Video: Thiosulfate ion as a reducing agent
Thiosulfate reduces brown iodine solution to colorless iodide ion, itself being oxidized to the tetrathionate ion.
2 S
2
O
3
2-
(aq) ® S
4
O
6
2-
(aq) + 2 e
-
I
2
(aq) + 2 e
-
® 2 I
-
(aq)