The process whereby a material increases in temperature without drawing heat from its surroundings.

The process whereby a material increases in temperature without drawing heat from its surroundings.

• A. Spontaneous Combustion
• B. Spontaneous Heating
• C. Autoignition
• D. Radiant Heating

Answer: (B)

Self-heating occurs when a material generates heat internally through slow chemical reactions, such as oxidation, causing its temperature to rise without any heat input from the surroundings. This internal heat buildup is the situation described, where the substance warms without external heat sources. If the heat remains trapped, this can continue to the point of ignition, but the process in question is the temperature increase itself, not the ignition event. Radiant heating involves external heat sources transferring energy to the material, so it doesn’t fit. Autoignition would imply the material ignites on its own once it reaches ignition temperature, which is about the ignition event rather than the preceding temperature rise. Spontaneous combustion is the ignition caused by self-heating, again describing what happens after the temperature has already risen and reached ignition conditions. So the best match for a material warming without external heat input is spontaneous heating.

Self-heating occurs when a material generates heat internally through slow chemical reactions, such as oxidation, causing its temperature to rise without any heat input from the surroundings. This internal heat buildup is the situation described, where the substance warms without external heat sources. If the heat remains trapped, this can continue to the point of ignition, but the process in question is the temperature increase itself, not the ignition event.

Radiant heating involves external heat sources transferring energy to the material, so it doesn’t fit. Autoignition would imply the material ignites on its own once it reaches ignition temperature, which is about the ignition event rather than the preceding temperature rise. Spontaneous combustion is the ignition caused by self-heating, again describing what happens after the temperature has already risen and reached ignition conditions. So the best match for a material warming without external heat input is spontaneous heating.