I need to prepare a 1.3 M Aluminium sulfate (anhydrous 99.99% - metal basis) solution, so based on its molar mass (342 g/mol) I need around,44.46 g of Aluminium sulfate in 100 ml of water to make it. However, the solubility of Aluminium sulfate is 38.5 g per 100 ml of water at 25 Deg C (According to a CRC handbook). We tried to dissolve around 2 g in 50 ml of water but we were not successful. Is there a better method to do this accurately? Does increasing the temperature helps? I appreciate any advice.
Thanks
Dear Dr. Cristian Fabian Jaimes Saavedra,
increasing the temperature the situation varies greatly as the solubility in water varies greatly.
Solubility in water (g / 100ml)
Dissolved for 100 ml of water at different temperatures (℃) in grams:
31.2g / 0 ℃; 33.5g / 10 ℃; 36.4g / 20 ℃; 40.4g / 30 ℃; 45.8g / 40 ℃, 59.2g / 60 ℃; 73g / 80 ℃; 80.8g / 90 ℃; 89g / 100 ℃.
Source: https://www.chemicalbook.com/ChemicalProductProperty_EN_CB8435192.htm
Another effect to consider is increase in specific gravity. The water volume in the solution will shrink to compensate the final specific gravity. This will saturate the solution and will precipitate to accommodate specific gravity and normal solution to the temperature.
This chart may help you to evaluate the ratios of sulfate weight and water volume impacts the specific density the Aluminum Sulfate solution (http://pubs.acs.org/doi/abs/10.1021/ie50430a030).
Good work and best regards, Pierluigi Traverso
- Badges
- Science topic