Question

What volume of 0.20 M H3PO4 is needed to react with 100 mL of 0.1 M NaOH?H3PO4 + 3NaOH Na3PO4 + 3H2O

Answer 1

Based on the chemical equation the acid to base mole ratio is 1:3

First we must determine the number of moles in 100 mL 0f 0.1 M NaOH:

$mole=\text{ }\frac{0.1\text{ }mol\times100\text{ }mL}{1000\text{ }mL}$

mole = 0.01 NaOH

By using the mole ratio 1:3 to determine how many moles of H3PO4 reacted

mole =0.01/3

mole = 0.0033 H3PO4

Volume of H3PO4 needed to react with NaOH is:

$volume=\frac{0.0033\text{ }mol\times1000\text{ }mL}{0.2\text{ }mol}$

volume = 16.6 mL