Answer:
146 mL
Explanation:
Step 1: Write the balanced equation
H₃PO₄ + 3 NaOH ⇒ Na₃PO₄ + 3 H₂O
Step 2: Calculate the reacting moles of sodium hydroxide
119 mL of 0.315 M NaOH react.
[tex]0.119L \times \frac{0.315mol}{L} = 0.0375mol[/tex]
Step 3: Calculate the reacting moles of phosphoric acid
The molar ratio of H₃PO₄ to NaOH is 1:3. The reacting moles of H₃PO₄ are 1/3 × 0.0375 mol = 0.0125 mol.
Step 4: Calculate the reacting volume of phosphoric acid
0.0125 moles of H₃PO₄ are in a 0.0855 M solution.
[tex]0.0125 mol \times \frac{1L}{0.0855mol} \times \frac{1,000mL}{1L} =146 mL[/tex]
