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Activity (Hands-On)Grades 9 - 11

Balancing Liquid on a Coin: How Intermolecular Forces Work

What can the act of balancing liquid on the surface of a coin tell us about the water molecules and molecular formulas? In this activity, students observe different types of intermolecular forces of water through two simple experiments. During this introductory activity students have hands-on experience visualizing the effects of hydrogen bonding through surface tension and evaporation.

A paper towel with a penny on top of it and two drops of water on the penny that have come from a dropper above. There is a small glass of water in the top right of the image.Experiment #1 Set-Up

Wastewater engineers work to ensure that all water systems at a water treatment plant are working correctly. Their responsibilities revolve around producing clean, safe drinking water for the community. Their duties include the design and operation of the machines, systems, and equipment that receive, clean, and distribute water. Knowing the basic properties of water is an important first step in developing water treatment methods.

After this activity, students should be able to:

  • Explain why water is important to life.
  • Explain how the properties of water and isopropyl alcohol differ due to their molecular structures.
  • Consider how the properties of water make it unique and why it has a higher evaporation point than alcohol.
  • Have a cursory knowledge of water’s structure to consider its properties for future engineering.

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