Spilling room-temperature water over your skin on a hot day will cool you down. Spilling vegetable oil (of the same temperature as the water) over your skin on a hot day will not. Explain the difference.

Explanation:

Spilling room temperature water over your skin on a hot day will cook the body down. This is because water has a low heat of vapourization( water can evaporate into gas molecules easily). This evaporation causes a cooling effect on the skin surface and it requires heat energy as liquid is converted to gas. This is a typical example of an endothermic process. BUT spilling vegetable oil of the same temperature as the water over the skin will not cool the body down because oil has a high heat of vapourization and doesn't evaporate because it is a viscous liquid and the molecules are tightly bound to each other. I hope this helps.