what alcohol(s) could be used to produce each of the following compounds?

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A chemist carries out a reaction that generates several side products. Which of the post-obit can she eliminate from the reaction mixture by washing with an aqueous solution of sodium hydroxide?

Possible Answers:

I, II, III, and Four

III and Four

I only

I and III

I, Three, and Four

Explanation:

In organic chemistry, chemists oftentimes exploit the acidic and basic properties of side products in guild to remove them. Compounds I-4 are all organic-soluble, however, if they are converted to a sodium common salt via deprotonation with sodium hydroxide, they volition become fully soluble in the aqueous sodium hydroxide solution and be washed away with this layer. The question we must so address is which of these iv compounds will be deprotonated by sodium hydroxide.

Sodium hydroxide is a relatively potent base. Given its conjugate acrid is h2o, which has a pKa of 15.vii, sodium hydroxide can deprotonate any compound with a pka lower than xv.7. Another way to say this is that sodium hydroxide has a pkaH (divers equally the pKa of the conjugate acid) of fifteen.7. Thus, we run across that I and Three may be deprotonated and washed abroad, leaving II and 4 behind in the reaction mixture.

Which of the following compounds has the highest boiling signal?

Possible Answers:

2-methyl-2-propanol

i,ii-ethanediol

two-methyl-2,4-pentanediol

2-methyl-2-butanol

Hexanol

Correct reply:

2-methyl-2,4-pentanediol

Caption:

There are a few rules to follow when estimating the boiling point of certain compounds. One dominion is that the more carbons there are, the college the humid bespeak. However, hydrocarbon molecules merely showroom Van der Waals forces (the weakest intermolecular force).

The reason 2-methyl-2,iv-pentanediol is right is because it has two -OH groups that are capable of hydrogen bonding (the strongest intermolecular force). This chemical compound besides has a significant number of carbons compared to the other compounds. Combined, these factors will each raise the boining bespeak of the compound.

Suppose that a chemistry student wants to split a mixture consisting of benzoic acid, napthalene, and due north-butylamine dissolved in ether. Kickoff, the student adds an aqueous solution of to the mixture so extracts the aqueous layer to give solution A. Side by side, the student adds an aqueous solution of to the mixture and so extracts the aqueous layer to give solution B. The remaining organic phase of the mixture is assigned equally solution C.

Which of the post-obit gives the correct consignment of the contents of solutions A, B, and C?

Possible Answers:

Solution A contains northward-butylamine, Solution B contains benzoic acid, and Solution C contains napthalene

Solution A contains napthalene, Solution B contains n-butylamine, and Solution C contains benzoic acid

Solution A contains napthalene, Solution B contains benzoic acrid, and Solution C contains n-butylamine

Solution A contains benzoic acrid, Solution B contains n-butylamine, and Solution C contains napthalene

Correct answer:

Solution A contains due north-butylamine, Solution B contains benzoic acid, and Solution C contains napthalene

Explanation:

This question is giving united states of america a scenario in which a mixture of organic compounds is beingness separated via extraction. When doing extractions, the chemist is able to take reward of the fact that organic compounds can be plant in one of 2 layers: either the aqueous layer or the organic layer. The aqueous layer will incorporate molecules that are hydrophilic or that possess a internet charge, while the organic layer will comprise molecules that are hydrophobic and exercise not possess a charge.

Initially, all three compounds are dissolved in a solution of ether. From this, nosotros tin can infer that the three compounds are starting off every bit being relatively hydrophobic and with no internet charges.

The beginning solution to be added is aqueous. Upon calculation this, we will have two layers - 1 aqueous and i organic. Since we know that this is a stiff acid, we can await that the due north-butylamine that is dissolved in the ether to become protonated (since it will deed as a base of operations). Furthermore, since the protonated north-butylamine now carries a net positive charge, it volition be expected to transfer from the organic phase into the aqueous phase. Removal of the aqueous layer in this case gives us Solution A, which contains n-butylamine.

Next, nosotros are told that an aqueous solution of is added to the mixture. But as earlier, adding this solution results in a scenario where nosotros have an organic phase and an aqueous phase. Since we know that is a stiff base, we can look the benzoic acrid in the organic phase to become deprotonated. Upon deprotonation, benzoate now carries a cyberspace negative charge, making it more favorable for it to movement over and dissolve within the aqueous layer. Therefore, Solution B will incorporate benzoic acid.

And lastly, the remaining organic phase, which we phone call Solution C, will nevertheless contain napthalene because information technology was never able to cross over to any of the aqueous layers, attributable to its hydrophobic nature.

During partial distillation, substances are separated according to which of the post-obit characteristics?

Possible Answers:

Molecular weight

Boiling points

Molarities

Melting points

Right reply:

Humid points

Explanation:

The process of fractional distillation separates an organic mixture containing different hydrocarbons by heating them in long, insulated copper columns until they vaporize. Therefore, the hydrocarbons are separated according to their humid points-compounds with lower boiling points volition exist separated first and compounds with college humid points volition be separated last.

Which of the following laboratory procedures could best be used to split up benzoic acrid from phenol if they are both solvated in hexanes?

Possible Answers:

Extraction using sodium hydroxide

Fractional distillation

Distillation

Extraction using sodium bicarbonate

Recrystallization

Correct answer:

Extraction using sodium bicarbonate

Explanation:

Extraction with sodium bicarbonate is correct considering it will deprotonate benzoic acid and non phenol, which will permit benzoic acid to enter the aqueous layer while leaving about of the phenol in the organic layer. Once extracted, benzoic acid can be farther isolated by other laboratory techniques. Sodium hydroxide would deprotonate both benzoic acrid and phenol, and thus would not effectively seperate them. Since both phenol and benzoic acid accept melting points above hexane's boiling signal, whatever form of distillation will non work for isolating benzoic acid. Recrystallization volition also not work, as the solubilities of benzoic acrid and phenol are similar.

When is fractional distillation used?

Possible Answers:

When attempting to separate two mixtures whose boiling points are similar

When attempting to carve up ii mixtures whose boiling points are very low

When attempting to split two mixtures whose humid points are very different

When attempting to separate two mixtures whose humid points are very high

Correct answer:

When attempting to carve up two mixtures whose humid points are similar

Explanation:

Distillation is used to identify and purify organic compounds. In the procedure of purification, we divide a chemical compound from another textile by exploiting their boiling points. When unlike compounds in a mixture have different boiling points, the mixture separates into its component parts when information technology is distilled.

A simple distillation apparatus contains a round-bottom flask attached to an adapter holding a thermometer (to determine the boiling signal of the liquid). The adapter connects to a condenser into which cold water passes through. The condenser leads to a collection flask for the pure liquid. Elementary distillations are used when the liquid is already relatively pure, when the liquid has a non-volatile component (like a solid contaminant), and when the liquid is contaminated by a liquid with a boiling point that differs by at least ° Celsius (when the boiling points are very different).

A fractional distillation apparatus is basically the same every bit the elementary distillation appliance, but in the former, a fractionating column is placed between the boiling flask and the condenser. Fractional distillation is used when trying to separate liquids whose boiling points differ by less than ° Celsius--when attempting to divide liquids whose humid points are similar.

Vacuum distillation is distillation at a lower pressure. As the boiling point of a compound is lower at a lower external pressure, the compound will non have to be heated as much equally information technology normally would in order for it to brainstorm boiling. Vacuum distillation is used to distill compounds that accept a high humid indicate (over ° Celsius), or whatever other compound which may decompose upon heating at atmospheric pressure.

The following oxidation of benzyl alcohol to benzoic acid was performed. It was determined that 13% of the alcohol was unreacted after the reaction. What purification method would you lot use to all-time divide the two compounds?

Possible Answers:

Acid-base extraction

Fractional distillation

Filtration

Infrared spectroscopy

Column chromtagraphy

Correct reply:

Acid-base of operations extraction

Explanation:

The 2 compounds would exist separated very quickly and easily by acrid-base extraction, using minimal solvent. Cavalcade chromatography uses large quantities of solvent and is not very suitable for very polar compounds, such as carboxylic acids. Fractional distillation does not work very well for compounds with high boiling points such as benzoic acid . Filtration just works when 1 compound is soluble in a solvent that the other is insoluble. These two compounds take almost identical solubility. IR spectroscopy is an identification technique, not a separation technique.

The acid-base of operations extraction uses a base of operations such as aqueous bicarbonate to convert the carboxylic acid into a water soluble table salt (carboxylate). The booze is unaffected by this weak base  and stays in the organic solvent layer. The water layer is separated so acidified to recover the pure carboxylic acrid.

A reaction is run to form a compound that has a humid signal of . Assume there is 13% starting material unreacted that has a boiling signal of , what is the best method to purify the product?

Possible Answers:

Vacuum distillation

Micro distillation

None of these

Elementary distillation

Fractional distillation

Correct answer:

Fractional distillation

Explanation:

The rule of pollex is if the compounds accept a boiling signal departure of less than  you lot use partial distillation. Simple distillation is only used to divide solids from liquids or liquids from liquids that take a large boiling bespeak difference . Vacuum distillation is only used for compounds with a very loftier humid points . Vacuum is applied that volition reduce the force per unit area closer to the compounds vapor pressure level (and is non considered very efficient separating compounds with close boiling points). Micro distillation is a special technique used to separate compound mixtures .

Recrystallization is a technique used to purify solid compounds, which involves growing crystals. The compound you are recrystallizing should have which of the following solubilities in the recrystallization solvent:?

Possible Answers:

Insoluble hot; soluble common cold.

Nonpolar soluble; polar insoluble.

Polar soluble; nonpolar insoluble.

Acrid soluble; base insoluble.

Soluble hot; insoluble cold.

Correct answer:

Soluble hot; insoluble cold.

Caption:

There is only i platonic feature of a recrystallization solvent: to dissolve the chemical compound when hot and the compound should be insoluble cold. The technique uses a minimum amount of solvent to deliquesce the chemical compound existence purified at or about the boiling point. The resulting solution is immune to cool, which decreases the solubility. The chemical compound begins to grow crystals, every bit the lattice excludes impurities resulting in a pure compound.

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