Autoignition temperature is defined as the minimum temperature at which a substance does what?

Autoignition temperature is defined as the minimum temperature at which a substance does what?

• A. Ignites with an external flame
• B. Ignites without an external ignition source
• C. Reaches the vapor-liquid equilibrium
• D. Flashes when exposed to air

Answer: (B)

Autoignition temperature is the minimum temperature at which a substance will ignite in air without an external ignition source. When heated to this temperature, the rate of oxidation becomes fast enough that the heat released sustains combustion on its own, without a flame or spark. This concept is key for safety, since materials can ignite just by sitting on a hot surface or in hot air if the temperature is high enough. It’s different from the flash point, which is the lowest temperature at which vapors can ignite in air only if an ignition source is present. It also isn’t about reaching vapor-liquid equilibrium, which is a phase behavior idea rather than a combustion one.

Autoignition temperature is the minimum temperature at which a substance will ignite in air without an external ignition source. When heated to this temperature, the rate of oxidation becomes fast enough that the heat released sustains combustion on its own, without a flame or spark. This concept is key for safety, since materials can ignite just by sitting on a hot surface or in hot air if the temperature is high enough. It’s different from the flash point, which is the lowest temperature at which vapors can ignite in air only if an ignition source is present. It also isn’t about reaching vapor-liquid equilibrium, which is a phase behavior idea rather than a combustion one.