Fluoroantimonic acid (pH −31.3) is a mixture of hydrogen fluoride and antimony pentafluoride, containing various cations and anions (the simplest being  and ). This mixture is a superacid that, in terms of corrosiveness, is trillions of times stronger than pure sulfuric acid when measured by its Hammett acidity function. It even protonates some hydrocarbons to afford pentacoordinate carbocations (carbonium ions). Like its precursor hydrogen fluoride, it attacks glass, but can be stored in containers lined with PTFE (Teflon) or PFA.