Final answer:
The concentration of the unknown H3PO4 solution can be determined from a titration with 0.0987 M KOH where 54.06 mL was used. By calculating the moles of KOH and accounting for the triprotic nature of H3PO4, the concentration is found to be approximately 0.0711 M.
Step-by-step explanation:
To determine the concentration of the unknown H3PO4 solution, we can use the data provided from the titration with KOH. In a titration, the moles of titrant (in this case, KOH) equal the moles of the analyte (here, H3PO4), according to the balanced chemical equation. Since H3PO4 is a triprotic acid, each mole of it can react with three moles of KOH. The molarity (M) of KOH and the volume (mL) used in the titration are given, allowing us to calculate the moles of KOH. From there, we find the moles of H3PO4, and ultimately the concentration of H3PO4.
Here's the calculation process:
- First, calculate the moles of KOH used: moles KOH = Molarity KOH × Volume KOH (in liters).
- Since the mole ratio of H3PO4 to KOH is 1:3, divide the moles of KOH by 3 to get the moles of H3PO4.
- Finally, divide the moles of H3PO4 by the initial volume of H3PO4 solution (in liters) to get its concentration in molarity (M).
Let's input the values:
- Moles of KOH = 0.0987 M × 0.05406 L = 0.005334262 mol KOH
- Moles of H3PO4 = 0.005334262 mol KOH / 3 = 0.001778087 mol H3PO4
- Concentration of H3PO4 = 0.001778087 mol / 0.02500 L = 0.07112348 M
Therefore, the concentration of H3PO4 is approximately 0.0711 M, to four significant figures.