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How does iron react with sulfur to form iron sulfide?

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combustion — chemical reaction Log burning in a fire. Burning wood is an example of a chemical reaction in which wood in the presence of heat and oxygen is transformed into carbon dioxide, water vapor, and ash.

The reaction between iron and sulfur is a classic example of a synthesis reaction, where two elements combine to form a single new compound, iron sulfide (FeS).1

In this process, one atom of iron reacts with one atom of sulfur to produce one formula unit of iron sulfide. This is represented by the following balanced chemical equation:2

$F e (s) + S (s) \to F e S (s)$

In a laboratory setting, this reaction can be carried out by fusing iron and sulfur together, resulting in brown or black metallic masses. Because matter is conserved during this process, the total mass of the reactants must equal the total mass of the product. For instance, 55.845 grams of iron will react with 32.066 grams of sulfur to yield 87.911 grams of iron sulfide. If the reactants are not provided in this exact stoichiometric ratio, the element that is consumed first acts as the limiting reagent, determining the maximum amount of product that can be formed.32