posted by emman .
3. The solubility of BaSO4 at 25C is 9.04 mg/L. Based on this, how many grams and moles of BaSO4 remained dissolved in the 100 mL of solution? What percent of your yield does this represent?
2. The precipitate is washed with warm water not cold, why is this? What might happen if cold water was used? How would this affect the measured yield of BaSO4?
3. Solubility is 9.04 mg/L; therefore, in 100 mL, the solubility is 9.04 mg x 100/1000 = ?
I don't know the percent of the yield since you didn't give a quantity you collected.
2. You want to avoid peptization; i.e., colloid formation. Of course, BaSO4 is more soluble in hot water than cold water so there will be some extra loss due to increased solubility in warm water; however, most procedures call for adding an excess of the precipitating agent and that decreases the solubility due to Le Chatelier's Principle.