Question

How many milliliters of 0.653 M NaOH are needed to neutralize 25.0 mL of a 1.02 M HBr solution? The neutralization reaction is: NaOH(aq) + HBr(aq) → H2O(l) + NaBr(aq)

Answer 1

NaOH(aq) + HBr(aq) → H₂O(l) + NaBr(aq)

25.0 mL of a 1.02M HBr solution contains $n(HBr)=c(HBr)\cdot V(HBr) = 1.02\frac{mmol}{mL}\cdot 25.0 mL = 25.5 mmol$ HBr. According to stoichiometry of the reaction the same amount of NaOH is required for neutralisation of HBr:

$n(NaOH)=n(HBr)=25.5 mmol$

Volume of NaOH solution can be calculated:

$V(NaOH)=\frac{n(NaOH)}{c(NaOH)}=\frac{25.5mmol}{0.653\frac{mmol}{mL}}=39.1 mL$