Fig A shortcircuited electrochemical cell for carrying out reaction

compartments called electrodes or half-cells. These are joined by a bridge called a .solid electrolyte, which is a fast conductor of oxygen ions. A typical solid electrolyte is ZrO2 doped with CaO to enhance oxygen mobility. The compartment containing X and XO is called the cathode because reduction of X2+ (in XO) to X occurs here. The oxygen ions liberated at the cathode diffuse through the solid electrolyte. Upon reaching the opposite electrode, oxygen ions react with metal Y to form YO, releasing two electrons to the external circuit. Because Y is oxidized to Y2+ (in YO), this electrode is termed the anode. The electrons liberated at the anode supply the reduction reaction occurring in the cathode.

In the electrochemical cell, the overall reaction (10.1) is physically separated into two half-cell reactions that differ from formation reactions such as (10.2) by explicitly showing the oxygen ions and the electrons:

XO + 2e ^ (O2-)cathode + X Y + (O2-)mode ^ YO + 2e (10.3)

The reaction on the left is called the cathodic reaction and the right side is the anodic reaction. The sum of these half-cell reactions is the overall cell reaction of (10.1).

The short-circuited cell of Fig. 10.1 serves no practical purpose other than allowing reaction (10.1) to proceed from left to right. The chemical energy released by the reaction is dissipated as heat.

Getting Started With Solar

Getting Started With Solar

Do we really want the one thing that gives us its resources unconditionally to suffer even more than it is suffering now? Nature, is a part of our being from the earliest human days. We respect Nature and it gives us its bounty, but in the recent past greedy money hungry corporations have made us all so destructive, so wasteful.

Get My Free Ebook

Post a comment