Salty Stuff: How Salt Melts Ice (Even when it is really, really, really, really, really, really, really, really, really, really, cold outside)

ice cubes

I don’t know about you guys, but it is c-c-c-cold up here in New Jersey! We just had some snow these past couple of days, and, although it looks pretty, it is cold and icy! Everything freezes overnight, so we use a lot of ice to try and keep our ramp from being slippery (ramp to the front of our house- not a skateboard ramp šŸ™‚ ). Since my mom has trouble walking, it is even more important for my family to make sure there isn’t a chance to slip. But, with all this snow, I couldn’t help but wonder: why does salt melt ice, even when it is still freezing outside?

Salt lowers the freezing or melting point of water, so, either way, salt creates a lower melting point! This is common knowledge, but this article restated itĀ so clearly, “Ice forms when theĀ­ temperature of water reaches 32 degrees Fahrenheit (0 degrees Celsius). When you add salt, that temperature drops: A 10-percent saltĀ solution freezes at 20 F (-6 C), and a 20-percent solution freezes at 2 F (-16 C).”Ā Ā This means the salt has to dissolve into the water before it can melt it.

This is so fascinating to you guys, that I just know you’ve tried to watch this happen! If you have actually tried to watch ice melting via salt, the first part that dissolves is the area immediately around the grain of salt. The melting part then spreads, and it is a chain reaction until it is all melted. However, if the temperature is already below 15 degrees F, then the salt won’t do anything, as it can’t melt the ice if there isn’t any water. After all, the solid salt can’t go into the solid ice, right?

Because I know just how hot it is out, you’ll want to understand how to make ice cream! If you want the mixture to freeze, it has to be lower than 32 degrees F. That’s because there is often salt in these mixtures. The salt mixed with ice creates a brine which is lower than 32 degrees F. When the melting point is lowered, the brine is so cold that it freezes the ice cream! So, instead of running over to Dunkin’ Donuts to get that piping hot Iced Hot Chocolate, curl up with a bowl of your favorite, warming ice cream! Enjoy!

Link:
http://science.howstuffworks.com/nature/climate-weather/atmospheric/road-salt.htm

(BTW, my mom is fine, but she had her ankles reconstructed a long time ago. One ankle worked, the other didn’t. So now, it hurts to walk because of that one ankle.)

So ta ta for now and I hope to see your chemical reaction soon!

Advertisements