The moles have to be equal. Always start with a balanced equation. This reaction is a double replacement. The basic equation is NaOH + H3PO4 ===> Na3PO4 + HOH
The balanced equation is. 3NaOH + H3PO4 ===> Na3PO4 + 3HOH
moles of NaOH = moles of H3PO4 mols of NaOH = molarity * Volume molarity = 0.35 mol/L Volume = 1.0 L moles NaOH = 0.35 * 1 = 0.35 mols
Find the moles of H3PO4 For every mol of H3PO4 used, you require 3 mols of NaOH 3/1 = 0.35/x 3x = 0.35 x = 0.35/3 x = 0.1167 moles of H3PO4 needed for this reaction.
Now the volume needs to be calculated. n = 0.1167 M = 0.25 mol/L V = ??
Formula M = n/V V = n/M V = 0.1157/0.25 V = 0.467 L
Note: I merely copied the reaction given myself to the next line. I'm not copying from an outside source.
