[Joules23]

Did i do part (a) and part (b) correctly? ..

and im not sure how to do part (c), since both Fe and Cl are the limiting ions, will they both be used up all the way? so i just have a remainder of Na and CO3 ions left?

[GoldShadow]

Part (a) is done correctly.

For part (b), you only need to say that Fe is the limiting reactant, because the question asks which ion limits the amount of precipitate formed (in other words, FeCO₃.

For part c, NaCl is soluble, so you don't need to worry about limiting reactants and what not.  The ions left in solution after the iron carbonate precipitates out are 3mmol of CO₃^2-, 90mmol Na⁺ and 84mmol Cl^-.  Recalculate their molarities based on the new volume (120 mL).

[Borek]

Part (a) is done correctly.

Nope. mL -> mmoles, not moles.

Joules23: write net ionic reaction to see why Fe²⁺ is the limiting reactant.

You may check your calculations using EBAS. Red means too much