What's in Iowa's Anti-Ice Road Spray?

In this video, a West Des Moines Public Services staff member explains their anti-ice spray and mixing system.

• Why are brine, calcium chloride, and carbohydrates used in de-icing road spray?

• What are the environmental impacts of these chemicals?
• Does the ratio of these three components in the solution influence West Des Moines Public Service’s costs and efficacy?

Students could:

• Investigate each component of the solution, including their physical and chemical properties, and have them use this information to evaluate an ideal mix of the solution for its intended purpose.
• Conduct an inquiry lab where students investigate how each component of the solution affects ice formation? If done in winter, students can collect samples from sidewalks or cement. If done in warmer weather, samples can be set up in ice trays.
• Conduct an inquiry lab where students investigate if the percentage of each component in the solution impacts its ability to prevent ice or be removed by snowplows. Similarly have students custom mixing components instead of using one at a time.
• Conduct an inquiry lab where students perform an LC50 (daphnia) for each component of the solution and then make recommendations. (Daphnia would be better than brine shrimp in this case because of their inherent resistance to brine solutions).

• How Stuff Works | Why is Salt Used to Melt Ice on the Roads in Winter: This website provides a basic description of using salt as a road anti-ice component.
• Scientific American | Salt Doesn’t Melt Ice—Here’s How It Makes Winter Streets Safer: A great resource on freezing point depression and how it relates to winter road management.