Task 4: Fluoride Treatment and Removal
Q1: We have not been able to get our calcium sulfate to dissolve. What should we do?
A1: The task statement says that the test solution will contain 1.7 grams of calcium sulfate per liter of solution. According to the literature, the solubility of calcium sulfate in water at 20C is 0.2 grams/100 ml of water (solubilities are always expressed as per 100 ml of water). This translates to 2 grams/liter, which is more than the task calls for, so one would expect to be able to dissolve 1.7 grams per liter. So I don’t know why you are having trouble getting it to dissolve.
Please check back regularly for more FAQs.