Ammonium metavanadate reacts with sulfur dioxide in acidic solution as follows (hydrogen ions and H2O omitted):

Question

xVO3^–^ + ySO2 → xVO^2+^ + ySO4^2–^
What is the ratio of x : y?
A. 1 : 1
B. 1 : 2
C. 2 : 1
D. 1 : 3
E. 3 : 1

Answer 1

x = 2
y = 1
How did I do that?
V on the left has a oxidation state of +5 and on the right it is +4.
S on the left is +4 and on the right is +6.
V has changed by 1e
S has changed by 2e
So V couple must be multiplied by 2 and S couple by 1 to make each lose/gain 2 electrons.

Answer 2

thank you!!