What is a primary factor that creates a reactivity hazard?

Water-reactive chemicals are a primary factor that creates a reactivity hazard because they can undergo vigorous reactions upon contact with water. This type of reactivity can lead to the release of flammable gases, heat, or even explosion in some cases. For instance, substances like sodium and potassium can react violently with water, producing hydrogen gas and causing dangerous situations.

In contrast, while certain metals can exhibit reactivity, it is typically in specific conditions that do not inherently involve a water-reaction hazard. Sugar-based compounds and food additives generally do not present significant reactivity hazards when considering standard environmental conditions; they are primarily considered safe for use in food and other applications. Therefore, the presence of water-reactive chemicals stands out as a clear and critical concern when assessing reactivity hazards.