How does temperature affect vapor pressure and release behavior?

• A. Higher temperature increases vapor pressure, increasing vapor release and hazard potential.
• B. Higher temperature decreases vapor pressure.
• C. Temperature has no effect on vapor release.
• D. Vapor pressure depends only on ambient pressure, not temperature.

Answer: (A)

Raising temperature makes a liquid lose molecules to the vapor phase more readily, so vapor pressure increases. The vapor pressure is the pressure the vapor would exert in equilibrium with the liquid at that temperature. As temperature goes up, more molecules gain enough energy to break free from the liquid’s surface, so the amount of vapor in the air rises and the pressure the vapor would exert increases. This means more vapor can escape into the surroundings, boosting the hazard potential because there is more vapor available for inhalation or ignition, depending on the substance.

The other ideas don’t fit because vapor pressure does change with temperature, not decrease as temperature rises. Temperature clearly affects vapor release, not nothing. And while ambient pressure matters, vapor pressure isn’t governed by it alone; the temperature dependence is the main driver of how much vapor forms and how quickly it releases from the liquid.