What Matter is Made Of Observing and distinguishing between physical and chemical changes
Part 1 Carry out the following short tasks and find out if a physical or a chemical change is taking place. Copy and complete this table.
Predict: Will it be a chemical or a physical change?
Activity
Add drops of water to a teaspoon of salt
Add drops of vinegar to a teaspoon of baking soda
Heat some candle wax on a metal lid (do not let the wax catch fire)
Heat a cracker in a Bunsen burner flame
Heat a piece of steel wool in a Bunsen burner flame
Part 2
1. Place some ice cubes in a sealable plastic bag. Measure the mass of the ice cubes and the bag. Set the bag aside until the ice cubes have melted.
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2. Predict whether the total mass of the bag and the ice will have increased, decreased or stayed the same.
3. Find the mass of the plastic bag once all the ice has melted. 4. Explain your result. Is this a physical or a chemical change? Explain your conclusion.
Part 3
1. Pour 20 cm3 of vinegar into a large sealable plastic bag and find the mass of the bag and the vinegar.
2. Measure out 5 g of baking soda and wrap the baking soda in a small sheet of tissue paper. Find the mass of the tissue paper and the baking soda.
3. Calculate the mass of the tissue paper and the baking soda plus the mass of the vinegar and the sealable bag. Record the total mass in your Portfolio.
Ahhhh, fizz
When you open can of fizzy drink, does the mass of the drink increase, decrease or stay the same? Is there a chemical or a physical change taking place?
z Fig. 9.5.3 A can of fizzy drink being opened 167
4. Drop the tissue paper into the bag of vinegar and seal it quickly. Before you do this, predict whether the total mass of the bag, the vinegar, the tissue paper and the baking soda will have increased, decreased or stayed the same.
5. Once the reaction has stopped, find the mass of the bag. Explain your result. Is this a physical or a chemical change? Explain your conclusion.
6. Why is it recommended that you use a larger bag?
Fig. 9.5.2
Ice cubes melting
Observations
Physical or chemical change?
Explain why it is an example of a physical or a chemical change
