Bassam Z. Shakhashiri: Chemical demonstrations: a handbook for teachers of chemistry, Volume 5

Abstract

This reaction is initiated by heat (burning Mg) and becomes self-sustaining. The reaction generates oxygen and therefore combustion occurs even in the absence of oxygen. The reaction creates so much heat that the iron generated is melted. The melting point of iron is 1530 o C and has ∆H fus = 14.9 kJ/mol. The overall free energy change (∆G) of this reaction at 298 K is-838 kJ/mol (Shakhashiri, 85). Safety: DEMONSTRATORS MUST PRACTICE THIS DEMONSTRATION PRIOR TO PERFORMING THIS DEMONSTRATION IN CLASS. Do not look directly at the burning magnesium fuse. This reaction produces intense heat and molten metal. A fire extinguisher should be readily available. Water should never be used to extinguish this reaction as hydrogen gas, which is explosive, may be produced. A safety shield is necessary to protect from sparks. Heat protective gloves should be worn to handle the molten iron. Disposal: Once materials are cooled they can be disposed of in a solid waste container.