I'm not really sure how to do this. I've tried many ways and I can't get the right answer of 0.0569 mol/L H3PO4

Question

100.0 mL of a solution containing 2.55g of potassium hydroxide is mixed with 100.0 mL of a 1.50 mol/L phosphoric acid solution. Will the resulting mixture be acidic or basic? What will be the molarity of the potassium phosphate formed? (Assume the volumes are additive).
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My work:
3KOH + H3PO4 --> K3PO4 + 3 H2O

I found moles of K3PO4 by taking mass of KOH 2.55 g and dividing it by molar mass 56.11 g/mol, multiplying by mol ratio of 1 mol of K3PO4 over 3 mol of KOH. I got 0.0151488148 mol K3PO4

I found moles of K3PO4 by taking volume of H3PO4 0.1000 L and multiplying it by the concentration 1.50 mol/L, then multiplying by mol ratio of 1 mol K3PO4 over 1 mol of H3PO4. I got 0.015 mol K3PO4.

Now I have to find limiting reagent? But aren't they the same mol? Not sure what to do next. Please help

Answer 1

I don't see anything wrong with what you've done and I don't consider the two answers the same. To three significant figures 0.0151 vs 0.0150 so all of the H3PO4 (the limiting reagemt) is used and a slight excess of KOH is present. Note that the problem asks for M of K3PO4 and not H3PO4. I don't get 0.0569 M for K3PO4. I find M K3PO4 = mols K3PO4/L = 0.015/0.2 = ?

Answer 2

Okay thank you