181k views
1 vote
A solution of the primary standard potassium hydrogen phthalate (KHP), KHC8H4O4 , was prepared by dissolving 0.4877 g of KHP in about 50 mL of water. Titration of the KHP solution with a KOH solution of unknown concentration required 26.12 mL to reach a phenolphthalein end point. What is the concentration of the KOH solution?

1 Answer

3 votes

Answer: The molarity of KOH solution is 0.092 M.

Step-by-step explanation:

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


\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

Given mass of KHP = 0.4877 g

Molar mass of KHP = 204.22 g/mol

Putting values in equation 1, we get:


\text{Moles of KHP}=(0.4877g)/(204.22g/mol)=0.0024mol

The chemical reaction for the formation of chromium oxide follows the equation:


KHC_8H_4O_4(aq.)+KOH\rightarrow K_2C_8H_4O_4(aq.)+H_2O(l)

By Stoichiometry of the reaction:

1 mole of KHP reacts with 1 mole of KOH.

So, 0.0024 moles of KHP will react with =
(1)/(1)* 0.0024=0.0024mol of KOH.

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


\text{Molarity of the solution}=\frac{\text{Moles of solute}}{\text{Volume of solution (in L)}}

We are given:

Moles of KOH = 0.0024 moles

Volume of solution = 26.12 mL = 0.02612L (Conversion factor: 1L = 1000 mL)

Putting values in above equation, we get:


\text{Molarity of NaOH }=(0.0024mol)/(0.02612L)=0.092M

Hence, the molarity of KOH solution is 0.092 M.

User Robert Columbia
by
9.4k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.