2. We are going to hang up a pH scale
Print out the following slides and
get your students to arrange them
in a line across the class room

17. 1

18. 2

19. 3

20. 4

21. 5

22. 6

23. 7

24. 8

25. 9

26. 10

27. 11

28. 12

29. 13

30. 14

39. Copy and complete in your book
Strong Acids 1 2 3 4
Weak Acids 5 6
Neutral 7
Weak Alkalis 8 9 10 11 12 13 14

40. Pollution
What is pollution? Discuss with the person next to you for two minutes.
We are going to focus on water pollution. What causes water pollution and why is it a problem? Discuss with the person on your other side.
Share ideas as a class.

41. Who did the dirty?
Imagine you’re an environmental officer who has been called in to investigate a concern about water pollution in Smallville.
First, read the file on Smallville...

42. SMALLVILLE is a small town surrounded by beautiful countryside
SMALLVILLE is a small town surrounded by beautiful countryside. It’s a popular activity-holiday destination for tourists.
There is a river running close to the town, which is used by fishermen to catch wild salmon and other fish. Local restaurants often include fresh fish on their menus and some local supermarkets sell the freshly caught fish. Close to the town is a forest with trails for hikers and areas where groups can camp.
The forest is full of wildlife and local conservation groups have put up bat and bird boxes to encourage these creatures to nest and breed. There are also some rare woodland plants and insects which are only found in this forest and the surrounding area. Many tourists come to Smallville to visit the forest and its wildlife.
The forest rangers take groups of schoolchildren on nature trails through the forest and the money raised from these trips is used to fund research into conserving other rare species.
The town is a historic place with many medieval buildings and churches. Lots of visitors come to the town to see the famous buildings and stonework. The town boasts several large hotels, which are fully booked for most of the year and there is a thriving community with many restaurants, bars and cafes which cater for holidaymakers.
Recently, holidaymakers and the townspeople themselves have begun to notice a change
in the local environment. Dead fish are often seen floating on the river surface, trees in
the forest are losing their leaves in summer and less wildlife is present.
Your job is to identify the environmental problems that are occurring and to discuss
the economic effects of these on Smallville and the surrounding area.

43. Water Pollution
Rivers become polluted whenever anything harmful is poured into them. Some rivers are so badly polluted that they contain no living creatures at all. River animals are sometimes killed by poisonous chemicals which are dumped in the river by industry.
They can also be killed by more everyday and less poisonous materials like fertilisers, sewage, detergents and hot water.
You will need to know:
Factories often add chemicals such as lead and copper to rivers.
Rivers and streams near farmland often have higher levels of sulphates which come from the fertilisers added to fields.

44. Follow the procedure & complete the table

45. Who did the dirty? My name is …………………………….
I am an environmental protection officer
Today's case is the study of Smallville, a natural beauty spot which we feel is under threat.
Sample
Nitrate present
Lead present
Sulphur
present
Copper present
Location of sample
(using map ) A B C D

46. Pollution investigation
Test for nitrate using a nitrate-testing strip, which will change colour in the presence of nitrate.
Test for lead by adding a few drops of potassium iodide If sulphates are present, yellow precipitate will form.
Test for sulphates using a few drops of lead nitrate. This will form white precipitate in the presence of sulphates.
Test for copper using a few drops of sodium hydroxide When copper is present, a blue precipitate is formed.

47. Complete these questions in your book using full sentences
a) Chemicals that pollute rivers can kill creatures living in the water. What will happen to the fishing industry if the fish are killed?
b) What do you think will happen to the hotels in the town if fishermen stop going there on holiday?
c) Will any other industries be affected by the fish dying? What will happen to the people who work in the hotels and cafes? What effect will this have on town?
d) Farmers can use organic fertilisers such as manure instead of chemicals. This means less chemicals can leak into rivers causing less pollution and killing less fish. Do you think farmers should use manure instead of chemicals? What about if manure is more expensive? What about if manure doesn’t give such good results (i.e. you get less crops) as using chemicals does?
e) Factories can reduce pollution by cleaning their waste water properly before discharging it into rivers. This cleaning process can be expensive. What would you do if you owned the factory?

48. Give your expert advice
Write three letters...
To the farmer
2. To the mayor of the town
3. To the owner of the factory
…advising them what they should do and why!
Extension