# Help with Recrystallization Lab Questions

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Question description

1) The solubility of solid R in water is: 0.71 g/100 mL at 0°C, 24.0g/100 mL at 100°C. a) How many mL of boiling water are required to dissolve 94.5 g of R?(report to the nearest mL) If solution were cooled to 0°C, how many grams of R would crystallize out? (report to one decimal place) (Show calculations)

2) You dissolve an amount of solid Q in 195.0 mL solvent, forming an unsaturated solution. The solubility of Q at 0°C is 0.87 g/100 mL. The amount of solid remaining in solution at 0°C is 13.0% of the original amount of solid dissolved. What is the original amount of solid that was dissolved (report to 1 decimal place)?

3) What can one do to obtain a second crop of crystals after initial crystals have been collected? What is the drawback of this method?

4) If you are using a trial-and-error method to pick a solvent for recrystallization, why would it be advisable to try low-boiling solvents first, especially if you have a limited sample of solid that you wish to recrystallize?

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