1) NaH2PO4+2NaOH→Na3PO4+H2O
2) Thus according to this reaction 1m ofNaH2PO4 react with 2mol ofNaOH.
Molar mass ofNaH2PO4=120g/mol
Number of moles of NaH2PO4 in 12g=0.1mol
Thus number of moles of NaOHrequired for complete reaction to occur=2×0.1mol=0.2mol
3) Thus 0.2molNaOH is required for complete reaction.
Since molarity of NaOHis given to be1mol/L
This means volume of 1mol NaOH=1L
Thus volume of 0.2mol NaOH=1×0.2L=0.2L
=0.2×1000mL=200mL
4) Therefore 200mL of 1MNaOHshould be added to 12g NaH2PO4 to exactly convert it into Na3PO4.