[belyzel4]

Hey there guys! I am having a great deal of trouble with this problem and I am not exactly sure what to do.
How do I figure out the concentration of Thiosulfate in mol/L or g/L if I am only given the following:

0.00167M Iodate (IO3-)
10g of 0.00167M Iodate (IO3-) in Solution
0.78g of Thiosulfate necessary to titrate
IO3- MW = 174.9027 g/mol
Thiosulfate MW = 248.18 g/mol

I have been resorting to assuming 1g ~ 1mL even though I know for a fact that is not the case here. It is the only way I can seem to plug in the 10g IO3- or 0.78g Thiosulfate.... I am so confused!

[belyzel4]

I think the general reaction might help:
IO3- + 8I- + 6H+ -----> 3I3- + 3H2O
I3- + 2S2O3 -----> 3I- + S4O6

[Borek]

I agree it is pretty confusing, but - apart from using density tables - I can't think of a better approach.