oh snap, i forgot to write my weekly article about something or other.
So here’s the most important science thing you’ve never known why.
ADDING SALT TO WATER
So people add salt to water on three occasions for three different reasons.
adding salt to ice
So sometimes we add salt to ice when we’re making ice cream or chilling a bottle of champagne. The reason is pretty high-school chemistry.
Ice (unless it’s super cold) always has some liquid water (and then a layer of slush) on its surface. The molecules are always in the process of breaking off from the big ice crystal; and re-attaching themselves to the ice crystal. If you add salt to it, the salt will dissolve in the water; and the ions will prevent the water from forming into a nice crystal lattice. So the ice melts, and doesn’t turn back into ice; EVEN THOUGH it stays at the same temperature.
This is handy when you don’t want to slip and fall in the winter; and it’s also handy when you want to use ice to cool a bottle of wine. heat exchange is a matter of surface area. The more surface area is touching, the faster the heat will flow. So if you immerse a bottle in a pile of ice cubes and compare the surface area of the ice touching the bottle, with a bottle immersed in a icey slush. the slush bottle will cool faster.
Adding Salt to boiling water to cook an egg
this is fun. folk wisdom tells us to add salt to boiling water when we want to boil an egg.
why the hell do we add salt? people who know how salt DECREASES the freezing temperature of water suggest that adding salt will increase the boiling temperature of water. So that the water will boil at 110 degrees Celcius, instead of 100 C. This is nonsense.
the answer is kind of coolllll.
what happens is, you know how sometimes, in the boiling violence of the water; the eggs get cracked? and then you get long elephant trunks of cooked egg-white sticking out of the shell? you know how that sucks?
adding salt to the water keeps that from happening.
i don’t know how it works? maybe the salt increases the heat capacity of the water? *shrug* maybe it’s magic.