3H2S + 2K2CrO4 + 2H2O = 3S + 4KOH + 2Cr(OH)3, S-2 -2e- = S (3), Cr+6 +3e- = Cr+3 (2).
H2S+K2CrO4+H20=S+2KOH+Cr(OH)3 Н+1,S-2. + K+1Cr+6O-8 + H+1O-2= S-0 + K+1O-2H+1 + Cr+3O-2H+1