Frozen No More
In some parts of the world, people enjoy warm weather all year round. For them, ice is something they get out of their freezer or buy in a bag at the store when they want to put food in a cooler. For folks in other parts of the world, ice is a reality for most of the year (or all of it in some very Northern or Southern latitudes such as Antarctica). In these climates, care must be taken to prevent water from freezing when it could do damage. One critical area of concern is car engines.
News You Can Use
- When water freezes, the three-dimensional arrangement of water molecules changes. In the process, the volume expands as ice is formed. The transient hydrogen bonds connecting individual water molecules become more permanent in ice, giving rise to a more open structure in ice than there was in water. As a result, the ice expands in volume over the liquid water.
- One way to counter this freezing is to introduce another substance that can disrupt those permanent hydrogen bonds. By preventing the formation of the more open ice structure, the freezing point of the mixture is lowered and the water remains in the liquid form at a lower temperature.
- Ethylene glycol (a small organic compound containing two –OH groups) is readily soluble in water. The hydroxyl groups on the ethylene glycol easily form hydrogen bonds with the –OH groups in water molecules. By doing so, fewer permanent hydrogen bonds can form in water, allowing it to remain in the liquid form. All antifreeze solutions contain ethylene glycol as a major ingredient (mixed with water). Some products also contain diethylene glycol (two ethylene glycol molecules connected by an ether linkage.)
- Cars also contain windshield wiper fluid, used to spray on the windshield while driving to clean off dirt and debris. If this material were water, it would freeze solid in cold weather. Many of the products used to clean windshields contain methanol, which is very water-soluble and can form hydrogen bonds with water molecules. This material is very toxic and must be handled with care.
- Watch a video on checking your car antifreeze at the link below:
Show What You Know
Use the links below to learn more about antifreeze. Then answer the following questions.
- Why is water freezing in an engine a serious problem?
- What are characteristics of a good antifreeze?
- What damage to the body is caused by ingesting ethylene glycol?
- What problems are seen when methanol is ingested?
- What keeps some fish in the Antarctic from freezing?