80g.............98g.............142g...........36g
2NaOH + H2SO4 => Na2SO4 + 2H2O
x=12g.........14.7g..........Z=21.3g.......y=5.4g
mNaOH exces=20-12=8g
Cp=md/ms*100=>md=49*30/100=14.7g H2SO4
ms=md+mH2O=>mH2O=30-14.7=15.3g
mdf=21.3+8=29.3g
msf=15.3+29.3+5.4=50g
msf=mdf+mfH2O=>mfH2O=msf-mdf=50-29.3=20.7g