A 0.411 g sample of potassium hydrogen phthalate, KHC8H4O4 (MM = 204.44 g/mol) is dissolved in 50 mL of deionized water in a 125-Erlenmeyer flask. The sample is titrated to the phenolphthalein endpoint with 15.17 mL of a sodium hydroxide solution. What is the molar concentration of the NaOH solution?

The molarity of NaOH solution is 0.1325 M.

Explanation:

To calculate the number of moles, we use the equation:

Given mass of KHP = 0.411 g

Molar mass of KHP = 204.44 g/mol

Putting values in above equation, we get:

The chemical reaction for the reaction of KHP and NaOH follows

By Stoichiometry of the reaction:

1 mole of KHP reacts with 1 mole of NaOH

So, 0.0027 moles of KHP will react with = of NaOH.

To calculate the molarity of NaOH, we use the equation:

We are given:

Moles of NaOH = 0.00201 moles

Volume of solution = 15.17 mL  = 0.01517 L      (Conversion factor:  1 L = 1000 mL)

Putting values in above equation, we get:

Hence, the molarity of NaOH solution is 0.1325 M.

the answer your looking for is c).