What kind of compound is table salt and how does it dissolve in water? Would salt dissolve in vegetable oil? Why or Why not?

Answer 1

Table salt is NaCl, an ionic compound. It dissolves in water due to the dipoles of H2O attracting the positive Na ions and the negative Cl ions. That plus the energy released when the Na ion and Cl ion form hydrates with the water is enough to break the lattice energy of the NaCl crystal. NaCl will not dissolve in vegetable oil because vegetable oil is not polar (as water is). There's an old saying that "like dissolves like" meaning that polar compounds dissolve in polar solvents and non-polar compounds dissolve in non-polar solvents. Thus NaCl dissolves in water but not in vegetable oil; the dirty oil on an old rag will dissolve in vegatable oil but not in water.