Dumping massive amounts of salt onto roads to prevent the streets from icing over is the stereotypical example of colligative properties in action, seen here as freezing point depression. According to Mayor Madeline Rogero’s tweet on Tuesday, 1,430 tons of salt were dumped on the streets of Knoxville in just two days this week.
What’s the science behind salty but ice-free roads, you ask? My younger sister asked the same question when I was a sophomore in high school, right in the midst of my first chemistry class, and my mom groaned in anticipation of my dissertation-length answer. It really is quite simple, though. Adding salt to a solution of water and whatever road grime is swilling around on the streets introduces more chemically charged ions to the wintry cocktail. The water and dissolved salt are buzzing around with way too much excitement to enter a slow-moving, orderly arrangement of fixed crystals like ice. Temperatures must drop well below pure water’s freezing point to get that liquid party to chill out.
Armed with this rather useful chemical property, UT Facilities Services employees began spreading ice all across the streets and sidewalks of campus Sunday night. Nature one-upped this maneuver as the sheer volume of water and the particularly frigid temperatures dropped nearly an inch of ice across Knoxville. Tuesday saw another victory for Mother Nature, but stubborn UT spread more salt still and sent its students and faculty members slipping and sliding to class on Wednesday.
I strapped on my Yaktrax (last used to traverse a glacier in Iceland) and walked 45 minutes from South Knoxville to class. I lost count of the number of people I saw lose battles to failed traction and gravity on the ice-covered sidewalks. I felt guilty for tracking slush, ice, salt and grime into the building as the custodians pushed mops across the perpetually dirty floors.
What happened there, UT? Somebody missed a step in an otherwise very simple thought experiment. “The main roads are clear, but the secondary roads most certainly are not. Students could still walk to campus though, right? And we most certainly salted every last crack of those sidewalks. Classes must go on!” Wrong. Students cannot walk to campus on sheets of ice, and spreading salt on top of this smooth, frozen surface didn’t make a bit of difference when air temperatures sat stubbornly in the teens and single digits.
Yet as I sat watching the snow drip from my hiking boots, clasping a steaming mug of tea, I decided that lessons could be learned from trekking to school on sheets of ice sprinkled with a smidgen of salt. There’s a limit to colligative properties, and there’s a limit to being stubborn in all aspects of life. Just like a weather forecast, we do have some insight into our futures. When there’s already ice on the ground and the weather will continue to be damn cold, save yourself the salt and sweat. If you know with certainty the battle’s outcome has already been decided, save yourself the anguish of investing in a guaranteed loss. Fight bravely until you reach that point of inevitability, and then listen to your gut. Bow out. Cut your losses, and count what’s not lost as a blessing. Ignoring facts you already know is no longer ignorance, but stupidity. Avoid such behavior at all costs.
Kenna Rewcastle is a senior in College Scholars. She can be reached at [email protected].
