Chapter 17, Problem 17.DE

(a)

Interpretation Introduction

Interpretation:

The mass of silver anode which is utilized in electrolysis has to be calculated.

(b)

Interpretation Introduction

Interpretation:

The voltage at which silver bromide deposited from bromide ion has to be calculated.

Concept Introduction:

When the electric current is too small, the voltage of cell is given as

$\text{E = E(cathode)}\text{-}\text{E(anode)}$

E(cathode) is electrode’s potential which is attached to negative terminal of current source.

E(anode) is electrode’s potential which is attached to positive  terminal of current source.

Overpotential: The activation energy of a reaction at an electrode can be overcome by voltage.  The required voltage to apply is called overpotential.

Ohmic potential:  In electrochemical cell, the electrical resistance of a solution while current I flows can be overcome by voltage.  The required voltage to apply is called ohmic potential.

${\text{E}}_{\text{ohmic}}\text{=}\text{IR}$

Concentration Polarization:  It is the change in concentration of products and reactants at electrode’s surface unlike they are same in solution.

(c)

Interpretation Introduction

Interpretation:

The possibility of separation of potassium iodide from potassium bromide has to be determined.

Concept Introduction:

• The solubility product constant ( ${\text{K}}_{\text{sp}}$) is defined as the equilibrium between compound and its ions in an aqueous solution.
• Solubility product is the multiplication of concentration of dissolved ion, raised to the power of coefficients.
• Ionic compound ${\text{A}}_{\text{3}}\text{B}$ ${\text{K}}_{\text{sp}}\text{=}{\left[\text{A}\right]}^{\text{3}}\left[\text{B}\right]$.
• Ion product ( ${\text{Q}}_{\text{c}}$ ) is defined as product of concentration of ions with each concentrations raised to the power of coefficients of ion in the solution.
• ${\text{Q}}_{\text{c}}{\text{ > K}}_{\text{sp}}$ , precipitation will happen
• ${\text{Q}}_{\text{c}}{\text{ is less than K}}_{\text{sp}}$, more solute can dissolve in solution that is no precipitation.
• ${\text{Q}}_{\text{c}}{\text{ is equal to K}}_{\text{sp}}$, no more solute can dissolve or precipitate in solution.