Many of my patients called in today to cancel their PT appointments because of our big bad winter nemesis ICE! I’ve overhead a lot of people talking about “salt melting ice” and had a flashback to chemistry and got WAY to excited. After setting nerd-phasers to stun, boring all my colleagues (trapped in a small office they had no choice but to indulge my silly tangents) I decided to share with you. So, if you are up for a mini chemistry lesson read on!
Technically, salt doesn’t melt ice, it lowers the freezing point of water. We all know that ice forms when the temp of the water is 0° Celsius (32°F). When you add salt, that temperature drops, so a 10% salt solution freezes at -6° C (20° F) …add more salt to the solution: a 20% salt solution freezes at -16° C (2° F).
So, sprinkling some salt on an icy road dissolves into the liquid water in the ice and lowers the freezing point slowly spreading out as more ice becomes water. If you live in a cooler climate you’ve probably seen this happen, the ice immediately around the grain of salt melts, and then spreads out from that point. (RESISTANCE IS FUTILE hard water!)
Well, turns out not completely futile. If the temp of the roadway is TOO cold [normally lower than -9° C (15° F)] salt really won’t have an effect because there is no liquid water to start the dissolving process.
Luckily for us Baltimorians we’ve got plenty of slushy water on our roads to get that ice a-melting. However, I don’t want to see any of you in my office after a bad slip! So if you can, I recommend staying inside with hot coco in your jammies and reading by the fire!
And if you made it this far, you deserve a little chemistry joke:
16 Sodium Atoms walk into a bar, followed by Batman.