Question

Why doesn’t vegetable oil stay dissolved in vinegar to make a salad dressing?

Answer 1

Vegetable oil is nonpolar, whereas vinegar is polar (about 95% water). Like dissolves like so polar and nonpolar dont mix.

Answer 2

In order for things to dissolve they must dissolve in a solvent similar to them (polar and polar or nonpolar and nonpolar) Oil is nonpolar and vinegar is polar therefore oil wont dissolve in vinegar