Science at key stage 3 (Year 9)

Unit 9G: Environmental chemistry
Section 3: What causes acid rain?

Objectives

Children should learn:

that the atmosphere contains carbon dioxide from natural sources and the burning of fossil fuels, and this gas can dissolve in rainwater, causing it to be weakly acidic
that dissolved oxides of sulphur increase the acidity of rain
that oxides of sulphur in the air can arise from human activity and geological activity

Activities		Outcomes
		Children:
Ask pupils what they know about the importance of carbon dioxide in the air to plants and animals from their work on photosynthesis, and remind them that the atmosphere contains carbon dioxide from natural sources. Provide pupils with a range of solutions, eg rainwater, water with dissolved carbon dioxide, water with dissolved sulphur dioxide, and ask them to carry out tests to rank them according to pH. Help pupils make a summary of the processes involved, eg as a flow diagram. Use video clips to illustrate how sulphur dioxide and oxides of nitrogen get into the air, eg through volcanic eruptions, burning of fossil fuels, and are transported away.		identify which solutions are acidic recognise that solutions with lower pH will be more corrosive identify burning of fossil fuels, eg in vehicles, and volcanic activity as leading to acids in the environment represent, eg by drawing flow diagrams or equations, a sequence of reactions in which acid rain is formed

Points to note

Pupils will have learnt in unit 7F 'Simple chemical reactions' that oxides are formed when materials burn. This may need to be reinforced in the context of burning carbon and sulphur.
Carbon dioxide as a raw material for photosynthesis is covered in unit 9C 'Plants and photosynthesis'. It is important that pupils realise that carbon dioxide in the air is essential for food production.
Some internet sites provide information about, and pictures of, recent volcanic eruptions.
Extension: pupils will already have represented some combustion reactions by word equations. It may be appropriate to introduce symbol equations to some pupils.

Safety

sulphur dioxide is toxic and corrosive. Solutions should be left in stoppered bottles. Warn pupils with asthma not to inhale

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This unit is divided into sections. Each section contains a sequence of activities with related objectives and outcomes. You can view this unit by moving through the sections or print/download the whole unit.


	1. How are soils different from each other?
	2. What happens to rocks and building materials over time?
	3. What causes acid rain?
	4. a. What are the effects of acid rain and how can they be reduced?
	5. b. What are the effects of acid rain and how can they be reduced?
	6. a. Is pollution worse now?
	7. b. Is pollution worse now?
	8. Is global warming happening?
	9. Reviewing work

Science at key stage 3 (Year 9)

Objectives

Activities

Outcomes

Points to note

Sections in this unit