A 20.0 mL solution of NaOH is neutralized with 34.3 mL of 0.200 M HBr. What is the concentration of the original NaOH solution?

Answer 1

NaOH + HBr ==> NaBr + H₂O

moles HBr used = 0.0343 L x 0.200 mol/L = 0.00686 moles

moles NaOH = 0.00686 b/c it’s a 1:1 mol ratio with HBr

Concentration of NaOH = 0.00686 mol/0.020 L = 0.343 M