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What is the primary function of solvent extraction in analytical chemistry?
What is the primary function of solvent extraction in analytical chemistry?
Diethyl ether and benzene are examples of solvents that are denser than water.
Diethyl ether and benzene are examples of solvents that are denser than water.
False
What type of chromatography is most commonly used in organic analytical chemistry?
What type of chromatography is most commonly used in organic analytical chemistry?
Chromatography
In a two-phase mixture, one phase is predominantly ______ and the other phase is predominantly ______.
In a two-phase mixture, one phase is predominantly ______ and the other phase is predominantly ______.
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Which of the following solvents should generally be preferred due to lower toxicity when given a choice?
Which of the following solvents should generally be preferred due to lower toxicity when given a choice?
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The volumes of each phase after mixing in solvent extraction are typically equal to the original volumes mixed.
The volumes of each phase after mixing in solvent extraction are typically equal to the original volumes mixed.
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Name one common use of solvent extraction in analytical chemistry.
Name one common use of solvent extraction in analytical chemistry.
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Match the common solvents to their characteristics:
Match the common solvents to their characteristics:
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What happens to the mass remaining in the solid if the volume of extractant is doubled?
What happens to the mass remaining in the solid if the volume of extractant is doubled?
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Using more solvent in a single extraction is always the most effective method.
Using more solvent in a single extraction is always the most effective method.
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What is one common laboratory method used for isolating or purifying products?
What is one common laboratory method used for isolating or purifying products?
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A separatory funnel is used in the _____ extraction process.
A separatory funnel is used in the _____ extraction process.
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Which of the following is NOT a criterion for an organic solvent used in extraction?
Which of the following is NOT a criterion for an organic solvent used in extraction?
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Match the extraction solvent with its characteristic:
Match the extraction solvent with its characteristic:
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Organic products typically dissolve in the aqueous layer during liquid-liquid extraction.
Organic products typically dissolve in the aqueous layer during liquid-liquid extraction.
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If 4 g of butyric acid is to be extracted from 500 mL of water, what is the volume of ether used for extraction?
If 4 g of butyric acid is to be extracted from 500 mL of water, what is the volume of ether used for extraction?
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What was the total amount of butyric acid extracted after two extractions with 250 mL portions of ether?
What was the total amount of butyric acid extracted after two extractions with 250 mL portions of ether?
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The partition coefficient for the system discussed is 3 at a temperature of 25°C.
The partition coefficient for the system discussed is 3 at a temperature of 25°C.
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How much butyric acid remains in the water phase after five extractions with 100 mL portions of ether?
How much butyric acid remains in the water phase after five extractions with 100 mL portions of ether?
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In an extraction, to convert a base into its protonated form, a ______ pH is desirable.
In an extraction, to convert a base into its protonated form, a ______ pH is desirable.
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Match the following amounts of butyric acid extracted with the corresponding ether portion used:
Match the following amounts of butyric acid extracted with the corresponding ether portion used:
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What does the distribution coefficient, D, depend on in the context provided?
What does the distribution coefficient, D, depend on in the context provided?
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An acid should be extracted into water using a high pH to convert it into HA-.
An acid should be extracted into water using a high pH to convert it into HA-.
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What is the main factor that affects the solubility of an amine in water during extraction?
What is the main factor that affects the solubility of an amine in water during extraction?
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What is a characteristic of a monodentate ligand?
What is a characteristic of a monodentate ligand?
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Most transition metal ions can bind to 4 ligands.
Most transition metal ions can bind to 4 ligands.
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What type of ligand can bind to a metal ion through more than one ligand atom?
What type of ligand can bind to a metal ion through more than one ligand atom?
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The distribution coefficient for metal extraction depends on the pH and the concentration of the __________.
The distribution coefficient for metal extraction depends on the pH and the concentration of the __________.
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Which of the following statements is true about chelating ligands?
Which of the following statements is true about chelating ligands?
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Charged complexes like Fe(EDTA)- are very soluble in organic solvents.
Charged complexes like Fe(EDTA)- are very soluble in organic solvents.
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What happens when a ligand binds to a metal ion?
What happens when a ligand binds to a metal ion?
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Match the following types of ligands with their characteristics:
Match the following types of ligands with their characteristics:
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At which pH can Cu2+ be separated from Pb2+ and Zn2+ using dithizone?
At which pH can Cu2+ be separated from Pb2+ and Zn2+ using dithizone?
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Benzene has a higher boiling point than toluene.
Benzene has a higher boiling point than toluene.
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What is the main purpose of a distillation column?
What is the main purpose of a distillation column?
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The vapour pressure of pure benzene at 20 °C is _____ mm Hg.
The vapour pressure of pure benzene at 20 °C is _____ mm Hg.
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Match the following substances with their boiling points:
Match the following substances with their boiling points:
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Which of the following best describes fractional distillation?
Which of the following best describes fractional distillation?
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The packing material in a distillation column is used to provide cooler surfaces for vapor condensation.
The packing material in a distillation column is used to provide cooler surfaces for vapor condensation.
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What happens to the composition of the vapor when a mixture of benzene and toluene is vaporized?
What happens to the composition of the vapor when a mixture of benzene and toluene is vaporized?
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What is the distillate obtained from fractional distillation of the benzene-toluene mixture?
What is the distillate obtained from fractional distillation of the benzene-toluene mixture?
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Toluene is the distillate obtained from fractional distillation of a benzene-toluene mixture.
Toluene is the distillate obtained from fractional distillation of a benzene-toluene mixture.
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What is the boiling point of benzene?
What is the boiling point of benzene?
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The vapour that comes out of the top of the column is called the ______.
The vapour that comes out of the top of the column is called the ______.
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At what temperature does a benzene-toluene solution with $x_{benz} = 0.30$ boil?
At what temperature does a benzene-toluene solution with $x_{benz} = 0.30$ boil?
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Match the following components from the fractional distillation process:
Match the following components from the fractional distillation process:
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The vapour becomes progressively richer in toluene after repeated cycles of fractional distillation.
The vapour becomes progressively richer in toluene after repeated cycles of fractional distillation.
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What type of compounds does petroleum primarily consist of?
What type of compounds does petroleum primarily consist of?
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Study Notes
Solvent Extraction
- Solvent extraction is a technique used to transfer desired analytes from one matrix to another.
- This process is often used when the initial matrix (e.g., soil) isn't suitable for standard analytical methods.
- Water is frequently unsuitable for direct use in chemical instruments, thus requiring extraction.
- Extraction involves transferring a solute from one liquid phase to another or from a solid phase to a liquid phase.
- Typically, an aqueous solution is extracted with an organic solvent.
- Common organic solvents include diethyl ether, benzene, chloroform, dichloromethane, and carbon tetrachloride.
- Organic solvents are less dense than water, forming a separate phase.
- Chloroform, dichloromethane, and carbon tetrachloride are denser than water.
- The choice of solvent should prioritize less toxic options.
- A two-phase mixture will have some of each solvent present in both phases, but one phase will be predominantly water and the other organic.
Analytical Separations
- Chemical analyses of samples often require separation of the analyte from interfering substances in the sample.
- Analytical chemistry significantly focuses on achieving these separations.
- Organic analytical chemistry routinely uses chromatography for separations.
- Gas and liquid chromatography are instrumental methods used in separations.
- Solvent extraction is a manual separation technique still used in modern analytical laboratories.
Extraction (Solid-Liquid)
- A weighed solid is placed in a container with a solvent.
- Mixing allows some portion of the solid to dissolve.
- The dissolving material has stronger interactions with the solvent than with the remaining solid, promoting transfer into solution.
- This process isolates the analyte of interest from the remaining part of the solid.
Extraction (Liquid-Liquid)
- A common method for separation.
- Involves two immiscible liquids that don't dissolve into each other.
- Two layers form after mixing, and these are separated by draining one layer.
- Organic product isolation from inorganic substances uses liquid-liquid extraction.
Solvent Extraction - Criteria
- The organic solvent used in extraction needs to dissolve the substance readily.
- The solvent should not chemically react with the substance extracted.
- The solvent should not mix with water (this is usually the second solvent used).
- It must have a low boiling point.
Solvent Extraction - Examples
- A solvent extraction of butyric acid involves 4 grams of butyric acid from 500 mL of water. Solvent used in extraction is ether with an extraction coefficient (K) of 3.
- Single batch - 3 grams extracted to the ether layer, leaving 1 gram in water layer.
- Two succesive extractions, each with 250 mL portion - 2.4 gram is extracted to the ether phase, leaving 1.6 gram in the water phase.
pH Effects
- Solvent extraction of an amine depends on pH as well.
- The equilibrium constant for the extraction process that uses a base needs to be taken into account.
Chelating Ligands
- Metal ions are considered Lewis acids, which can accommodate electron pairs donated by the ligand.
- Cyanide (CN) is considered a "monodentate" ligand that binds to a metal ion through a single atom.
- Chelating ligands bind through more than one atom to form a complex with the metal ion. This allows for separation by reacting with different metal ions and creating selective extraction.
- Dithizone, 8-Hydroxyquinoline (oxine), and Cupferron are common chelating ligands used for metal ion separation.
Extraction with a Metal Chelator
- A scheme used for separating metal ions involves forming complexes with an organic ligand.
- The metal-ligand complex is then extracted into an organic solvent.
Metal Chelators (further details)
- The ligands work as weak acids and lose a proton when they bind to a metal ion.
- Most complexes that can be extracted into organic solvents must be neutral.
- Many of the formed charged complexes are not soluble in organic solvents.
Metal Chelators (Distribution Coefficient)
- An equation for the distribution coefficient of a metal between the two phases can be derived.
- It is assumed that essentially all of the metal in the aqueous phase is in the form Mn+ and all of the metal in the organic phase is in the form MLn.
- The partition coefficients for the ligand and the complex are defined.
- The distribution coefficient (D) is defined as: D = [total metal]org/ [total metal]aq
Fractional Distillation
- Separation of components from a liquid mixture via fractional distillation.
- The more volatile component leaves the mixture first at higher temperatures.
- The process repeats until a pure component is extracted. A column with packing material is used to create many sequential vaporization and condensation steps that improves purity of the distillate (more volatile phase).
- The remaining component is called residue and is less volatile than the more volatile component. Components are extracted from a mixture based on boiling point differences.
- Involves many repetitions of vaporization and condensation.
- Useful in separating mixtures of similar boiling points (i.e., benzene-toluene mixture).
Distillation of Petroleum
- Petroleum (crude oil) is a mixture of alkanes, other elements, and organic compounds.
- It is separated into different fractions through distillation in a distillation column.
- Gasoline, kerosene, diesel fuel, and other petroleum fractions obtained are extracted from petroleum in a refining process based on differing boiling points.
Liquid-Vapour Equilibrium
- A graph depicting the relation between vapor and liquid compositions in a binary mixture (e.g. benzene-toluene mixture).
- The graph is useful in explaining how fractional distillation works.
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Description
Test your knowledge on the principles and applications of solvent extraction in analytical chemistry. This quiz covers various solvents, chromatography methods, and specific characteristics relevant to organic chemistry techniques. Challenge yourself to see how well you understand the processes involved in solvent extraction.
