Question

Initially a NaOH solution was standardized by titration with a sample of potassium hydrogen phthalate, KHC8H4O4, a monoprotic acid often used as a primary standard. A sample of pure KHC8H4O4 weighing 1.518 grams was dissolved in water and titrated with the NaOH solution. To reach the equivalence point, 26.90 milliliters of base was required. Calculate the molarity o

Answer 1

0.2763M NaOH

Step-by-step explanation:

Based on the reaction of hydrogen phtalate, KHP, with sodium hydroxide, NaOH:

KHP + NaOH → KNaP + H₂O

1 mole of KHP reacts per mole of NaOH.

In the equivalence point, the moles of NaOH added = Moles of KHP that were dissolved.

Thus, to solve this question, we must find the moles of KHP = Moles NaOH. With the moles and the volume of NaOH required to reach the equivalence point we can find molarity of NaOH solution:

Moles KHP = Moles NaOH (Molar mass KHP = 204.22g/mol):

1.518g * (1mol / 204.22g) = 7.433x10⁻³ moles NaOH

In 26.90mL = 0.0269L:

7.433x10⁻³ moles NaOH / 0.02690L

0.2763M NaOH