What is the common name for H2S?

• A. Hydrogen sulfide
• B. Hydrosulfurous acid
• C. Hydrosulfuric acid
• D. Sulfide hydride

Answer: (C)

Naming H2S depends on context. For the neutral molecule, the everyday, common name is hydrogen sulfide, which clearly reflects the two elements and the gaseous form. In water, H2S behaves as an acid, and the solution is called hydrosulfuric acid, not the molecule itself. The systematic name for the molecule can be dihydrogen sulfide, while hydrosulfurous acid points to a different species (sulfurous acid, H2SO3). So the best understanding is that hydrogen sulfide is the common name for the H2S molecule, with hydrosulfuric acid reserved for its acidic aqueous form.