Page ______
A MATTER OF CHANGE
Acid precipitation involves many different changes in matter. For example, within the water cycle, the water on the earth’s surface changes from a liquid to a gas in the process of evaporation. These water vapour molecules may then condense back into a liquid forming rain or they may freeze to form ice. In addition, other molecules such as carbon dioxide, sulphur dioxide and nitrogen oxide react with the water molecules in the water cycle to form new substances causing the formation of acid precipitation. Some of these changes occur physically while others involve more complicated chemical processes. In this investigation, you will distinguish between physical and chemical changes that occur in the formation of acid precipitation.
Objective Students will …
1. compare physical and chemical changes
2. identify examples as physical or chemical changes
3. explain how matter can form new substances through physical and chemical changes
Materials:
metal pan
forceps or beaker tongs
8 ½ inch X 11 inch sheet of paper
matches
safety goggles
Activity 1: What’s Your Idea?
1. Identify two safety precautions that must be followed when using matches and fire.
a.
b.
Chart 1: The Effects of Change on the Properties of Paper
Notes / Physical or Chemical ChangeOriginal paper properties / X
Prediction of properties when paper is torn / X
Observed properties of torn paper
Prediction of properties when paper is burned / X
Observe properties of paper when burned
In the investigation, you modelled a physical change and a chemical change. Predict the difference(s) between physical changes (PC) and chemical changes (CC). Use evidence from the investigation to support your response.
PC=
CC=
Activity 2: Identifying Changes Read page ______in Prentice Hall: Science Explorer, Chemical Building Blocks.
2. How would you modify your prediction of physical and chemical changes based on the information you gathered?
PC=
CC=
3. Brainstorm with your neighbour the different types of evidence for chemical reactions.
Examples of Chemical Changes Examples of Physcial Changes
4. Observe the teacher demonstrations. Complete Chart 2, “Types of Change”.
Chart 2: Types of Change
Demonstration / Type of Change(Physical or Chemical) / Justification or Evidence
How
Zinc is added to vinegar
Wooden splint broken in half
Seltzer tablet is crushed
Crushed seltzer tablet is added to water
Salt water is evaporated over heat
Activity 4: Physical and Chemical Changes in Acid Rain
9. Study the diagram, “Acid Rain Formation” and identify each step as a PC or CC and justify your answer using information from the lab and text.
Analysis
1. Determine whether physical or chemical changes are responsible for the formation of new substances. Use information from the investigation to support your response. ______