Question

Why does salt dissolve in water but not oil?

Answer 1

Positive and negative charges on water molecules are attracted to sodium and chloride ions as seen in the image above. Water molecules “hydrate” sodium and chloride ions, keeping them separate in water, which, when you think about it, is quite extra-ordinary. And preventing salt’s ions from re-combining is something that water is particularly good at because it forms this protective sheath around the ions. All the more interesting is that while water can keep salt ions separated, even at room temperature, oil cannot. What are the differences between water and oil? Water and oil have many differences; here, we will focus on their very different dielectric constants. Water has a dielectric constant
of 80, while oil has a dielectric constant of only 2.
for more reading http://physicsindrops.tumblr.com/post/60842799964/why-does-salt-dissolve-in-water-and-not