Question

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

A 25.00mL sample of an unknown H3PO4solution is titrated with a 0.100M NaOH solution. The equivalence point is reached when 27.43mLof NaOH solution is added.

Answer 1

moles NaOH = M NaOH x L NaOH = (0.100)(0.02743) = 0.00274 moles NaOH

0.00274 moles NaOH x (1 mole H3PO4 / 3 moles NaOH) = 0.000913 moles H3PO4

moles H3PO4 = M H3PO4 x L H3PO4
0.000913 = M H3PO4 x 0.0250
M H3PO4 = 0.03652 M