We investigate the difference between Amagat and Dalton mixing laws for gaseous equations of state (EOS) using planar traveling shocks. Numerical modeling was performed in the Sandia National Laboratories hydrocode CTH utilizing tabular EOS in the SESAME format. Numerical results were compared to experimental work from the University of New Mexico Shock Tube Laboratory. Latin hypercube samples were used to assess model sensitivities to Amagat and Dalton EOS. We find that the Amagat mixing law agrees best with the experimental results and that significant difference exist between the predictions of the Amagat and Dalton mixing methods