Question

6. Potassium hydrogen phthalate (KHP, KHC8H4O4) is also a good primary standard. 20 mL of NaOH was titrated with 0.600 M KHC8H4O4 solution. The data was graphed and the equivalence point was found when 15.5 mL of the standard 0.600 M KHP solution was added. The reaction equation is: a. What is the molar ratio of NaOH:KHC8H4O4? b. What is the molarity of the NaOH solution?

Answer 1

Answer:

a. 1

b. 0.465M NaOH

Explanation:

KHP reacts with NaOH as follows:

KHP + NaOH → KP⁻ + Na⁺ + H₂O

a. Molar ratio represents how many moles of NaOH reacts per mole of KHP. As you can see in the reaction, 1 mole of NaOH reacts with 1 mole of KHP. Molar ratio is:

1/1 = 1

b. With volume and molar concentration of the KHP solution you can find how many moles of KHP were added until equivalence point, thus:

15.5mL = 0.0155L ₓ (0.600 moles KHP / L) = 0.0093 moles of KHP

In equivalence point, moles of NaOH = Moles KHP. That means moles of NaOH titrated are 0.0093 moles NaOH.

The volume of the NaOH solution was 20mL = 0.020L. Molarity of the solution is:

0.0093 moles NaOH / 0.020L =

0.465M NaOH