Contributed by: New York State Education Department (NYSED)
NYS Alternative Assessment in Science Project (1996)

Task:

At this station, you will observe two types of interactions, and then be asked to answer some questions about the interactions.

Materials: 2 resealable plastic bags 2 twist ties 1 half teaspoon measure 1 - 50 ml graduated cylinder baking soda vinegar water paper towels safety goggles

Background:

In nature many types of matter (chemicals) interact as they come in contact with one another. With some chemical interactions no change occurs, but with other chemical interactions, change can occur.

Put on your safety goggles. Do not touch or taste any chemical. Clean up spills immediately.

1. In one of the bags, put 1/2 teaspoon of baking soda into one corner.
2. Tie off the corner of the bag with a twist tie as shown in the diagram.
3. Measure 30ml of WATER and pour it into the empty corner.
4. Remove as much air as possible and seal the bag tightly.
5. Remove the twist tie from the bag and gently mix the baking soda with the water.
6. Describe what you observed after you mixed the contents of this bag. List 2 observations.
   

7. Set the bag aside, and continue with Part B.

Part B

1. In the other bag, put 1/2 teaspoon of baking soda into one corner.
2. Tie off the corner of the bag with a twist tie as shown in the diagram.
3. Measure 30 ml of VINEGAR and pour it into the empty corner.
4. Remove as much air as possible and seal the bag tightly.
5. Remove the twist tie from the bag and gently mix the baking soda with the vinegar.
6. Describe what you observed after you mixed the contents of this bag! List two observations.

Questions:

1. In which of the bags did a chemical change occur? Circle your answer.

2. Based on your knowledge of science and your observations, explain why you think a chemical change occurred. Give 2 reasons to support your answer.

3. Based on your knowledge of science and your observations, explain why you think a chemical change occurred. Give 2 reasons to support your answer.