J.R. S. answered 07/06/21
Ph.D. University Professor with 10+ years Tutoring Experience
HBr + NaOH ==> NaBr + H2O ... balanced equation
mols NaOH present = 40.00 ml x 1 L / 1000 ml x 0.8000 mol / L = 0.0320 mols NaOH
mols HBr needed = 0.0320 mols (since mol ratio is 1:1)
volume HBr needed:
(x L)(0.2400 mol/L) = 0.0320 mols
x = 0.1333 liters = 133.3 mls