Can you really dissolve ice with table salt?

[dstebbins]

I understand that, from a scientific perspective, there is more than one kind of salt. The salt that we typically use as a seasoning on our food is called sodium chloride, aka table salt.

 

My car is currently stuck in ice in a restaurant parking lot. I live within walking distance of this restaurant (and, as a direct result, I'm a regular customer there), but the walk (as opposed to the drive) is still F'ing brutal!

 

I can't go forward, because that giant stone slab is in the way, and I can't back up because there's too much ice. I don't wanna pay out the ass for a towing service.

 

My neighbor just told me that, in the morning, I can just sprinkle some salt onto the ice, and it will dissolve the ice enough for me to get out of there, but I didn't question him as to whether he actually did it himself, or just heard about it happening, before. See, the city will actually use some kind of salt to dissolve the ice on the streets, but I don't know if the city actually uses sodium chloride.

 

Is this even theoretically possible? Can you really dissolve ice with sodium chloride? I don't have any table salt with me, so I can't just make some ice cubes and find out in my own qsuedo-lab (but, then again, that would probably be a totally different environment, right there), so I have no choice but to ask you guys.

[Moontanman]

I understand that, from a scientific perspective, there is more than one kind of salt. The salt that we typically use as a seasoning on our food is called sodium chloride, aka table salt.

 

My car is currently stuck in ice in a restaurant parking lot. I live within walking distance of this restaurant (and, as a direct result, I'm a regular customer there), but the walk (as opposed to the drive) is still F'ing brutal!

 

I can't go forward, because that giant stone slab is in the way, and I can't back up because there's too much ice. I don't wanna pay out the ass for a towing service.

 

My neighbor just told me that, in the morning, I can just sprinkle some salt onto the ice, and it will dissolve the ice enough for me to get out of there, but I didn't question him as to whether he actually did it himself, or just heard about it happening, before. See, the city will actually use some kind of salt to dissolve the ice on the streets, but I don't know if the city actually uses sodium chloride.

 

Is this even theoretically possible? Can you really dissolve ice with sodium chloride? I don't have any table salt with me, so I can't just make some ice cubes and find out in my own qsuedo-lab (but, then again, that would probably be a totally different environment, right there), so I have no choice but to ask you guys.

 

 

Yes, common table salt will indeed melt ice. Most cities use coarse salt granules 1/4 inch or so, often literal mountains of it to keep the roads clear. To melt out your car will take several pounds of salt at least, I would want 25# or so... Oh yeah, if it's cold enough, the salt will not melt the ice....

Edited February 3, 2011 by Moontanman

[Mr Skeptic]

Salt can only melt ice at temperatures above about 0 Fahrenheit. (in fact, that was how Mr Fahrenheit got his zero temperature). Anything that dissolves in water will melt ice to some extent, but salt is so effective because so much of it can be dissolved and because both the sodium and the chlorine count for this, and more importantly because it is cheap.

 

Like Moontanman said, don't go there with a salt shaker and expect to do anything. Shoveling the snow out will be quicker, at least if the snow is soft enough. Otherwise, a large bag of salt will eventually melt the snow and ice. The way it works is that salt water freezes at a lower temperature than fresh water, and basically the salt dissolves in the water formed by the melting ice, but the process is rather slow since the salt needs to dissolve in ice water and melting ice requires heat such that the temperature is lowered as it melts, and it has to warm up from the surrounding environment. But it will eventually melt it, and also it will make little holes and stuff in the ice which will make it less slippery.

[swansont]

Salt will work slightly below freezing, since there's some small amount of liquid present to dissolve the salt. The mechanism is freezing point depression, so what you're doing is melting the ice below the freezing point of pure water. Of course, as the ice melts, the salt gets diluted and the effect diminishes. Hence the need for more salt.

 

 

You can also try a few jugs of hot water.

[Sisyphus]

They do often use NaCl on the roads, so it will certainly work. The other salt they use is CaCl2, which works faster and at lower temperatures and is less environmentally damaging, but is also somewhat more expensive and can be slippery itself.

 

I wouldn't use salt to melt a big pile of snow, though, just because you would need a lot. Better to shovel, then use salt, so the last bits melt and traction improves. There's a reason they plow the roads and then salt them.

[Doc. Josh]

Shovel the snow when its fresh, then sprinkle salt on the driveway after it will ice up alot less than without.

[kristina221]

why not just heat up a teapot full of water , throw it on the ice and move your car before it freezes again?

[CaptainPanic]

Even cold water can melt the ice/snow. however, you will need a place it can run off to, otherwise you just create a skating ring in the parking lot. This disadvantage also goes for the hot water: it's gonna turn to ice eventually.

 

As a rough guideline, 1 liter of boiling hot water can melt 1 kg of ice. 1 liter of cold water (10 Celsius) will only melt about 100 grams of ice... so you need lots of water.

 

Salt is an option, but as was said before: you need lots of salt, and it is not guaranteed to work (depends on the temperature).

 

I would recommend just shoveling it out...

[Mr Skeptic]

So, any luck getting your car out?