1. 9G Environmental chemistry
Soils
Acid rain
Global warming

2. 9G Environmental chemistry
Soils

3. How can gardeners keep plenty of humus in their soil?
9G Making soil
Soil supports all the plant life on our planet. Where does soil come from?
How can gardeners keep plenty of humus in their soil?

4. 9G Dish the dirt!
Americans call soil ‘dirt’. But it’s not just something to clean up and throw away!
True or False?
4. The decayed residue of dead plants and animals found in soil is called musk.
1. Soil is pretty much the same wherever you go.
3. Most soils are more acidic than lemon juice or vinegar.
2. A healthy soil contains plenty of air.
5. It takes about 100 years for a few inches of good soil to form.
It’s humus you prunus! It’s dark brown and sticky and it helps to stick the soil particles together, keeping the soil fertile.
FALSE!
And how long does it take to destroy the same layer of soil? Less than 10 years.
TRUE!
Roots need a good supply of air or they die. Overwatering can remove the air from soil and kill some plants.
TRUE!
Soils vary from place to place depending on the rocks that formed them.
FALSE!
Most soils are only slightly acidic. Soils on heather moors may have a lower pH, but none are as acidic as lemon juice.
FALSE!

5. Which soil would grow the best camellias?
9G How acidic?
Camellias grow best in acid soils. Some plants prefer neutral or alkaline soils. Others aren’t fussy!
You can test the pH of your soil using a kit based on universal indicator.
Which soil would grow the best camellias?
universal indicator
soil A
soil B
soil C

6. 1. To find out the pH of a soil sample I would...
9G Growing quiz
1. To find out the pH of a soil sample I would...
a) heat it in a crucible
b) boil it with red cabbage
c) use a soil testing kit.
2. Which of these are useful mineral nutrients for plants?
a) nitrates and phosphates
b) acetates and oxalates
c) saucers and dinner plates.

7. 3. Air in soil is needed for... a) respiration in roots
9G Growing quiz
3. Air in soil is needed for...
a) respiration in roots
b) photosynthesis in roots
c) making roots rise.
4. To find the amount of water in soil I could...
a) add water until it cannot absorb any more
b) dry it in an oven and note the change in weight
c) see if seeds can germinate in it easily.

8. 9G Environmental chemistry
Acid rain

9. carbon dioxide + water carbonic acid
9G What is acid rain?
Rain is naturally slightly acidic. Why?
Because carbon dioxide in the air dissolves in the falling water to make carbonic acid.
carbon dioxide + water carbonic acid
normal rain
acid rain
So what’s acid rain?
It’s a term used for rain that is more acidic than normal.
Acid rain forms when acidic gases in the air dissolve in the rain. These gases come from burning fossil fuels.

10. Match the pH to the substance. substance pH unpolluted rain
9G How acidic is acid rain?
Acid rain is more acidic than normal rain. But how does it compare with other acids?
pH 1 pH 2 pH 3 pH 4 pH 6 pH 7
Match the pH to the substance.
substance pH
unpolluted rain
car battery acid
acid rain from a polluted area
acid in your stomach
pure water
vinegar
pH 6
pH 2
pH 4
pH 1
pH 7
pH 3

11. All of these processes produce acidic gases which cause acid rain.
9G What causes acid rain?
All of these processes produce acidic gases which cause acid rain.
Rank them in order, starting with the worst offender.
1. generating electricity
2. transport (cars, planes, trains, etc.)
3. industrial furnaces and boilers
4. forest fires, volcanoes and other natural sources
5. domestic (fires at home)
transport (cars, planes, trains, etc.)
domestic (fires at home)
generating electricity
industrial furnaces and boilers
forest fires, volcanoes and other natural sources

12. sulphur dioxide concentration
9G Meet the acid gases
The main acidic gases are:
• sulphur dioxide (SO2) • nitrogen oxides (N2O, NO, NO2)
Acidic gases in the air can cause lung problems.
deaths per day
sulphur dioxide concentration
date, December 1952
deaths per day/sulphur dioxide (ppb)
Roughly how many extra deaths occurred from the 5th to the 9th of December?
Is it fair to say that acid gases caused these deaths?

13. Acid rain can fall many miles from the source of the pollution.
9G How is acid rain formed?
Acid rain can fall many miles from the source of the pollution.
Acid gases react together in the clouds – sunlight encourages this reaction.
Falling rain dissolves the acidic gases.
Acid gases rise in the air.
Dry deposition – acid particles fall to the ground in dust.
Acid rain falls to the ground. It makes soil, lakes and rivers more acidic.
Burning fuels release acidic gases, mainly sulphur dioxide (power stations) and oxides of nitrogen (vehicles).
What problems does acid rain cause?

14. But acid rain is dangerous because it acts over many years.
9G It takes a while...
Acid rain is a dilute acid solution. The acid in your stomach is stronger and more corrosive.
But acid rain is dangerous because it acts over many years.
Think how much rain falls on a building over 200 years!
Even a slight increase in the acidity of rain could have serious effects over this timescale.
And because the changes from day to day are small, people do not notice them. Why does this make it even more dangerous?

15. It reduces the growth of plants, including food crops.
9G But the effects are serious
Acid rain reacts to dissolve away rocks such as limestone. This destroys valuable buildings.
It makes rivers and lakes more acidic. This causes problems on moors and mountains where the ground is already acidic.
It allows poisonous chemicals such as aluminium salts to dissolve in water and soil. They poison trees and fish.
It reduces the growth of plants, including food crops.

16. Match each problem with the best solution to beat acid rain.
9G Beating acid rain
Match each problem with the best solution to beat acid rain.
Acid problem
Possible solution
nitrogen oxides from car exhausts
acid gas scrubbers
acidic gases in smoke from industrial furnaces and coal-fired power stations
‘clean’ smokeless fuels
smoke from domestic coal fires
add limestone
acid rain killing lakes
fit cars with catalytic converters
fit cars with catalytic converters
acid gas scrubbers
‘clean’ smokeless fuels
add limestone

17. thousand tonnes of SO2 produced in UK
9G Hope or horror?
Is pollution getting worse – or better?
Try to match the year to the amount of acidic gas produced. We’ve added a guess for 2010.
4854
year
thousand tonnes of SO2 produced in UK
1970
1980
1990
2000
2010
6460
4854
3719
1188
875
If you drew a graph of this data, what would it look like?
Can you explain this trend?

18. So is the pollution problem getting better?
9G Good news, bad news
So is the pollution problem getting better?
Decide whether each headline is good news or bad news.
Levels of acidic gases in the atmosphere are falling.
We are developing more and more gadgets and devices that use energy.
Modern devices are more energy-efficient than old ones.
We are using cars more and more.
Governments all over the world have agreed to cut emissions of acidic gases.
What do you think? How could we do better?

19. 1. Sulphur dioxide is an acidic gas made by... a) burning scrap metal
9G Quiz
1. Sulphur dioxide is an acidic gas made by...
a) burning scrap metal
b) burning fossil fuels
c) cows as they digest grass.
2. Acid rain is caused by...
a) acidic gases in the atmosphere dissolving in falling rain
b) ozone in the atmosphere dissolving in falling rain
c) increased sunlight.

20. 3. The best way to reduce acid rain is by...
9G Quiz
3. The best way to reduce acid rain is by...
a) releasing alkaline gases into the air
b) pushing rain clouds out to sea with jet engines
c) reducing the production of acidic gases.
4. Which of the following is NOT caused by acid rain?
a) damage to buildings made of limestone
b) damage to lakes in some highland areas
c) asthma.

21. 9G Environmental chemistry
Global warming

22. 9G What is global warming?
Over the last few hundred years, the average temperature of the Earth’s oceans has been rising. This is global warming.
Why is this a problem?
Global warming increases the energy in the atmosphere, making it turbulent – more storms, more droughts, more floods.

23. How does the greenhouse effect explain global warming?
9G What about the greenhouse effect?
The greenhouse effect is a theory to explain why global warming is happening.
Light reaches us from the Sun. Some of it is absorbed by the Earth and warms it. Some is reflected back into space.
With more greenhouse gases, more infrared is reflected back to the Earth, and it gets warmer still.
Some infrared radiation is reflected back by the greenhouse gases. This makes the Earth warmer than it would be without the greenhouse gases.
The Earth gives off infrared radiation because it has been warmed by the Sun.
In the atmosphere is a layer of greenhouse gases.
How does the greenhouse effect explain global warming?
The world needs the greenhouse effect. Without it the Earth would be too cold for most organisms to live.

24. What processes produce this gas?
9G The key greenhouse gases
A greenhouse gas is a gas in the atmosphere that reflects infrared radiation back to Earth.
Do these gases act as greenhouse gases in the atmosphere? Answer ‘yes’ or ‘no’.
gas
greenhouse gas?
carbon dioxide
methane
CFCs
ozone
nitrogen oxide
yes
yes
yes
yes
yes
One of these gases in particular is on the rise, causing the ‘enhanced greenhouse effect’. Which gas?
What processes produce this gas?

25. 9G True or false?
True or False?
3. The rise in carbon dioxide in the atmosphere is probably due to human activity.
1. Carbon dioxide contributes significantly to the greenhouse effect.
2. Plants tend to increase the greenhouse effect by giving out carbon dioxide.
4. Global warming is causing a hole in the ozone layer.
CFCs are causing the hole in the ozone layer, which is letting more ultraviolet radiation reach us. This is not the same problem as global warming.
FALSE!
Again, most scientists now accept this statement.
TRUE!
Plants take in carbon dioxide during the day for photosynthesis, so they tend to reduce the greenhouse effect!
FALSE!
Yes, most scientists agree with this statement.
TRUE!