What happens when SO2 is passed through acidified K2Cr2O7 solution?
When SO2 is passed through acidified K2Cr2O7 solution. SO2 gas turns acidified potassium dichromate solution from orange to green reduced chromium +4 to +3.
K2Cr2O7+2H2SO4+3SO2→2Cr2(SO4)3+K2SO4+H2O