Chapter 19, Problem 19.144SP

Interpretation Introduction

Interpretation:

The time required to produce the given amount of Al₂O₃ needs to be determined.

Concept introduction:

Anodizing is the process that oxidized a metal anode to yield a porous metal oxide coating that can incorporate dye molecules to give brilliant colors. Following are the cathode, anode and overall reactions for the anodizing of aluminum.

Cathode reaction of anodizing = $6{\text{H}}^{+}(aq)+6e\to 3{\text{H}}_{\text{2}}(aq)$

Anode reaction of anodizing = $2\text{Al}(s)+{\text{3H}}_{\text{2}}\text{O}(l)\to {\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}(s)+6{\text{H}}^{+}(aq)+6e^{-}$

Overall reaction = $2\mathrm{Al}(s)+3{\text{H}}_{\text{2}}\text{O}(l)\to {\text{Al}}_{\text{2}}{\text{O}}_{\text{3}}(s)+3{\text{H}}_2(g)$

The amount of substance produced at an electrode by electrolysis depends on the quantity of charge passed through the cell.

$\text{Charge}(C)=\text{ Current}(A)\times \text{Time}(s)$