Calculate the concentrations of S2O8 2-, I-, S2O32 2- in moles per litre of reaction mixture given the following:

Question

20mL of 0.1 M (NH4)2S2O8

added to:
20mL of 0.2M KI
10mL of 0.01M Na2S2O3
5mL 0.2% starch

Also, calculate -(delta)S2O8 2-
that is, how much S2O8 2- is used up (consumed) from the time the above solutions are mixed until a blue colour appears, in moles per litre of reaction mixture.

Answer 1

0.02