3 NaOH + H3PO4 ---> 3 H2O + Na3PO4
25+375=400 g =>c%=25/400*100=6,25%
3*40 g NaOH......1 mol H3PO4
25 g NaOH.......x moli H3PO4 x = 0,20833 moli
cM=nr moli/volum=0,20833/0,2=1.04165 moli/litru
3*40 g NaOH.....164 g Na3PO4
25 g NaOH.........x g Na3PO4 x = 34,166 g Na3PO4