Density Bottles

INTRODUCTION

This is an experiment that can introduce the concepts of density and immiscibility to young students.

MATERIALS

• Clear plastic 0.5 Liter soft drink bottle
• 250 mL of water
• 250 mL of vegetable oil
• Food coloring

WHAT TO DO

1. Fill the bottle halfway full with water.
2. Add a similar volume of vegetable oil.
3. Add the food coloring to the mixture, and then cap the bottle. Students can mix the contents of the bottle together by shaking the bottle. The food coloring will not dissolve in the oil, but will cling to itself until sinking to the bottom of the bottle and dissolving in the water.

QUESTIONS

1. What do you expect to happen when the oil is added to the water?
2. If the vegetable oil were added first, would the liquid on the bottom of the bottle be different?
3. Is there anything that changes the liquid that is on the bottom of the bottle?

SUMMARY

Because the vegetable oil is less dense than water it will float on the water, occupying the top portion of the bottle. The food coloring will only be able to color the water in the bottle, so it clearly shows which layer is the water.

SOURCE

"Teaching Chemistry with Toys Activities for Grades K-9." Jerry L. Sarquis, Mickey Sarquis, John P. Williams, McGraw-Hill, 1995, ISBN: 0-07-064722-4.

Grade Level: This experiment is expected to be appropriate for grades K and above.

© S. Olesik, WOW Project, Ohio State University, 2000.