How many milliliters of 0.200 M FeCl3 are needed to react with an excess of Na2S to produce 0.690 g of Fe2S3 if the percent yield for the reaction is 65.0 3 Na2S(aq) plus 2 FeCl3(aq) Fe2S3(s) plus?

To find the moles of Fe2S3 produced, convert 0.690 g to moles using the molar mass of Fe2S3. Then, use the stoichiometry of the reaction to determine the moles of FeCl3 required. Finally, use the molarity of FeCl3 to calculate the volume in milliliters needed, keeping in mind the percent yield.