How to Make Water Float on Water for a Science Project

Water is so versatile, it can be used in many different experiments.

Water is an important substance. It covers 70% of the world's surface, and is vital for human and mammal survival. When water has solidified into ice, it can easily float on itself, but a science project on whether water in liquid form can float on itself is a both impressive and simple experiment. The experiment takes less than a day to carry out, and involves many scientific concepts, such as density and salinity.

Things You'll Need

• Pen
• 6 Labels
• 4 clear plastic water bottles
• Tap water
• 2 small plastic containers
• Salt
• 2 food colorings in different colors
• Small piece of thin plastic, such as plastic business card
• Notebook

Instructions

1. Write "Salt" on three labels, and "Fresh" on the other three.

2. Label two bottles and one container with the "Salt" labels, and two bottles and one container with the "Fresh" label.

3. Fill each container with 300ml of tap water.

4. Add salt to the "Salt" container. The amount of salt you add is up to you, but ensure you record how much you add.

5. Stir the salt container until the salt has fully dissolved in the water.

6. Add three drops of food coloring to the salt container. Mix until the water changes color.

7. Add three drops of the other food coloring to the fresh container. Ensure this is a different color, so you can tell the difference between the solutions.

8. Write down the color of each solution in your notebook.

9. Fill one "Salt" bottle with the salt solution.

10. Fill one "Fresh" bottle with the fresh solution.

11. Place the plastic business card over the top of the salt bottle.

12. Place the fresh bottle in front of you, so you can easily place the salt bottle on top. Ensure you will not knock the bottle over when you move.

13. Hold the salt bottle at the bottom. Avoid squeezing the bottle. Use your other hand to hold the plastic business card in place.

14. Turn the salt bottle upside down, keeping your fingers in place over the business card.

15. Balance the salt bottle on top of the fresh bottle, with the plastic card separating them.

16. Pull the plastic card out from between the bottles, while holding the bottles as steadily as possible. You may have some minimal spillage if the bottles move.

17. Observe what happens in the solution. Write down what happens in your notebook. Remember which color solution is which.

18. Repeat the experiment with the other bottles, but this time turn the fresh water into the salt water. Observe if the results change.

Tips & Warnings

• Use food colorings which very contrasting colours. Choosing strong, contrasting colors makes identifying each solution much easier.

• To extend the experiment, try repeating it with different amounts of salt.

References

• "Experiments with Water: Water and Buoyancy"; Chris Oxlade; 2010
• "The Everything Kids' Science Experiments Book: Boil Ice, Float Water, Measure Gravity- Challenge the World Around You!"; Tom Mark Robinson; 2002