The reason our palm feels cold when we put acetone, petrol, or perfume on it is due to evaporation. These substances are volatile, meaning they evaporate easily at room temperature. When applied to the skin, they rapidly change from liquid to vapor by absorbing heat from the palm. This absorption of heat (latent heat of vaporization) cools down the skin, leading to a cold sensation on the palm.
Explanation
- Acetone, petrol, and perfume evaporate quickly because of their low boiling points and high volatility.
- The evaporation process requires energy, which is taken as heat from the skin.
- This heat absorption lowers the temperature of the skin surface, causing the palm to feel cold.
This cooling effect is an example of an endothermic process where the evaporation draws heat from the surroundings (in this case, the palm), resulting in the sensation of coldness.
