Chapter 14, Problem 72A

Interpretation Introduction

Interpretation:

Volume of thesolution is to be calculated.

Concept introduction:

Molarity: Molarity is defined as the number of moles of solute present in one litre of the solution In expression, $\mathrm{Molarity}ofthesolution=\frac{Numberofmolesof the solute}{ Volume of the solution(inlitre)}$

$\mathrm{Number}ofmolesofsolute=\frac{Massofthesolute}{Molecularweightofthesolute}$

Answer to Problem 72A

Volume of LiFsolution is 1.57.

Explanation of Solution

Given information:

Mass of $LiF$ = 122 gm

Molarity of the $LiF$ solution = 3.00 M

Write the expression for the molality of solution.

$\begin{array}{l}Molarityofthesolution=\frac{Numberofmolesof the solute}{ Volume of the solution(inlitre)}\\ Volume of the solution(inlitre)=\frac{Numberofmolesof the solute}{ Molarityofthesolution}\end{array}$

Substitute the values in above equation to calculate the number of moles of solute.

$\begin{array}{l}Numberofmolesofsolute=\frac{Massofthesolute}{Molecularweightofthesolute}\\ NumberofmolesofLiF=\frac{MassofLiF}{MolecularweightofLiF}\\ NumberofmolesofLiF=\frac{122gm}{25.9gm/mol}=4.71mole\end{array}$

(Note: Molecular weight of LiF = 25.9 gm/mol)

Calculate the volume of $LiF$ solution.

$\begin{array}{l}Volume of LiF solution(inlitre)=\frac{Numberofmolesof LiF}{ MolarityofLiFsolution}\\ Volume of LiF solution=\frac{4.71mole}{ 3.0mole/litre}=1.57litre\end{array}$

Volume of LiFsolution is 1.57.