A volumetric pipet is used to transfer 15 mL of 6.101×10 2 M potassium hydrogen

Question

A volumetric pipet is used to transfer 15 mL  of 6.101×102 M  potassium hydrogen phthalate, a weak acid primary standard with a molecular weight of 204.23 g/mol, into an Erlenmeyer flask with 75 mL of deionized water and 2 drops of phenolphthalein indicator. An approximately 0.2 M NaOH solution is titrated with the acid solution, and at the endpoint 21.93 mL  of NaOH solution were dispensed from the burette. The molecular reaction is HKC8H4O4 (aq) + NaOH (aq) NaKC8H4O4 (aq) + H2O (l).

Part A

How many moles of potassium hydrogen phthalate are used for the titration? Report your answer to 4 significant figures.

Part B

How many moles of NaOH are used for the titration?

Part C

What is the concentration in molarity of the NaOH solution?

Explain steps please, I'm really confused as to what to do..

Explanation / Answer

HKC8H4O4 (aq) + NaOH (aq) NaKC8H4O4 (aq) + H2O (l).

part A

no of mol of potassium hydrogen phthalate used = 15*0.06101/1000 = 0.0009152 mol

part B

1 mol HKC8H4O4 = 1 mol NaOH,

so that,

no of mol of NaOH used = 0.0009152 mol

part C

concentration of the NaOH solution = n/v

       = 0.0009152/21.93*1000

       = 0.04173 M

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