J.R. S. answered 03/20/22
Ph.D. University Professor with 10+ years Tutoring Experience
Ba(OH)2 + 2HCl ==> BaCl2 + 2H2O ... balanced equation
moles HCl present = 39.0 ml x 1 L / 1000 ml x 0.181 mols/L = 0.007059 moles HCl'
moles Ba(OH)2 needed = 0.007059 mols HCl x 1 mol Ba(OH)2 / 2 mols HCl = 0.003530 moles Ba(OH)2 needed
volume (mls) Ba(OH)2 needed = 0.003530 mols Ba(OH)2 x 1 L / 0.318 mols = L x 1000 ml/L = 11.1mls needed