Which statement about the flash point is true?

Which statement about the flash point is true?

• A. It is the temperature at which a liquid spontaneously ignites
• B. It is the temperature at which a liquid develops enough vapor to form an ignitable mixture with air
• C. It is the temperature at which the liquid boils
• D. It is the temperature at which the liquid becomes a solid

Answer: (B)

The flash point is the lowest temperature at which a liquid can form an ignitable vapor-air mixture near the surface, so that an ignition source can ignite the vapor. At temperatures below this point, there isn’t enough vapor to ignite, even with a spark or flame present. This distinguishes it from spontaneous ignition, which occurs at a higher autoignition temperature without an external flame. It also isn’t the boiling point, which is about a liquid turning into vapor as it reaches its boiling temperature, nor is it about the liquid becoming a solid.

The flash point is the lowest temperature at which a liquid can form an ignitable vapor-air mixture near the surface, so that an ignition source can ignite the vapor. At temperatures below this point, there isn’t enough vapor to ignite, even with a spark or flame present. This distinguishes it from spontaneous ignition, which occurs at a higher autoignition temperature without an external flame. It also isn’t the boiling point, which is about a liquid turning into vapor as it reaches its boiling temperature, nor is it about the liquid becoming a solid.