# What is the concentration of the unknown H3PO4 solution? The neutralization reaction is H3PO4(aq)+3NaOH(aq)→3H2O(l)+Na3PO4(aq)

Jun 12, 2017

For a start your reaction is.........

${H}_{3} P {O}_{4} \left(a q\right) + 2 N a O H \left(a q\right) \rightarrow N {a}_{2} H P {O}_{4} \left(a q\right) + 2 {H}_{2} O$

#### Explanation:

Phosphoric acid is a DIACID in aqueous solution; and you should point this out to your prof.

And thus $\text{moles of NaOH} = 26.28 \times {10}^{-} 3 L \times 0.100 \cdot m o l \cdot {L}^{-} 1$

$\equiv 2.63 \times {10}^{-} 3 \cdot m o l$

And thus $\text{concentration } {H}_{3} P {O}_{4} = \frac{2.63 \times {10}^{-} 3 \cdot m o l \times \frac{1}{2}}{32.00 \times {10}^{-} 3 L}$

$= 4.11 \times {10}^{-} 2 \cdot m o l \cdot {L}^{-} 1.$

$\text{I reiterate that phosphoric acid is a diacid and not a triacid.}$