Chapter 14, Problem 68A

Interpretation Introduction

Interpretation:

Amount of LiCl present in 275 gm of 15% aqueous solution of LiCl has to be calculated.

Concept introduction:

Composition of a solution can be defined by expressing its concentration. The concentrations of solutions can be expressed in different ways, which are involved in the quantity of solute and the quantity of solution or solvent. Various methods are used to describe the concentration of the solution quantitatively. Some commonly used quantitative concentration terms are percent by mass, percent by volume, molarity, molality and mole fraction.

Mass percentage or percent by mass (w/W %): The mass percentage of a component of a solution is defined as:

$\mathrm{Mass}\%ofacomponent=\frac{Mass of the component in the solution}{Total mass of the solution}\times 100$

Answer to Problem 68A

41.25 gm of LiCl is present in 275 gm of 15% aqueous solution of LiCl.

$\mathrm{Mass}\%ofacomponent=\frac{Mass of the component in the solution}{Total mass of the solution}\times 100$

Data given: Total mass of the solution = 275 gm

Percent by mass = 15

$\begin{array}{l}Masspercentage=\frac{Massof LiClinthesolution}{Total mass of the solution}\times 100\\ Massof LiCl=\frac{Masspercentage\times Total mass of the solution}{100}\\ Massof LiClinthesolution=\frac{15\times 275gm}{100}=41.25gm\end{array}$

Explanation of Solution

$\mathrm{Mass}\%ofacomponent=\frac{Mass of the component in the solution}{Total mass of the solution}\times 100$

Data given: Total mass of the solution = 275 gm

Percent by mass = 15

$\begin{array}{l}Masspercentage=\frac{Massof LiClinthesolution}{Total mass of the solution}\times 100\\ Massof LiCl=\frac{Masspercentage\times Total mass of the solution}{100}\\ Massof LiClinthesolution=\frac{15\times 275gm}{100}=41.25gm\end{array}$