I use to fry potatoes reusing the same (olive) oil several times (about 5-6 times), and I salt them while frying. But the the oil doesn’t get salty. What’s the reason for that?
In: 2000
Salt does not dissolve in oil.
Salt is a *polar* molecule because of its ionic bond. Normal sodium has one more electron than it wants and chlorine has one fewer. Unlike with *covalent* bonds, the two do not share an electron. Instead, the sodium atom gives it up and the chlorine atom takes it. This makes the sodium atom slightly positive and the chlorine atom slightly negative. Opposite charges attract, so they stick together like magnets.
Water is also a polar molecule, although water is made with covalent bonds. The way the electrons are shared between the hydrogen and oxygen makes one side a little bit negative and the other a little bit positive. That makes water very good at dissolving other polar molecules. The positive sodium atom sticks to the negative side of one water molecule, and the negative chlorine atom sticks to the positive side of another water molecule, and the water rips the salt apart, carrying the two atoms away.
Oils are nonpolar. The electrons are very evenly distributed so that there is no positive or negative side. That means there’s nothing to grab onto the two atoms in the salt molecule and the salt won’t dissolve.
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