xg 980g
2 NaOH + H2SO4= Na2SO4 +2 H2O
2.40g 98g
x=2.40 .980 :98=800g NaOH
n=m : M [ n=nr. moli ; m=masa subst. ; M=masa molara ]
n=800g : 40g/moli=20moli NaOH
( am calculat si molii , poate ai nevoie )
MNaOH=23+16+1=40----->40g/moli
MH2SO4=2+32+4.16=98----->98g/moli