A model equation of state of chlorinated methane derivatives allowing
for their dissociation is constructed using the single-liquid van der
Waals model and variational theory of equations of state suggested for
dense gases. A comparison of the calculated shock Hugoniots with expe
riment shows the effect of relaxation processes(namely, of slow dissoc
iation relaxation) on the shape of shock Hugoniot. Incorporation in th
e model of a finite dissociation rate yielded good agreement with the
experimental data.