a)
Interpretation:Most suitable solvent for recrystallization of impure solids should be determined. Also, reason for the same should be determined.
Concept introduction:Criteria mentioned below should be used to select solvent for recrystallization.
1. Solvent should be able to dissolve desired compound in itself at high temperatures but insoluble at low temperatures. In short, solvent with favorable temperature coefficient should be used for particular solute.
2. Solvent should be chosen in such way that impurities are either insoluble in it or remain moderately soluble in it at low temperatures.
3. Boiling point of desired solvent should be low so that it gets separated from crystals easily.
4. Boiling point of solvent should be less than melting point of solid under consideration.
5. There should be no reaction between solvent and substance that needs to be purified.
b)
Interpretation:Reason for ethanol and petroleum ether not to be used as suitable solvent for recrystallization should be determined.
Concept introduction:Criteria mentioned below should be used to select solvent for recrystallization.
1. Solvent should be able to dissolve desired compound in itself at high temperatures but insoluble at low temperatures. In short, solvent with favorable temperature coefficient should be used for particular solute.
2. Solvent should be chosen in such way that impurities are either insoluble in it or remain moderately soluble in it at low temperatures.
3. Boiling point of desired solvent should be low so that it gets separated from crystals easily.
4. Boiling point of solvent should be less than melting point of solid under consideration.
5. There should be no reaction between solvent and substance that needs to be purified.
c)
Interpretation:Chemical structures for water, ethanol, toluene, petroleum ether,
Concept introduction:Solvent for recrystallization process should be selected in such way that solute particles remain undissolved in solvent at low temperatures but become soluble at high temperatures. It should be chosen in such way that impurities are either insoluble in it or remain moderately soluble in it at low temperatures.Boiling point of desired solvent should be low so that it gets separated from crystals easily. Boiling point of solvent should be less than melting point of solid under consideration. No reaction should occur between solvent and substance that needs to be purified.
d)
Interpretation:Most polar and least polar solvents among water, ethanol, toluene, petroleum ether,
Concept introduction:Polar solvents have dipole moment in them while there is no dipole moment in nonpolar solvents. Hexane, benzene, carbon tetrachloride are examples of nonpolar compounds whereas ammonia, water, hydrogen fluoride are polar solvents.
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Chapter 3 Solutions
EBK EXPERIMENTAL ORGANIC CHEMISTRY: A M
- Which of the three methods, (Use of Separatory Funnel, Decantation or Use of Pasteur Pipette) do you believe is most suitable for transferring large volumes of liquid mixtures and why?arrow_forwardAn organic chemistry laboratory Extraction; the extraction of crude naphtalene- benzoic acid mixture. Naphthalene is a suspect carcinogen and is toxic to aquatic life. Find an alternative pair of molecules that adhere better to the principles of green chemistry and can be separated by extraction using green' solvents. (kindly answer fully)arrow_forwardWhen a pure sample of tert-butyl bromide is analyzed by gas chromatography, two components are usually observed. One of them is tert-butyl bromide and the other one is a decomposition product. As the temperature of the injector is increased, the amount of the decomposition product increases and the amount of tert-butyl bromide decreases.a. What is the structure of the decomposition product?b. Why does the amount of decomposition increase with increasing temperature?c. Why does tert-butyl bromide decompose much more easily than tert-butyl chloride?arrow_forward
- Given the following statements, which would be the ideal solvent to use for recrystallization of this compound? Why? Compound X is soluble in both cold ethyl acetate and hot ethyl acetate. Compound X is insoluble in cold benzene but soluble in hot benzene. Compound X is insoluble in both cold hexanes and hot hexanes. Compound X is insoluble in cold ethanol but soluble in hot ethanol.arrow_forwardExplain and elaborate how the following purification techniques work: a. Sublimation b. Recrystallizationarrow_forwardFor either of these solvents explain why it would be a better choice as a recrystallization solvent than the other (water vs. ethanol).arrow_forward
- In an experiment the essential oils from herbs, were extracted with water. Explain how you will separate the oils from the water using liquid-liquid extraction. Discuss the procedure, equipment and extraction solvent choicearrow_forwardWhy would a solvent with a very high boiling point be inappropriate for a recrystallization? Too much solvent would be lost to evaporation during the heating phase of the recrystallization Impurities and the compound to be recrystallized would dissolve equally well in this solvent A high boiling solvent would not dissolve the compound to be recrystallized It would be difficult to remove residual solvent from the purified crystalsarrow_forwarda student performed a recrystallization on 515 mg of impure compound using ethanol. After isolating the crystals, he obtained only 215 mg of pure product. Knowing that his sample was only slightly impure, he concluded that a significant amount of product was lost. Explain what likely happened and what he can do to recover his product.arrow_forward
- Explain through a laboratory experiment: How is recrystallization of Acetone possible? Can it or how would it be carried out if yes?arrow_forwardPropose an efficient separation and recovery scheme for a mixture of toluene, benzoic acid, andaniline. Consider that steam distillation is not an option.arrow_forwardA student recrystallized some impure benzoic acid and isolated it by filtration. He scraped the purified benzoic acid off the filter paper after it had dried and took the melting point as a test for purity. He was surprised that most of the white solid melted sharply between 121 and 122 °C but that a small amount remained unmelted even at temperatures above 200 °C. Explain this behavior.arrow_forward
- EBK A SMALL SCALE APPROACH TO ORGANIC LChemistryISBN:9781305446021Author:LampmanPublisher:CENGAGE LEARNING - CONSIGNMENTMacroscale and Microscale Organic ExperimentsChemistryISBN:9781305577190Author:Kenneth L. Williamson, Katherine M. MastersPublisher:Brooks Cole