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
- A mixture of the two compounds shown below is dissolved in ether. Using the information given in the experiment, select all the correct statements regarding the extraction and isolation of the two compounds. HN ostan OH X Y A. X can precipitate if hydrochloric acid is added to the salt of X in the aqueous layer. B. Y can precipitate if hydrochloric acid is added to the salt of Y in the aqueous layer. C. X can be extracted from the organic layer using hydrochloric acid. D. Y can be extracted from the organic layer using hydrochloric acid.arrow_forward4. Suppose you have a mixture of saturated aqueous sodium chloride (brine) and your 2-bromo-2-methylbutane product in a separatory funnel. Use densities to predict which phase will be the top layer in the funnel. a. 2-bromo-2-methylbutane (organic phase) b. saturated sodium chloride (aqueous phase) c. hard to predict since densities are both very close to 1.18 g/mL d. there would only be one phase since the substances are misciblearrow_forwardwhich of the following statements regarding purification by recrystallization is false? i. activated charcoal removes insoluble impurities. ii. water is the best recrystallization solvent for organic compounds. iii. slow cooling permits the exclusion of the solvent from the recrystallized solid. a. i, ii, and iii b. i and ii c. i only d. ii and iiiarrow_forward
- 1. Explain the importance of using a thermometer in the simple distillation setup. 2. Enumerate the characteristics of a substance for it to be separated from the heterogeneous mixture by steam distillation. 3. How does steam facilitate the distillation of essential oils? 4. Discuss some applications of simple distillation and steam distillation. Explain why you can use each method for the chosen application.arrow_forwardA mixture of the two compounds shown below is dissolved in ether. Using the information given in the experiment, select all the correct statements regarding the extraction and isolation of the two compounds. oja OH X Y QA. Y can be extracted from the organic layer using sodium hydroxide. OB. X can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of X. OC. X can be extracted from the organic layer using sodium hydroxide. OD. Y can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of Y.arrow_forwardA mixture of the two compounds shown below is dissolved in ether. Using the information given in the experiment, select all the correct statements regarding the extraction and isolation of the two compounds. X ОН Y A. X can be extracted from the organic layer using sodium hydroxide. B. Y can be extracted from the organic layer using sodium hydroxide. C. Y can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of Y. D. X can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of X.arrow_forward
- Why can we use a water-ethanol mixture but not a water-hexane mixture as a recrystallization solventarrow_forward1. Explain the importance of using a thermometer in the simple distillation setup. 2. Enumerate the characteristics of a substance for it to be separated from the heterogeneous mixture by steam distillation. 3. How does steam facilitate the distillation of essential oils? 4. Discuss some applications of simple distillation and steam distillation. Explain why you can use each method for the chosen application. 5. What is the most dominant intermolecular forces of attraction that exist between: a. water and limonene, the major monoterpene component of lemon essential oil? b. water and constituent ions of sodium chloride? 6. Based on your answers in number 5, which pair (water-limonene or water-sodium chloride) exhibits a stronger attraction between their molecules/ions? 7. Describe what happens during the salting-out process in terms of the intermolecular forces of attraction involved as mentioned in your previous answers.arrow_forwardIn which of the following cases would recrystallization be favored over extraction when purifying a mixture of two solid compounds? I. When a significant difference in pKa exists between the two compounds. II. When both compounds have the same functional group(s). III. When the desired compound is poorly soluble in the solvent pair at low temperatures and greatly soluble in the solvent pair at high temperatures. A. I and III B. II C. II and III D. I and II E. I, II, and III F. None of the abovearrow_forward
- For the following reactions, draw arrow-pushing mechanisms for each of the reactions that (a) extracted them into the aqueous layer and (b) forced them to precipitate out. Acidic compound precipitated after the addition of HCl.arrow_forwardWhich of these is NOT true of a good recrystallization solvent? Which of these is NOT true of a good recrystallization solvent? a) The compound is insoluble in the solvent when it is cold. b) The solvent boiling temperature is at least 40 °C. c) The solvent has many impurities. d) The compound is soluble in the solvent when it is hot.arrow_forwardYou have learned three different types of distillation (simple, fractional, steam). For each case below, explain which type of distillation would be most efficient in terms of time and separation. A. Separating 1-butanol from its constitutional isomer 2-butanol B. Separating limonene from lemon peel C. Separating ethanol from ethylene glycolarrow_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