Acid Rain
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Lesson - Acid Rain
Aims:
1. Acid rain is caused manly by oxides of sulphur, nitrogen and carbon released as fossil fuels burn
2. Linking of these gases to their correct source
3. The environmental damage of acid rain
4. Acid rain can be reduced by reducing electricity use or by generating electricity in different ways
5. The effects of acid rain on soil and lakes can be reduced by adding lime products
Outcomes:
Each group will have produced a cloze exercise and set of questions about acid rain.
Needs:
Sufficient copies of the fact files
Intro:
Hand out questionnaire about acid rain and get pupils to fill it in. (5 min)
Main activity:
Working in pairs or groups, produce a worksheet plus markscheme - aimed at pupils of their own age - based on the acid rain fact file. It should have a wordfill exercise as the first question (individual groups decide whether to provide a word list or not) followed by several short response and multiple choice questions about acid rain. (40 min)
Minor activity:
Pupils re-answer the questionnaire using a different colour now that they have 'found out the facts'. (5 min)
Close:
Several groups can ask the class one of their questions. The person who answers can then ask one of their questions and so on. (5 min)
Assessment:
Formative by discussion with pupils whilst working and observation of the questions and answers they are producing. Summative by marking the questionnaires, noting the improvement of answers.
Text for fact file:
Acid Rain Factfile.
Many people get muddled up about the three main environmental problems caused by pollution of the air. Here are some of the key facts about the air pollution problem known as acid rain.
General
Water is normally pH7 ...... because there is carbon dioxide in the air, rainwater is slightly acidic
There is also sulphur dioxide in the air from volcanoes ...
... this dissolves in water to form an acidic solution
If you test rain with universal indicator paper it turns the paper orange
rainwater is therefore about pH6 (ish)
Acid rain has an even lower pH than that, pH3-4 in extreme cases
That is almost as acidic as vinegar!
Acid rain is caused by gases from burning sulphur, nitrogen and carbon
These get into the air and pollute it
The polluting gases are often blown a long way from their source ...
... causing problems to other countries e.g. Sweden
Sweden gets pollution from Europe which damages their environment
Living things can cope with natural acid rain
Main gases that cause acid rain
sulphur dioxide
nitrogen oxides (several different ones)
carbon dioxide
Sources of these gases
fossil fuels (coal oil and gas) are made from dead plants or animals
These get buried in the ground and decay over millions of years ...
... forming the coal (from plants) ...
... the oil (from dead sea creatures) ...
... and the gas (from both)
They all contain small amounts of sulphur as impurities which ...
burns to form sulphur dioxide.
Nitrogen from the air burns when temperatures are high enough ...
... like in motor vehicle engines and power station furnaces ...
... forming various nitrogen oxides
Fuels contain a high proportion of carbon ...
... which burns to form carbon dioxide
Carbon dioxide and sulphur dioxide occurs naturally ...
... in gases from volcanoes
How acid rain forms
The polluting gases spread through the air and become dissolved in raindrops as they fall through the air
What acid rain does
It dissolves calcium carbonate ...
... which is one of the chemicals in mortar so buildings are weakened
Many rocks are dissolved slowly by acid rain especially limestone ...
... which has a high proportion of calcium carbonate so ...
features of statues will be gradually corroded away, bits may fall off
gravestones will be corroded and the writing will be harder to read
buildings made of stone will gradually become damaged as they corrode
Acid rain makes streams, rivers and lakes more acidic than normal
If they become too acidic, all plant and animal life will die
Acid rain makes soil sour - too acidic to support any life
Reducing acid rain and its effects
use less electricity at home and at work ...
... so that less fossil fuel is needed to generate it
Generate electricity using alternative methods ...
... that don’t release the acid rain gases e.g. ...
nuclear power stations
wind turbines
hydroelectric schemes
Use vehicles less, walk or cycle more, especially for short journeys
Slaked lime and similar chemicals can be used ...
...to neutralise soil and lakes
It is much better to reduce the sources of acid rain than to treat the effects
End of fact file
Possible questions for questionnaire
What gases cause acid rain?
What pH is rain naturally?
Where do the acid rain gases come from?
How are the acid rain gases formed?
What specific problems does acid rain cause in the environment?
How can acid rain be reduced?
