[MissDee]

C₆H₈O₆ + I₃^- + H₂O   C₆H₆O₆ + 3I^- + 2H⁺

Does this mean that the moles of I2 added is equal to the moles of ascorbic acid in the sample? Ie, is it a 1:1 ratio? Then what is the significance of the 3 moles of I₂ formed as a product?

[Fluorine]

There is no iodine (I₂) on either side of the chemical reaction you supplied. I₃^- is triiodide ion and I^- is iodide ion.

According to the reaction 1mol ascorbic acid, 1mol triiodide ion, and 1mol water will form 1mol dehydroascorbic acid, 3mol iodide ion, and 2mol protons/hydrogen ion. Yes triiodide and ascorbic acid are 1:1, the 3mols I^- is because the triiodide is split up during the reaction.

Hope this helps.