md =masa dizolvatului md=0,025 kmoli NaOH ( soda caustica)
ms =masa solutiei MNaOH=23+16+1=40
c=concentratia solutiei 40 kgNaOH-----------1kmoli NaOH
a----------------------0,025 kmoli
c=md.100:ms
ms-md.100:c a=40.0,025=1kg NaOH
ms=1.100:20=5 kg sol.
ms=md +mapa
mapa=ms - md
mapa=5-1=4 kg