Chapter 18, Problem 18.182P

(a)

Interpretation Introduction

Interpretation:

Molarity of the solution has to be calculated.

Concept Introduction:

Molarity of a solution can be calculated using the following equation.

$Molarity=\frac{numberofmolesofsolute}{Volumeofsolutioninlitre}$

And number of moles of solute can be calculated using the following equation.

$\text{Number of moles = }\frac{\text{Given mass of solute}}{\text{Molecular mass of the solute}}$

Therefore molarity can be calculated as follows,

$Molarity=\frac{numberofmolesofsolute}{Volumeofsolutioninlitre}=\frac{W_2\times 1000}{M_2\times V\left(ml\right)}$

Where,

  $\begin{array}{l}{\text{W}}_{\text{2}}\text{ = given mass of solute}\\ {\text{M}}_{\text{2}}\text{= molecular mass of solute}\\ \text{V}\left(\text{ml}\right)\text{ = volume of solution in ml}\end{array}$

(b)

Interpretation Introduction

Interpretation:

Molarity of propanoate ion has to be calculated.

Concept Introduction:

Colligative properties: It is the property that depends on the amount of solute present in the solution, not on the nature of the solute. Examples for colligative properties are elevation in boiling point, depression in freezing point, relative lowering of vapor pressure and osmotic pressure.

Depression in freezing point: Addition of a solute decreases the freezing point of the pure solvent this phenomenon is called depression in freezing point.

Freezing point depression of a solution can be calculated using the following formula,

${\text{ΔT = i K}}_{\text{f}}\text{m}$

Where,

  $\begin{array}{l}\text{ΔT = depression}\text{in}\text{freezing}\text{point}\text{= difference in temperature of pure solvent and solution}\\ \text{i = van't}\text{hoff}\text{factor}\\ {\text{K}}_{\text{f}}\text{ = cryoscopic constant}\\ \text{m =}\text{molality}\end{array}$

(c)

Interpretation Introduction

Interpretation:

Percentage dissociation of propanoic acid has to be calculated.

Concept Introduction:

Percentage dissociation of propanoic acid can be calculated as follows,

$\text{Percentage dissociation of propanoic acid=}\frac{\text{amount of propanoic acid dissociated}}{\text{total amount of propanoic acid present initially}}\times 100$