Question

For the standardization of their sodium hydroxide solution a pair of students weighed out 0.5342 g of KHP (MM 204.22 g/mol). They found that it took 21.36 mL of their NaOH solution to reach the endpoint. What is the concentration of their NaOH solution?

Answer 1

Answer:

The concentration of their NaOH solution is 0.1225 M.

Explanation:

Moles of KHP :

Given, Mass of KHP = 0.5342 g  

Molar mass of KHP = 204.22 g/mol

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$Moles= \frac{0.5342\ g}{204.22\ g/mol}$

$Moles\= 2.6158\times 10^{-3}\ mol$

According to the reaction shown below:

KHP + NaOH ⇒ KNaP + H₂O

1 mole of KHP reacts with 1 mole of NaOH

So,

$2.6158\times 10^{-3}\ mol$ of KHP reacts with $2.6158\times 10^{-3}\ mol$ of NaOH

Moles of NaOH = $2.6158\times 10^{-3}\ mol$

Volume = 21.36 mL = 0.02136 L ( 1 mL = 0.001 L)

The expression for molarity is:-

$Molarity=\frac{Moles\ of\ solute}{Volume\ of\ the\ solution}$

$Molarity_{NaOH}=\frac{2.6158\times 10^{-3}}{0.02136}$

$Molarity_{NaOH}=0.1225\ M$

The concentration of their NaOH solution is 0.1225 M.