K2Cr2O7 + 3K2S + 7H2O → 2K3[Cr(OH)6] + 3S + 2KOH
Potassium dichromate react with potassium and sulfide water to produce potassium hexahydroxochromate(III), sulfur and potassium hydroxide. The reaction takes place in a concentrated solution potassium hydroxide.