Final answer:
To find the mass of KClO₃ deposited upon cooling, identify the solubility at 90°C and 40°C using a solubility curve, then calculate the mass based on the volume of the solution.
Step-by-step explanation:
To calculate the mass of KClO₃ crystals that will be deposited when a saturated solution is cooled from 90°C to 40°C, one needs to know the solubility of KClO₃ at these temperatures. Although the exact solubility values are not provided in the question, the process to find the mass would involve looking at a solubility curve for KClO₃, determining the solubility at 90°C and 40°C, and then calculating the difference in solubility. This difference, multiplied by the volume of the solution, would give the mass of KClO₃ that precipitates out.
For instance, if the solubility at 90°C is 'X' grams per 100 mL and at 40°C it is 'Y' grams per 100 mL, the amount precipitating out from 50 mL of solution would be ((X - Y)/100) × 50 grams. This type of question requires the solubility data for KClO₃, which typically would be found on a solubility curve.