Which property would you check for evaluating a chemical’s fire hazard?

When evaluating a chemical's fire hazard, one of the most critical properties to assess is the auto-ignition temperature. This temperature indicates the lowest temperature at which a substance will ignite without an external ignition source, such as a flame or spark. Understanding this temperature is essential for safety assessments, as it informs responders about the conditions under which a chemical could spontaneously ignite.

The auto-ignition temperature provides crucial insight into potential fire risks and helps to establish safe handling and storage protocols. Chemicals with low auto-ignition temperatures pose higher risks in environments where heat buildup might occur, while those with higher temperatures may be less of a concern.

In contrast, specific heat capacity, molecular weight, and viscosity do not directly relate to a material's propensity to catch fire on their own. Specific heat capacity refers to how much heat a substance can absorb before its temperature rises, while molecular weight can influence various chemical properties but does not dictate fire hazards. Viscosity affects flow characteristics but not the ignition potential of a substance. Therefore, the auto-ignition temperature is the most relevant property for assessing fire hazard risks in chemicals.