Dr. Sol Vent wants to purify 7.00 g of X, which is contaminated with small amounts of Y and Z. He uses crystallization. a) Which solvent should he use, heptane or 1-propanol? Why? Hint: Refer to the page about Recrystallization you read last week, or rewatch the beginning of the Crystallization video. b) Calculate how much of this solvent he should use. Show how you got your answer. Hint: the table above gives the solubility per 100 mL. He doesn't necessarily want to crystallize the grams shown in the table. Maybe he can use proportionally less solvent. c) In which of the six steps listed under "Principles" would he get rid of the Y? Z? Explain both answers. Hint: refer to the Recrystallization page.
The following questions all are based on the data in this table:
Substance Solvent Temp.,oC Solubility, g per 100 mL
X heptane 20 23.5
X heptane 80 27.0
X 1-propanol 20 0.6
X 1-propanol 80 8.7
Y heptane 20 4.0
Y heptane 80 4.0
Y 1-propanol 20 22.0
Y 1-propanol 80 31.0
Z heptane 20 2.8
Z heptane 80 3.7
Z 1-propanol 20 0.0
Z 1-propanol 80 0.0
Dr. Sol Vent wants to purify 7.00 g of X, which is contaminated with small amounts of Y and Z. He uses crystallization.
a) Which solvent should he use, heptane or 1-propanol? Why? Hint: Refer to the page about Recrystallization you read last week, or rewatch the beginning of the Crystallization video.
b) Calculate how much of this solvent he should use. Show how you got your answer. Hint: the table above gives the solubility per 100 mL. He doesn't necessarily want to crystallize the grams shown in the table. Maybe he can use proportionally less solvent.
c) In which of the six steps listed under "Principles" would he get rid of the Y? Z? Explain both answers. Hint: refer to the Recrystallization page.
d) If he cools the solution to 20 oC in step 4, how much X would remain in solution? Show how you got your answer. Hint: refer to the table. If Sol didn't use 100 ml, he may find less X still dissolved in the volume he did use.
e) What would be the maximum possible per cent recovery of X that he could get? Show how you got your answer.
Hint: if some X is still in solution, Sol can't possibly get that back for his product.
As per Bartleby guidelines, first three sub-parts of a question can be answered in one session. If you want any particular part to be solved then please post it as a separate question.
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