H2S+ZnO=H2O+ZnS ZnS+2HCL=ZnCL2+H2S H2S+2KOH=K2S+2H2O 2H2S+3O2=2S+2H2O S+O2=SO2 SO2+2KOH=K2SO3+H2O K2SO3+Ca(OH)2=CaSO3+2KOH