Here's why:
* Sublimation: This is the process where a solid directly transitions into a gas, skipping the liquid phase. Benzoic acid has a relatively high vapor pressure, meaning it readily vaporizes at temperatures below its boiling point.
* Melting Point: Benzoic acid's melting point is around 122 degrees Celsius. At 140 degrees Celsius, it will be well above its melting point, and in the liquid state.
* Boiling Point: Benzoic acid's boiling point is 249 degrees Celsius. At 140 degrees Celsius, it's still significantly below its boiling point.
Therefore, at 140 degrees Celsius, the solid benzoic acid will melt and then begin to sublimate. You would likely observe a white vapor forming above the heated sample.
Important Note: While sublimation is the primary outcome, there is a possibility of some decomposition occurring at this temperature, especially if the heating is prolonged. This decomposition could lead to the formation of other products, but it is less likely than sublimation.
