1. The problem statement, all variables and given/known data What is the final concentration of hydroxide (OH) ions when 2.00 L of 0.100 M Ba(OH)2 is combined with 1.00 L of 5.00*10^-3 M H3PO4 and allowed to react to completion? 2. Relevant equations Chemical Equation that's balanced is: 3Ba(OH)2 + 2H3PO4 --> Ba3(PO4)2 +6H20 3. The attempt at a solution To start off, i found that H3PO4 is the limiting reactant so used the mols of that to calculate hydroxide ions. Therefore, 0.005 mols H3PO4 * (6 mols OH/2 mols H3PO4) = 0.15 mols OH so .15 / 3 liters = 0.05 M (but the answer is 0.128 M!) Can someone help me!