J.R. S. answered 05/13/19
Ph.D. University Professor with 10+ years Tutoring Experience
Ba(OH)2 + H2SO4 ==> BaSO4 + 2H2O ... balanced equation
moles H2SO4 present = 5.0 ml x 1 L/1000 ml x 1.3 mol/L = 0.0065 moles H2SO4
moles Ba(OH)2 needed to neutralize this = 0.0065 moles Ba(OH)2 since mole ratio is 1:1
volume Ba(OH)2 needed to obtain 0.0065 moles: (x L)(0.023 mol/L) = 0.0065 moles
(x L)(0.35 mol/L) = 0.0065 moles
x = 0.02826 L x 1000 ml/L = 28.26 ml = 28 mls Ba(OH)2 needed (to 2 significant figures)