J.R. S. answered 02/07/22
Ph.D. University Professor with 10+ years Tutoring Experience
2HBr + Ba(OH)2 ==> 2H2O + BaBr2 ... balanced equation
moles HBr present = 150.0 mls x 1 L / 1000 mls x 0.130 mol/L = 0.0195 mols HBr
moles Ba(OH)2 needed = 0.0195 mol HBr x 1 mol Ba(OH)2 / 2 mol HBr = 0.00975 mol Ba(OH)2
Volume Ba(OH)2 needed = 0.00975 mol Ba(OH)2 x 1 L / 0.0200 mol = 0.488 L = 488 mls (3 sig. figs.)