The weather forecast for the morning is a mix of freezing rain and snow and meteorologists are telling drivers to be careful, that roads will be icy and slippery. Is there any way to make the roads safer? Yes, trucks will be out spreading salt on the roads, but how does this help?
Salt lowers the freezing point of water. As salt dissolves in water, it releases ions (an atom that has a positive or negative charge). The ions make it harder for water molecules to bond and form ice. The freezing point of fresh water is 32°F. The freezing point of a 10 percent saltwater solution (a mix of two or more substances that are evenly mixed) is 20°F. The more salt added, the lower the freezing point goes, with the saltiest water freezing at about -6°F.
Cities and towns have been spreading salt on roads for decades. It works, but it can have negative impacts. Salt can corrode (to wear away slowly) cars, roads, and bridges. It also enters ecosystems, (all the living and nonliving things in an area) and extra salt in ecosystems can harm plants and animals. The salt also eventually reaches groundwater (water that is below Earth’s surface) which some people use as drinking water.
What can be used in place of salt? One answer is pavement that allows water to soak into it. The water does not collect and freeze on top of it, reducing the need for salt. Some cities use a mix of salt and sand. The sand helps cars stop faster, so less salt is needed.
Some towns are mixing sugar beet juice with a salt solution. The sugar beet juice helps the salt solution stick to the ground better. It does not corrode things as much as salt does, and it costs about the same as the salt solution.
Some cities take advantage of technology to reduce the amount of salt they are spreading while still ensuring safety. The trucks have computers that allow drivers to adjust the amount of salt they are applying and track what other trucks in the area are doing.
What Do You Think? What does your town do when roads are icy or slippery?
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