What is the flash point of a substance?

The flash point of a substance is defined as the lowest temperature at which it can vaporize to form an ignitable mixture in air. This is a critical characteristic in understanding the flammability of a material, as it indicates the conditions under which a substance can produce enough vapor to create a mixture capable of igniting when exposed to an ignition source.

Knowing the flash point helps in assessing the hazards associated with handling and storing flammable materials. For example, a substance with a low flash point poses a greater risk in terms of fire safety, particularly in environments where it can be exposed to heat or sparks.

In contrast, spontaneous ignition occurs at a higher temperature than the flash point, while the maximum temperature a substance can reach without igniting and the conditions for an explosion pertain to different parameters of flammability and stability. These concepts are related but distinct and do not define the conditions of flash point, making the chosen answer the most accurate representation of this critical property.