Fluorine standard reduction potentials

The cathode reaction comes directly from a table of standard reduction potentials, while the anode reaction is the reverse reaction from such a table. However, how did we know that it was the fluorine reaction requiring reversal ... 

This reaction has been assigned a potential of 0.000 volts under standard conditions. The standard reduction potential for fluorine gas is 2.890 volts while that for sodium metal is -2.714 volts. 

Notice in Table 22.2 that the standard reduction potential of F2 is exceptionally high. Fluorine gas readily oxidizes water ... 

The trends in the standard reduction potentials of the halogens are closely related to the uniqueness of fluorine. A quick inspection of Table 18.1 indicates that fluorine has the highest standard reduction potential (2.87 V) of the group and that chlorine is a distant second (1.36 V), with the rest of the values steadily decreasing from 1.07 V to 0.3 V after that. Note that the standard reduction potentials correspond to the half-reaction shown in Equation (18.6) ... 

Write a Born-Haber cycle corresponding to the standard reduction potential of fluorine. What thermodynamic properties would be needed to estimate the value of the reduction potential Using your cycle, discuss why the standard reduction potential of fluorine is so extremely positive. 

Use standard reduction potentials to show why sulfuric acid could not be used to oxidize fluorides to fluorine but was used by Courtois to produce iodine from iodides. Why did Courtois have to use concentrated sulfuric acid ... 

Fluorine is a highly reactive gas that attacks water to form HF and other products. Follow the procedure in Problem 19.115 to show how you can determine indirectly the standard reduction potential for fluorine. Compare your result with the value in Table 19.1. 

The chemistry of fluorine is dominated by its electronegativity, which is the highest of all elements. The colorless gas F2 has an estimated standard electrode potential E° (Chapter 15) of +2.85 V for reduction to F (cf. + 1.36 V for Cl2 to Cl-), and thus F2 immediately oxidizes water to oxygen (E° = +1.23 V), and 2% aqueous NaOH to the gas F20. Obviously, F2 cannot be made by electrolysis of aqueous NaF. The usual preparation involves electrolysis of HF-KF melts in a Monel (Cu-Ni alloy) or copper apparatus. 

In another study, the reductive C-F bond cleavage of fluoromethylarenes has been investigated in liquid ammonia and DMF by CV and/or redox catalysis [299]. Within a series of 4-cyanotoluenes where the a-carbon bears one, two or three fluorine atoms, the rate of radical anion cleavage increases on going from the trifluoro to the monofluoro derivative, a behavior which reflects the decrease in both C-F BDE and standard potential, °rx/rx.-, as the number of fluorine atoms is diminished (Table 14). 

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