vapour
The industrial production of what else is a main contributor to the emission of CO2
Cement
Why does the concentration of CO2 in the atmosphere fluctuate between winter and summer
Because of seasonal variation in photosynthesis
How many extra million tonnes of CO2 are produced into the air because of the burning of fossil fuels
5000 million tonnes
What absorbs CO2 but is unfortunately being destroyed
Tropical rainforests
What can dissolve some of this extra CO2
oceans (not all CO2!!)
What happens to the rest of the CO2
It stays in the atmosphere, upsetting natures balance
What are other substances present in the atmosphere which are also greenhouse gases
Water vapor
Methane (CH4)
CFCs
Why is the level of CH4 (methane) rising
Due to an increase in:
Animal farming
Rice farming
Landfill sites
Without greenhouse gases, what would happen to our planet
It would be covered in ice with average temperatures 35C lower than at present
Does the temperature of earth have more to do with the greenhouse effect or our proximity to the sun
Greenhouse effect
Explain the greenhouse effect
Radiant energy from the sun are sent to earth as short infra-red waves. These warm the Earth.
The Earth then radiates this heat energy back into spaces as longer infrared waves.
However, greenhouse gases like carbon dioxide and water vapor in the air absorb some of this heat and send it back toward Earth.
This traps warmth, similar to how a greenhouse keeps plants warm.
Can infra-red radiated travel freely through the air surrounding the earth
No, unlike sunlight
What does an increase in greenhouse gases cause
A greater greenhouse effect → global warming
What do increasing global temperatures cause?
Polar ice-caps to melt and sea levels to rise
Low-lying areas of land to submerge under the sea
A change in climate and weather patterns all over the world. Extreme weather events (eg hurricanes and cyclones) would be more frequent.
Some agricultural areas will cease to produce crops and become deserts
Some species that cannot adapt with climate change (loss of natural habitat) will die out
What are tropical areas experiencing more of due to climate change
frequent and destructive storms and floods
To stop the increase in global temperature and stabilize atmospheric carbon dioxide concentration, how much do carbon dioxide emissions need to be reduced by
70-80%
How can this be done
less consumption of fossil fuels
Using renewable sources of energy
Reduce reliance on cars
More energy efficient buildings
Improved power plant efficiency
Planting more trees
Kyoto protocol
UN climate change conference
What is the Kyoto Protocol (1997)
The world’s primary international agreement on combating global warming. 100 counties committed to reduce their emissions of CO2 and 5 other greenhouse gases
What is the UN climate change conference
A discussion on the way forward on many issues including curbing CO3 production
What are the properties of carbon monoxide (CO)
Colourless (gas)
Odorless (gas)
Non-irritating
Very poisonous
What is carbon monoxide a product of?
Incomplete combustion of fuel - when a natural gas, coal or wood burns in a limited supply of air
Approx. how much CO is emitted into the atmosphere each year?
350 million tonnes
What is a major source of CO
Vehicular exhaust
Do all cars (petrol, diesel) produce CO
Yes
Do they check if car engines are producing CO at an acceptable level
Yes, in the VRT
What is another way CO is produced
From cigarette smoking
How does CO prevent the uptake of oxygen
It readily combined with haemoglobin in the red blood cells to form carboxyhaemoglobin
(doesn’t let oxygen bind with the haemoglobin → blood is not oxygenated→ oxygen is not carried around the body)
Does CO permanently bind with red blood cells
YES
Why do we say that CO “wastes blood”
Because it does not allow for the usual transfer of oxygen and carbon dioxide (gas exchange)
What does a shortage of oxygen make a person feel
Headache
Dizziness
Sluggishness
What level of CO in the air causes death
0.1%
How is CO removed (vehicles) (3)
Catalytic converters are fitted to the exhausts of many cars. The catalysts will oxidize carbon monoxide in the exhaust gases to CO2 (these convert CO to CO2 - not all though)
New fuels may be used in the future - Some fuels (eg alcohol) burn more cleanly than hydrocarbons
Vehicle engines can be tuned to take in more air and produce only CO2 and H2O - Unfortunately this increases the formation of NOx compounds (oxides of nitrogen)
What is a hydrocarbon
A hydrocarbon is a compound made up of only carbon (C) and hydrogen (H) atoms.
Methane (CH4)
What is a combustion reaction
A chemical reaction in which a substance reacts rapidly with oxygen with the production of heat and light
What do the products of combustion of a hydrocarbon depend on
Whether the combustion reaction takes place in a:
Plentiful supply of oxygen
Limited supply of oxygen
What are all fossil fuels made up of
Hydrogen and Carbon
What are compounds made of H and C called
Hydrocarbons
Hydrocarbon examples
Natural gas (methane)
Petrol and diesel (crude oil)
Wax
Diagram for determining what products are given as methane is burning
Process + Observations
Methane is it, air pump is switched on
A colourless liquid condenses in the U-tube. This can be tested using anhydrous copper (II) sulphate which turns from white to blue (to test water was produced)
Limewater turns milky (white precipitate) showing that carbon dioxide is produced
Word equation go summarize this
hydrocarbon + oxygen → water vapour + carbon dioxide
Chemical equation for when a methane buns in a plentiful supply of oxygen
What two products (ONLY) produced show that a hydrocarbon has undergone complete combustion
Carbon dioxide and water - ONLY!!
Fuels undergo ______ ______ when there is a plentiful supply of oxygen
Complete combustion
Fuels that burn with what flame give off the most heat energy possible
Blue flame
Why should you repeat this experiment without the fuel burning
Burning the fuel introduces more carbon dioxide and water vapor, which are already present in the air. Ensures accurate results
What difference will there be in the experiment
It will take much longer for the indicators to show a change
What is incomplete combustion
When a fuel does not burn in a sufficient amount of oxygen
What flame does it burn with in this case
A yellow same
What are the products of incomplete combustion
Unburnt particulate carbon called soot (from flame)
Carbon monoxide
Water vapour
Chemical equation for incomplete combustion of methane
Compare between complete and incomplete combustion on these points:
Ok
Amount of oxygen available
Complete: plentiful supply of oxygen
Incomplete: limited supply of oxygen
Colour of flame
Complete: clean blue flame
Incomplete: yellow sooty flame
Products evolved
Complete: Carbon dioxide, water vapour
Incomplete: Carbon monoxide, water vapiur
Amount of energy released
Complete: Most heat energy released
Incomplete: Less heat energy released
Name the following properties of Carbon Dioxide and Carbon monoxide
Ok
Appearance
Carbon dioxide: colourless
Carbon monoxide: colourless
Odour
Carbon dioxide: Odourless
Carbon monoxide: Odourless
Effect on blue litmus
Carbon dioxide: turns damp blue litmus red (acidic oxide)
Carbon monoxide: no effect on litmus (neutral oxide)
Bubbling through lime water
Carbon dioxide: turns like water milky
Carbon monoxide: no reaction with like water
Bubbling through sodium hydroxide solution
Carbon dioxide: reacts with sodium hydroxide (neutralization reaction)
Carbon monoxide: no reaction
Reducing agent
Carbon dioxide: no
Carbon monoxide: yes
Combustion
Carbon dioxide: does not burn, used to extinguish fires
Carbon monoxide: burns with bright blue flame to give CO2
Toxicity
Carbon dioxide: Toxic at very high concentrations
Carbon monoxide: toxic at very low concentrations
What is the test used to distinguish between carbon dioxide and carbon monoxide
Bubbling them through calcium hydroxide (limewater)