What do you think will happen when raisins are put in a solution of water, vinegar (an acid) and

baking soda (a base)?

Prediction: ______

Today you are going to observe the movement of raisins in a solution and make inferences based on what you observe. Use as many of your senses as you can while making your observations. Make sure your observations are clearly written.

1.  Pour 100 ml tap water into a 250 ml beaker.

2.  Add 5 milliliters (1 teaspoon) of baking soda.

3.  Add two to three raisins.

4.  Add 15 ml vinegar.

5.  Observe what happens for several minutes.

6.  Record your observations:

Observations
Qualitative (see, hear, taste, touch, feel) / Quantitative (measurements)

7.  Add another 15 ml vinegar

8.  Again, observe the solution for several minutes. Record your observations below.

Observations
Qualitative (see, hear, taste, touch, feel) / Quantitative (measurements)

9.  Make a drawing that shows the activity of the raisins in the liquid. Be sure to label a raisin and

any other important parts. Show movement with the use of arrows.

·  Consider the following observation: The water smelled funny.

This observation is not written clearly. It doesn’t tell much about what the observer experienced.

·  Consider another observation: The solution in this activity smelled like vinegar.

This observation is written clearly. It gives a good description of what was observed and is accurate.

10. Read the following observations. Circle the letter next to the one that is the most clearly written.

A.  The raisins moved around.

B.  Three raisins with bubbles attached rose to the top of the solution.

C.  There were raisins and lots of bubbles. Both the raisins and the bubbles were moving up and down.

11.  Explain why the observation was chosen. ______

______

12. Find one observation made on the front page and rewrite it to make it more descriptive and more exact.

______

Make some inferences about your observations. Remember that an inference is a tentative (not final) explanation of your observations. Explain the activities of the raisins in the solution by completing the following statements.

13. Some of the raisins floated because ______

______

______

14. After rising, most of the raisins sank because ______

______

15. After rising, some bubbles that were attached to the raisin popped at the top of the solution because ______

______

16. After rising, some raisins turned or flipped over as they sank because ______

______

17. After a period of time, most raisins stopped rising because ______

______

18.  Some raisins did not rise because ______

______

19.  Some raisins bumped and turned around on the bottom of the container because ______

______

20. Bubbles are spherical (round) in shape because ______

______

21. Raisins with a lot of bubbles rise but raisins with fewer bubbles don’t rise because ______

______

The story below explains the activity of the raisins. However, certain key words or phrases have been omitted. Write the missing word(s) or phrase(s) that will make each sentence correct.

About Force

Raisins float and sink because of two kinds of forces. One kind of force is a lifting force called buoyancy. The second kind of force is a sinking force called gravity. When an object is placed in a liquid, the liquid and the object push on each other. In the case of the baking soda and vinegar solution, the heavier solution pushed the lighter bubbles upward. These rising bubbles created a lifting force. The bubbles accumulated on the raisins. As more and more bubbles accumulated on the raisins, there was greater ______force present.

1

The Rise (about bubbles)

Bubbles were made by a chemical reaction of the two main ingredients in the solution, ______

2

and vinegar. The bubbles consist of a gas called carbon dioxide. Since the bubbles were lighter than the

vinegar solution, they ______.

3

This action of the bubbles created a buoyant force. Sometimes the bubbles bumped into raisins

and sometimes they ______. If enough bubbles accumulated

4

on a raisin, the lifting force made by the ______caused the raisin to rise.

5

As a result, the raisins floated to the top of the solution.

The Fall

At the surface of the solution, some of the bubbles near the top of the raisins ______.

6

This happened because the bubbles were no longer surrounded by the ______.

7

Now the floating raisins had fewer bubbles. With fewer bubbles, the raisins had less ______

8

force. The raisins sank to the bottom of the container because of the lifting force was ______

9

than the sinking force.

The Flip

Some raisins flipped as they began to sink. This happened because ______

10

On only one side of the raisins popped. This caused the lifting and sinking forces to be

unbalanced. The side of the raisins that lost the bubbles began to ______. Some

11

raisins did not behave this way. They simply sank straight down, because the bubbles

______equally on all sides of the raisins. Some raisins floated to the top and

12

stayed there because there were still enough unpopped bubbles under the raisins.

The End

Some raisins did not rise at all because they were too ______. They acquired

13

some bubbles but they could not get enough lift to overcome the sinking force. After a period of

time the raisin activity stopped. This occurred because the ingredients were all used up and no

more ______were chemically produced.

14

In your own words, explain the activities of the raisins in the baking soda and vinegar solution. Include drawings if you think they will help explain your ideas. Write in third person and include a topic sentence, closing sentence and three supporting sentences.

______

______

______

______

______

______

______

______

______

______

______

______

______

______

______

Try your own investigation. Think of other objects that might act like the raisins and other solutions with gas bubbles. Plan your investigation and bring in materials you will need to do the experiment. Write your plan, hypothesis, observations, and inferences clearly in the spaces provided.

Question/Problem: ______

______

Research:

q  Density is: ______

______

q  Buoyancy is: ______

______

q  Your objects used instead of raisins are ______because ______

______

(Why did you pick these objects?)

Hypothesis: ______

Procedure: (List materials, amount of materials, and steps to do the experiment. Formatted like a

recipe.): ______

______

______

______

______

Results:

Qualitative Quantitative

1. ______1. ______

______

2. ______2. ______

______

3. ______3. ______

______

Conclusion/Analysis of Results: ______

______

______

______

______

______

______

______

______

Page 8 of 8