md=30*49/100=14.7g H2SO4
mH2O=ms-md=30-14.7=15.3g H2O
20-12=8g NaOH raman nereactionat
80g..........98g................142g..........36g
2NaOH + H2SO4 ---> Na2SO4 + 2H2O
12g...........14.7g...........x=21.3g......y=5.4g
mH2O final = 5.4+15.3=20.7g
msf=20.7+21.3+8=50g
Cp=md*100/ms=2130/50=42.6% sol. Na2SO4