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Which compound has highest SRP (standard reduction potential) value, e.g. the strongest oxidising agent? In most tables $\ce{F2}$ is at top with $E^\circ = \pu{2.87 V}$, but I've found a table listing $\ce{H4XeO6}$ at top with $E^\circ = \pu{3.0 V}$.

Is there a more strongest oxidising agent on basis of $E^\circ$ value and is $E^\circ$ value defined for every compound? If yes, what is $E^\circ$ value for $\ce{ClF3}$?

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  • $\begingroup$ SRP is not an attribute of a compound, rather of a redox pair. Probably it would be a good idea to provide such pairs for the compounds you mentioned to begin with. Also, note that SRP is not dimensionless and is measured in Volts (hence the edit). $\endgroup$ – andselisk Jan 20 at 6:57
  • $\begingroup$ @andselisk I think "standard" means not just STP but also paired with standard hydrogen electrode. $\endgroup$ – Night Writer Jan 20 at 9:10
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    $\begingroup$ @TryHard Sure, but that's not what I meant. One must introduce a redox pair befire assigning an SRP: e.g. for $\ce{F2 (g) + 2  e− → 2 F−}$ $E^\circ=\pu{+2.87 V}$, whereas for $\ce{F2(g) + 2 H+ + 2 e- → 2 HF (aq)}$ $E^\circ=\pu{+3.05 V}$. Posting an SRP for $\ce{F2}$ alone doesn't make much sense. To OP: note that for $\ce{KrF2 (aq) + 2 e- → Kr (g) + 2 F- (aq)}$ $E^\circ=\pu{+3.27 V}$ (Wikipedia). $\endgroup$ – andselisk Jan 20 at 9:31
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Top 5 oxidants from the CRC Handbook of Chemistry and Physics [1, p. 5-83]:

TABLE 2. Reduction Reactions Having $E^\circ$ Values More Positive Than That of the Standard Hydrogen Electrode

$$ \begin{array}{ll} \hline \text{Reaction} & E^\circ/\pu{V}\\ \hline \ce{F2 + 2 H+ + 2 e- ⇌ 2 HF} & 3.053\\ \ce{Tb^4+ + e- ⇌ Tb^3+} & 3.1\\ \ce{Pr^4+ + e- ⇌ Pr^3+} & 3.2\\ \ce{Cf^4+ + e- ⇌ Cf^3+} & 3.3\\ \ce{XeF + e- ⇌ Xe + F-} & 3.4\\ \end{array} $$

Note that standard reduction potential is not characteristic for a single compound. Instead, it is only makes sense for a given redox pair – of course, assuming standard conditions ($\pu{298.15 K}$, $\ce{101.325 kPa}$), activity of all soluble species $\pu{1 .000 mol L-1}$ and measured against the standard hydrogen electrode.

For example, iodate $\ce{IO3-}$ has very rich redox chemistry and many SRP values [1, p. 5-79]:

$$ \begin{array}{ll} \hline \text{Reaction} & E^\circ/\pu{V}\\ \hline \ce{2 IO3– + 12 H+ + 10 e- ⇌ I2 + 6 H2O} &1.195\\ \ce{IO3– + 6 H+ + 6 e- ⇌ I– + 3 H2O} &1.085\\ \ce{IO3– + 2 H2O + 4 e- ⇌ IO– + 4 OH–} &0.15\\ \ce{IO3– + 3 H2O + 6 e- ⇌ IO– + 6 OH–}& 0.26\\ \end{array} $$

References

  1. Haynes, W. M.; Lide, D. R.; Bruno, T. J. CRC Handbook of Chemistry and Physics: A Ready-Reference Book of Chemical and Physical Data.; 2017; Vol. 97. ISBN 978-1-4987-5429-3.
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