SAChE Chemical Reactivity Hazards (ELA962) Practice Test

Reactivity hazards arise when incompatible chemicals come into contact and react, potentially releasing heat, gas, or pressure. Accidental mixing of incompatible substances is the scenario most likely to trigger such a hazard because it creates the first opportunity for a violent or uncontrolled chemical reaction. When substances that shouldn’t react with each other do mix, the resulting reaction can escalate quickly, leading to overheating, gas buildup, pressure rise, fire, or even an explosion. That risk is inherent to the reaction itself, not to a safety measure being applied. The other scenarios describe safety practices that reduce or prevent hazards. Storing chemicals properly and venting helps prevent build-up of dangerous vapors and moisture-related issues. Using an inert atmosphere with appropriate controls stops reactions with air or moisture. Maintaining proper temperature and pressure reduces the chance of a runaway reaction. None of these, by themselves, describe an immediate hazard—rather, they are ways to keep hazards from occurring.