Table 5.
Predicted switch concentration (density-only) at which the brine density equals the cresol density (
), implying a transition from sinking to floating under the perfect-separation assumption (droplet density = neat cresol) and neglecting droplet-floc entrainment. Switch concentrations are reported as molality ( m, mol kg−1 H2O) for direct comparison to density correlations; experimentally prepared solutions are described by molarity (M). At 20 °C, these switch molalities correspond approximately to 
0.22–0.33 M for the divalent salts and 
0.9 M for NaCl. Differences between m- and p-cresol thresholds are negligible (
0.003 m) because their densities are nearly identical
| Salt | Switch molality m (mol/kg H2O) (m-cresol) | Switch molality m (mol/kg H2O) (p-cresol) |
|---|---|---|
| NaCl | 0.903 | 0.906 |
| CuCl2 | 0.295 | 0.296 |
| CuSO4 | 0.224 | 0.225 |
| ZnCl2 | 0.289 | 0.290 |
| ZnSO4 | 0.219 | 0.220 |
| FeCl2 | 0.330 | 0.331 |
| FeSO4 | 0.237 | 0.238 |