Oxidation half-cell reaction

The following equation represents the oxidation half-cell reaction at the anode where lead is oxidized from the zero oxidation state to the +2 oxidation state. 

The overall reaction is written as the sum of a reduction half-cell reaction and an oxidation half-cell reaction. 

What are the two key pyrite-marcasite oxidation reactions that cause the weathering of FeS2 Compare and discuss the meaning of the acidity produced by the overall oxidation reactions to that of the corresponding oxidation half-cell reactions. 

When the circuit is completed, Zn atoms of the zinc bar dissolve in the ZnS04 solution to form Zn + ions. In this process, two electrons are liberated per atom of Zn dissolved. This oxidation reaction is the anodic reaction, which ultimately eats away the zinc bar. The oxidation half-cell reaction is written as follows ... 

The metal anode oxidation half-cell reaction is usually written as ... 

Fuel cells are electrochemical cells where the chemical energy of the fuel was converted into electricity for power generation with high efficiency [1,2]. Industrial purified hydrogen and air are often used in fuel cells to eliminate any pollution or emission, which is known as proton exchange membrane fuel cells (PEMFCs). In a typical PEMFC, a steam of hydrogen is deUvered to the anode side of the membrane electrode assembly (MEA) [3,4], At the anode, it is catalyzed by platinum (Pt) and split into protons and electrons. This oxidation half-cell reaction is represented as follows ... 

Anode oxidation half-cell reaction 2H2 4H + 4e Cathode reduction half-cell reaction 4H + 4e + O2 —>2H2O Overall reaction 2H2 -h O2 —> 2H2O... 

Anode oxidation half-cell reaction CH3OH-r H2O—>C02-r... 

Because hydrogen is a gas at room temperature, electrodes cannot be constructed from it. The standard hydrogen electrode consists of a piece of platinum dipped into a solution containing 1 M Fl (aq) with a stream of hydrogen passing over its surface. The platinum does not react but provides a surface for the reduction of H30 (aq) to H2(g) as well as the reverse oxidation half-cell reaction. 

We have just seen how to obtain an unknown E° from two known values of E" by working through the expression AjG° = —zFE°. As shown below for a hypothetical displacement reaction, we can similarly calculate an unknown E u through the expression A G = -2FE°eii. (Note that for the oxidation half-cell reaction, A Gqx is simply the negative of the value for the reverse half-cell reaction, ArGred-)... 

A superior form of the Leclanche cell is the alkaline cell, which uses NaOH or KOH in place of NH4CI as the electrolyte. The reduction half-cell reaction is the same as that shown above, but the oxidation half-cell reaction involves the formation of Zn(OH)2(s), which can be thought of as occurring in two steps. 

The pink color results from the indicator phenolphthalein in the presence of base the dark blue color results from the formation of Turnbull s blue KFe[Fe(CN)6]. Corrosion (oxidation) of the nail occurs at strained regions (a) the head and tip and (b) a bend in the nail, (c) Contact with zinc protects the nail from corrosion. Zinc is oxidized instead of the iron (forming the faint white precipitate of zinc ferricyanide). (d) Copper does not protect the nail from corrosion. Electrons lost in the oxidation half-cell reaction distribute themselves along the copper wire, as seen by the pink color that extends the full length of the wire. 

In the electrolysis of aqueous sodium chloride with inert electrodes, there are two possible reduction half-cell reactions and txvo possible oxidation half-cell reactions. 

Oxidation always occurs at the anode of an electrochemical cell. Because of the buildup of electrons freed in the oxidation half-cell reaction, the anode of a voltaic cell is (-). Because electrons are withdrawn from it, the anode in an electrolytic cell is (-I-). For both cell types, the anode is the electrode from which electrons exit the cell. 

On page 901 we described the electrolysis of NaCl(aq) through the reduction half-cell reaction (19.30) and the oxidation half-cell reaction (19.31). 

Electrochemistry plays a key role in corrosion and its control. Oxidation half-cell reactions produce anodic regions and reduction half-cell reactions cathodic regions. Cathodic protection is achieved when a more active metal is attached to the metal being protected from corrosion. The more... 

The anode is the electrode in an electrochemical cell at which an oxidation half-cell reaction occurs. Groups bonded to adjacent carbon atoms (in a carbon-carbon single bond) are said to be in an anti conformation if the dihedral angle between the groups is 180°. 

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