Acetylene Welding gas; sp-hybridized; weak acid 🧪 Building Blocks PDB source ↓ Drag to rotate · scroll to zoom 3D viewer requires JavaScript. Static renders available below. Structure Formula C2H2 Molecular weight 26.038 g/mol Heavy atoms 2 Total atoms 4 Composition C ×2 H ×2 SMILES C#C ⧉ Copy Class Alkyne