How would we represent the reaction of #SO_2# with #K_2Cr_2O_7# to give #SO_3#?

1 Answer
May 6, 2017

Answer:

We would assume that the sulfur dioxide is oxidized to sulfur trioxide.

Explanation:

#stackrel(IV+)"SO"_2 +H_2O rarr stackrel(VI+)"SO"_3 +2H^(+) +2e^(-)# #(1)#

And dichromate is reduced to chromic ion......:

#Cr_2O_7^(2-) +14H^(+) + 6e^(-) rarr 2Cr^(3+) + 7H_2O# #(2)#

And we take #3xx(1)+(2)# to eliminate the electrons:

#Cr_2O_7^(2-) +8H^(+) + 3SO_2 rarr 2Cr^(3+) + 3SO_3 + 4H_2O#

Are charge and mass balanced? If the answer is no then we cannot accept the reaction. Industrially, the oxidant is oxygen gas. I do not know if the reaction would proceed as written.