Critical exponents of a fluid mixture in the presence of isotope exchange: Isobutyric acid/D2O

Experiments on phase diagrams and critical opalescence of a fluid mixture, isobutyric acid in D2O, indicate that the presence of isotope exchange reactions can change the critical behavior of such a system from that of a simple binary fluid mixture. Appreciable amounts of additional species due to isotope exchange distort the coexistence curve, shift the critical solution concentration yc away from the concentration (yI*) where the maximal phase separation temperature Tp,max occurs, and make the critical exponents γ and ν in the one-phase region (T≳Tc) different from those of the coexisting two-phase region (T