Chapter 14, Problem 63A

Interpretation Introduction

Interpretation:

The difference between molarity and molality have to be explained.

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.

Molarity: Molarity can be defined as the number of moles of solute present in one litre of the solution and is expressed as:

$\mathrm{Molarity}ofthesolution=\frac{Numberofmolesof the solute}{ Volume of the solution(inlitre)}$

Molality: Molality (m) is defined as the number of moles of the solute per kilogram (kg) of the solvent and is expressed as:

$\mathrm{Molality}ofthesolution=\frac{Numberofmolesof the solute}{Massof the solvent(inkg)}$

Answer to Problem 63A

Molarity is expressed as the moles of solute per volume of solution andmolality represents concentration as moles of solute per kilogram of solvent. Molality does not depend upon the temperature of the solutionwhereas molarity are function of temperature.

Molarity is expressed as the moles of solute per volume of solution. Molality represents concentration as moles of solute per kilogram of solvent. Molarity is denoted by ‘M’ and its unit is mole/litre whereas molality is denoted by ‘m’ and its unit is mole/kg. Molality does not depend upon the temperature of the solutionwhereas molarity are function of temperature.

Explanation of Solution

Molarity is expressed as the moles of solute per volume of solution. Molality represents concentration as moles of solute per kilogram of solvent. Molarity is denoted by ‘M’ and its unit is mole/litre whereas molality is denoted by ‘m’ and its unit is mole/kg. Molality does not depend upon the temperature of the solutionwhereas molarity are function of temperature.