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Latimer diagrams can be used in the construction of Frost diagrams, as a concise summary of the standard electrode potentials relative to the element.Since Δ r G o = -nFE o, the electrode potential is a representation of the Gibbs energy change for the given reduction.
Pourbaix diagram of iron. [1] The Y axis corresponds to voltage potential. In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E H –pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases (i.e., at chemical equilibrium) of an aqueous electrochemical system.
Both the oxidation and reduction steps are pH dependent. Figure 1 shows the standard potentials at pH 0 (strongly acidic) as referenced to the normal hydrogen electrode (NHE). 2 half reactions (at pH = 0) Oxidation 2H 2 O → 4H + + 4e − + O 2 E° = +1.23 V vs. NHE Reduction 4H + + 4e − → 2H 2 E° = 0.00 V vs. NHE
In the Bashkirov process, the autoxidation is conducted in the presence of boric acid, yielding an intermediate borate ester. The process is more selective with the boric acid, but the conversion to the alcohol requires hydrolysis of the ester. This approach continues to be used in the production of cyclododecanol from cyclododecane.
The Frost diagram is also a useful tool for comparing the trends of standard potentials (slope) of acidic and basic solutions. The pure, neutral element transitions to different compounds depending whether the species is in acidic and basic pHs. Though the value and amount of oxidation states remain unchanged, the free energies can vary greatly.
A redox gradient is a series of reduction-oxidation reactions sorted according to redox potential. [ 4 ] [ 5 ] The redox ladder displays the order in which redox reactions occur based on the free energy gained from redox pairs.
The chain of redox reactions driving the flow of electrons through the electron transport chain, from electron donors such as NADH to electron acceptors such as oxygen and hydrogen (protons), is an exergonic process – it releases energy, whereas the synthesis of ATP is an endergonic process, which requires an input of energy.
Rather than combustion, organisms rely on elaborate sequences of electron-transfer reactions, often coupled to proton transfer. The direct reaction of O 2 with fuel is precluded by the oxygen reduction reaction, which produces water and adenosine triphosphate. Cytochrome c oxidase affects the oxygen reduction reaction by binding O 2 in a heme ...