Răspuns:
98g..............142g
2NaOH + H2SO4 => Na2SO4 + 2H2O
5,2g.............xg
MH2SO4 =2×1+32+4×16=98g/mol
MNa2SO4=2×23+32+4×16=142g/mol
x= 5,2×142/98=calculează