Final answer:
The volume of 0.0826 M KOH needed to reach the equivalence point in the titration of 23.4 mL of 0.0390 M HNO₂ is 11.05 mL. The pH of the equivalence point will be greater than 7 due to the hydrolysis of the conjugate base formed from the weak acid HNO₂ by the strong base KOH.
Step-by-step explanation:
To find the pH of the equivalence point and the volume of 0.0826 M KOH needed to reach the equivalence point in the titration of 23.4 ml of 0.0390 M HNO₂, one must first calculate the moles of HNO₂ present.
Moles of HNO₂ = volume (L) × molarity = 0.0234 L × 0.0390 M = 0.0009126 moles.
Since the reaction between HNO₂ and KOH is a 1:1 mole ratio, the same number of moles of KOH are needed to reach the equivalence point.
The volume of KOH required is calculated by:
Volume of KOH = moles of KOH / molarity of KOH
= 0.0009126 moles / 0.0826 M
= 0.01105 L
= 11.05 mL
As HNO₂ is a weak acid and KOH is a strong base, the conjugate base formed will hydrolyze water, creating a basic solution at the equivalence point.
The pH is higher than 7, and can be found by calculating the pOH from the concentration of the conjugate base and then converting to pH.