Iron pyrite has which chemical formula?

Iron pyrite has which chemical formula?

• A. FeS
• B. FeS2
• C. Fe2S3
• D. FeS3

Answer: (B)

The formula reflects how many sulfur atoms accompany each iron atom and how those sulfur atoms bond in the mineral. Iron in pyrite forms a disulfide unit, meaning two sulfur atoms are bonded together and together balance the iron. This gives iron disulfide, FeS2. In terms of charges, iron is typically +2, and the disulfide unit carries a total -2, so the charges balance to a neutral compound. That two-to-one sulfur-to-iron ratio is the hallmark of pyrite’s structure, distinguishing it from formulas with only one sulfur per iron or with different sulfur arrangements.

The formula reflects how many sulfur atoms accompany each iron atom and how those sulfur atoms bond in the mineral. Iron in pyrite forms a disulfide unit, meaning two sulfur atoms are bonded together and together balance the iron. This gives iron disulfide, FeS2. In terms of charges, iron is typically +2, and the disulfide unit carries a total -2, so the charges balance to a neutral compound. That two-to-one sulfur-to-iron ratio is the hallmark of pyrite’s structure, distinguishing it from formulas with only one sulfur per iron or with different sulfur arrangements.