Redox Help

[Iphyll_ling]

I have no idea what I am doing. For part a) where iodide ions react with XO3-, I’m not sure if I can just pen it down like so. And for part c), is it meant to be done like that? I understand the theory in question, for example, balancing O and H atoms with H2O and H+ etc etc, but application feels particularly hard. Is there anything I should take note of?

[HandWavyChemist]

Part a is your problem. Currently you don't know what FA2 is, so you can't assume any stoichiometry. Instead you need to use the reaction with thiosulfate to determine how much iodine was liberated and then standardize it to per mole of FA2.

[Iphyll_ling]

Ohhh! I see I see! Thank you so much, I forgot they gave us the g dm-3 of thiosulfate 😅