Vdd H2SO4=100ml=0,1 lit
=> nH2SO4=CM.V=0,01.0,1=0,001(mol)
PT: H2SO4 + Ba(OH)2 -> BaSO4\(\downarrow\) +2H2O
cứ: 1.................1...................1 (mol)
vậy: 0,001----->0,001--------->0,001(mol)
=> CM Ba(OH)2=n/V=0,001/0,4=0,0025(M)
mBaSO4=n.M=0,001.233=0,233(g)
Vậy a=0,0025 , a=0,233