The thermodynamics of excited nuclear systems allows the exploration of a phase transition in a two-component quantum mixture. Temperatures and densities are derived from quantum fluctuations of fermions. The pressures are determined from the grand partition function of Fisher's model. Critical scaling of observables is found for the first time for fragmenting systems which differ in neutron to proton concentrations thus constraining the equation of state (EOS) of asymmetric nuclear material. The derived critical exponent, = 0.35 0.01, belongs to the liquidgas universality class. The critical compressibility factor Pc/cTc increases with increasing neutron concentration, which could be due to finite-size and/or Coulomb effects.