Sulfuric acid is the chemical manufactured in the greatest quantity anywhere in the world, and almost all of it is made by the Contact Process. This simulator walks molecules through the plant's three real stages: sulfur is burned with oxygen into SO₂, the SO₂ is driven toward SO₃ over a vanadium pentoxide (V₂O₅) catalyst at a temperature you control, and the SO₃ is absorbed into concentrated sulfuric acid — never directly into water, which would only form an acid mist — to make oleum and, after dilution, commercial-grade H₂SO₄. The catalytic step is a reversible, exothermic equilibrium, so the temperature slider doubles as a live demonstration of Le Chatelier's principle: push it up and the reaction runs faster but the equilibrium yield drops; pull it down and yield climbs while the reaction crawls, the same speed-versus-yield compromise engineers make in the Haber–Bosch ammonia process.