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Learn about the unique chemsitry of water through this lesson.
Get this lesson: You can download the full packet here or read a condensed version of this unit below.
Worksheet: Download just the worksheet or there’s a copy included in the packet.
Overview:
Water covers 71% of Earth’s surface and is unique because it exists in all three states: solid, liquid, and gas. Below freezing at 32 degrees F it is a solid, and above the boiling point (212 degrees F) it is a gas. Water molecules are composed of one oxygen atom and two hydrogen atoms, giving it the chemical symbol H20. Water is a “polar molecule” meaning there is an uneven distribution of electron density. The ability of ions and other molecules to dissolve in water is due to polarity. Because of this, water is referred to as the “universal solvent”.
The hydrologic cycle describes how water is transferred over the Earth, and also explains how human impacts on one part of the water cycle can affect more than just the surrounding area.
Because of water’s solvent properties, it can dissolve elements like nitrogen and phosphorous, which enter waterways through farm runoff containing fertilizer. This can create many harmful effects on humans and organisms.
Video resources:
The Chemistry of Water – An easily digestible chemistry lesson with visual diagrams explaining the chemical makeup of water and what makes it unique.
Great Lakes Now: The Algae Crisis – A detailed video on issues caused by farming leaking phosphorous into the nearby Great Lakes.
What is Nitrogen Pollution – An animated visual diagram explaining how Nitrogen impacts waterways
Sample Research Project:
Studying pH and alkalinity for rivers – find a nearby waterway and test for pH and alkalinity in samples you collect. This project from the Massachusetts Water Watch Partnership contains methods and a materials list to complete the experiment.
Sample Research Questions:
- Is water near civilization in an urban stream more acidic or more basic than water in a rural stream?
- How do pH and alkalinity correlate?
- Are there more species living in acidic or basic water?
- Are there more species living in more or less alkaline water?
NGSS Standards:
HS-ESS3-6: Earth and Human Activity
SEPs: Analyzing and interpreting data
Constructing Explanations and designing solutions
Engaging in argument from evidence
Planning and carrying out investigations
Asking Questions
CC: Cause and effect
Stability and change
Patterns
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