Chemistry

Science 9 Unit 2: Topic 2

Investigation 2-A p. 100

Problem: What physical and chemical changes occur when two solutions are mixed together?

Materials:

- Water

- Sodium carbonate

- Calcium chloride

- Filter paper

- Dilute acid

Apparatus:

- 2 test tubes

- 2 rubber stoppers

- 10mL graduated cylinder

- funnel

- beaker

- medicine dropper

- balance/scale

- petri dish

- test tube rack

- scoopula

Hypothesis: I think that … (remember to include examples of both physical and chemical change)

Procedure:

Day 1: Part 1 –

1. Label the test tubes A and B.

2. Put on your safety goggles and leave them on for the entire investigation.

3. Measure 10 mL of water using the graduated cylinder. Pour the water into test tube A. Repeat for test tube B

4. Add 1g of sodium carbonate into the water in test tube A. Stopper the test tube and shake it until all the chemical has dissolved. Place the test tube in the test tube rack.

5. Add 1g of calcium chloride to the water in test tube B. Stopper and shake the test tube until all the chemical has dissolved.

6. Pour the contents of test tube A into test tube B. Stopper it and shake it a few times. If you have a jelly-like substance, add a small amount of water, stopper the test tube again and shake it a few more times.

7. Record your observations in the chart (Part 1). Put the test tube containing the mixture in the test tube rack and rinse test tube A under running water. Place it in the test tube rack to dry.

Day 2: Part 2

8. Fold the filter paper. Place the folded filter paper in the funnel. Dampen slightly to hold it in place.

9. Hold the funnel over the beaker.

10. Pour the mixture from test tube B into the funnel. Allow all of the mixture to filter through the filter paper into the beaker. Save both the filtrate (liquid that passed through the filter paper) and the residue (material trapped in the filter paper).

11. Record your observations (Part 2)

12. Place the filter paper and residue on a labeled petri dish lid.

13. Set aside to dry. Place a piece of paper under your petri dish with your name on it to identify it tomorrow.

14. Pour the filtrate into the bottom of a petri dish and set it on the side counter at the front of the room.

Day 3: Part 3

15. Use the dropper to add five drops of dilute acid to the residue on the filter paper. Record your observations (Part 3)

16. Observe the evaporated filtrate on the front bench. Record your observations (Part 3)

Observations:

Observations

Part 1

Part 2

Part 3

Conclusion: The physical changes occurred when:

The chemical change occurred when:

Analysis:

1. What did the reaction that happened when you added the acid to the residue tell you about the residue? (1 mark)

2. What did the residue in the evaporating dish appear to be? (1 mark)

3. Describe the chemical changes in this investigation. (2 marks)

4. Describe the physical changes in this investigation. (2 marks)

5. Sometimes when solutions are mixed together an insoluble substance is formed called a precipitate. Which of the steps created a precipitate? (1 mark)