a)
2 NaOH + H2SO4➞Na2SO4 + 2H2O
......3.......1.5..........1.5..........3..(mol)
2KOH + H2SO4 ➞ K2SO4 + 2 H2O
..1.........0.5............0.5.......1.....(mol)
b) nH2SO4=196/98=2(mol)
nNaOH=60/40=1.5(mol)
nH2SO4 (phản ứng với KOH)=2-1.5=0.5(mol)
mdd=(1*56)*100/40=140(g)