Solubility
The solubility of the various alums in water varies greatly, sodium alum being readily soluble in water, while caesium and rubidium alums are only sparingly soluble. The various solubilities are shown in the following table.
- At temperature T, 100 parts water dissolve:
| T | Ammonium alum | Potassium alum | Rubidium alum | Caesium alum |
|---|---|---|---|---|
| 0 °C | 2.62 | 3.90 | 0.71 | 0.19 |
| 10 °C | 4.50 | 9.52 | 1.09 | 0.29 |
| 50 °C | 15.9 | 44.11 | 4.98 | 1.235 |
| 80 °C | 35.20 | 134.47 | 21.60 | 5.29 |
| 100 °C | 70.83 | 357.48 |
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