Comment on "Anomalies in chemical equilibria near critical points"

The apparent enhancement in the extent of the reaction ${\mathrm{N}}_2$ ${\mathrm{O}}_4$ → ${2\mathrm{N}\mathrm{O}}_2$, dissolved in near-critical ${\mathrm{CO}}_2$, an effect measured by Krichevskii, is reconsidered. The data are shown not to be consistent with the enhancement predicted by Procaccia and Gitterman. It is further shown that the entire effect can be quantitatively accounted for as a consequence of critical turbidity. It is concluded that Krichevskii's data cannot be used as an example of the proposed effect of critical points on the extent of a reaction and that great care should be taken when interpreting any data where the effect seems to appear.