2CoSO4 + H2SO4 + 18H2O + F2 → Co2(SO4)3•18H2O + 2HF
Cobalt(II) sulfate react with sulfuric acid, water and fluorine to produce hydrate cobalt(III) sulfate and hydrogen fluoride. Sulfuric acid - 4М solution. This reaction takes place at a temperature near 0°C.