There are many common applications of colligative properties. Choose a topic related to colligative properties that you’d like to research and share with the class. Some ideas are presented below, but as always, you can choose your own topic.
Vapor pressure lowering
Alcoholic beverages can be made through fermentation. For example, wine is made by fermenting grapes. The fermentation process is carried out by yeast. The resulting solution is mainly ethanol (ethyl alcohol) and water. To make liquors with a higher alcohol content, like brandy, distillation is used. Discuss why high alcohol content cannot be achieved by fermentation alone. Use the concept of vapor pressure lowering (and probably Raoult’s Law) to explain how distillation can be used to enrich the alcohol in liquors. If you do not want to promote alcoholic beverages, you can frame the discussion in the context of ethanol’s use as a gasoline additive or in hand sanitizer.
Freezing point depression and boiling point elevation
What is the antifreeze/coolant that you put in your car? How does the substance function as both an antifreezing agent and a coolant?
Have you ever made ice cream at home? Some of the simpler ice cream makers call for ice and salt to freeze the cream, sugar, and other ingredients. You can even find very simple examples on the internet where you make ice cream using plastic bags. How do colligative properties apply to these types of ice cream makers?
Have you ever been on a plane that had to be de-iced before take-off? What are some de-icing agents and how do they work?
Have you ever been in a city where it snowed? If snow is frequent enough, a city will often have equipment for spreading salt along the roads. Which salts are commonly used for salting roads and how do they make the roads safer for driving?
Osmotic pressure
How does osmotic pressure affect biological cells? What are some ways that biological cells deal with osmotic pressure extremes? What happens if cells don’t deal with osmotic extremes well?
California experiences periodic drought, but the state boarders the ocean. Why can’t we just get the water from the ocean? You might want to look up desalination and reverse osmosis, in particular.
If you find yourself in a survival situation, why is it a bad idea to drink sea water?
Sample Solution
