Potassium hydrogen phthalate is used as a primary standard in finding the concentration of a solution of sodium hydroxide by the reaction KHC₈H₄O₄ + NaOH → NaKC₈H₄O₄ + H₂O.What is the molarity of the base if 32.75 mL is required to titrate 1.732 g of the primary standard? A)0.5189 M B)0.2590 M C)1.732 M D)3.861 M E)3.275 M

Question

Quizplus · Accepted Answer

First, we need to calculate the number of moles of KHPh (potassium hydrogen phthalate) used in the titration:

mass of KHPh = 1.732 g
molar mass of KHPh = 204.23 g/mol
number of moles of KHPh = (1.732 g) / (204.23 g/mol) = 0.008479 mol

Since the balanced equation tells us that the number of moles of NaOH used in the reaction is equal to the number of moles of KHPh, we can use the volume of NaOH used in the titration to calculate its molarity:

volume of NaOH used = 32.75 mL = 0.03275 L
molarity of NaOH = (number of moles of NaOH) / (volume of NaOH used)
molarity of NaOH = 0.008479 mol / 0.03275 L = 0.2590 M

Therefore, the answer is B.

Potassium Hydrogen Phthalate Is Used as a Primary Standard in Finding