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Questions and Answers
What is one key characteristic of Discontinuous Countercurrent Distribution in solvent extraction?
What is one key characteristic of Discontinuous Countercurrent Distribution in solvent extraction?
Which method is primarily used for quantitative separation in analytical chemistry?
Which method is primarily used for quantitative separation in analytical chemistry?
When designing extraction apparatus, which factor is least likely to influence the efficiency of solvent extraction?
When designing extraction apparatus, which factor is least likely to influence the efficiency of solvent extraction?
In which area is solvent extraction particularly advantageous?
In which area is solvent extraction particularly advantageous?
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What is a major limitation of solvent extraction when applied in biochemistry?
What is a major limitation of solvent extraction when applied in biochemistry?
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What is the primary purpose of solvent extraction in analytical chemistry?
What is the primary purpose of solvent extraction in analytical chemistry?
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Which statement best describes the role of the Craig counter-current distribution apparatus?
Which statement best describes the role of the Craig counter-current distribution apparatus?
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What effect does an increase in the number of equilibrations have on solute distribution in counter-current extraction?
What effect does an increase in the number of equilibrations have on solute distribution in counter-current extraction?
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Which of the following is NOT a common application of solvent extraction?
Which of the following is NOT a common application of solvent extraction?
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In solvent extraction, which factor is critical for achieving selectivity in metal extraction?
In solvent extraction, which factor is critical for achieving selectivity in metal extraction?
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Which type of solvent extraction technique is more efficient in isolating metallic components?
Which type of solvent extraction technique is more efficient in isolating metallic components?
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What is one limitation of solvent extraction when dealing with organic compounds?
What is one limitation of solvent extraction when dealing with organic compounds?
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Why are metals considered minor and trace constituents important in the context of solvent extraction?
Why are metals considered minor and trace constituents important in the context of solvent extraction?
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What is the primary purpose of the mobile phase in the extraction process?
What is the primary purpose of the mobile phase in the extraction process?
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In Discontinuous Countercurrent Distribution, how does increasing the number of extractions (n) affect solute separation?
In Discontinuous Countercurrent Distribution, how does increasing the number of extractions (n) affect solute separation?
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What does the coefficient D represent in the context of solute extraction?
What does the coefficient D represent in the context of solute extraction?
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Which of the following statements about quantitative separation in solvent extraction is true?
Which of the following statements about quantitative separation in solvent extraction is true?
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Which method is often more convenient than the lengthy procedure of solvent extraction?
Which method is often more convenient than the lengthy procedure of solvent extraction?
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What type of curve does the distribution of solute between extraction units approach as the number of extractions increases?
What type of curve does the distribution of solute between extraction units approach as the number of extractions increases?
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What type of materials can be separated using the method discussed?
What type of materials can be separated using the method discussed?
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When applying the extraction process, what happens to the portions of the lighter phase?
When applying the extraction process, what happens to the portions of the lighter phase?
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Study Notes
Solvent Extraction
- Solvent extraction is a method that separates chemical substances in a mixture or solution.
- It achieves this by transferring a specific component from one liquid phase to another based on its solubility.
- The process targets retrieving one or more desired constituents from a mixture.
- It's also useful for mixture purification and removing interfering elements.
Types of Mixtures
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Solid in Liquid Mixtures
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Homogenous: Components uniformly distributed
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Evaporation: Removing solvent through heating
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Distillation: Separating components by boiling point differences
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Centrifugation: Separating components by density differences
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Heterogenous: Components unevenly distributed
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Sedimentation/Gravitation: Separation based on density differences
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Filtration: Separating solids from liquids
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Magnetic Separation: Separating magnetic components
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Fractional Distillation: Separating miscible liquids using a more effective distillation technique
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Liquid in Liquid Mixtures
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Homogenous: Components uniformly distributed
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Simple/Fractional Distillation: As described in homogenous solid-liquid mixtures, this involves heating and condensing liquid(s) based on differing boiling points
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Chromatography
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Electrophoresis
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Heterogenous: Components unevenly distributed
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Partitioning: Separating components through separation funnels
Solvent Extraction Process
- A process for separating compounds based on their differing solubilities in different liquids.
- Relevant properties of compounds impacting solubility include polarity, size, mass, density as well as chemical similarities and differences
Quality Considerations
- Quality of the extracted material is essential in many industries, including:
- Mining
- Food processing
- Research labs
Solvent Extraction Example
- Separation of Benzoic acid and p-methoxyphenol.
- The process involves:
- Mixing the mixture in a separating funnel.
- Adding saturated sodium bicarbonate solution.
- Shaking and equilibrating the funnel.
Aqueous Solvents
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Factors to consider when choosing aqueous solvents:
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Purity
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Suitable additives to improve the desired characteristics
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Ensuring the analyte becomes less hydrophilic and more hydrophobic through dissolution
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Different solvents (acids, bases, high-ionic strength solutions, complexing/ion-pairing/chiral agents) needed for various purposes
Organic Solvents
- Factors to consider when choosing organic solvents:
- Immiscibility: Unmixable with water and other solvents
- Density
- Volatility
- Toxicity
- Polarity: matching desired component/s
- Cost
Solvent Extraction Theory
- Solvent extraction is based on the selective transfer of solute.
- The extraction process relies on the differential solubility of components in the different phases.
- Distribution/partition coefficients (KD) are key parameters determining the equilibrium distribution of the solute between two immiscible phases.
- The process is governed by the Nernst partition law
Extraction Efficiency
- Efficiency depends on the distribution ratio (D) and the relative volumes of the liquid phases.
- Calculations determining the extent of extraction, including multi-stage extractions
- Percentage extraction calculations
Selectivity in Extraction
- Partial extraction of other components alongside the targeted one may occur.
- The separation factor (β) helps determine separation efficiency between components.
Extraction of Uncharged Metal Chelates
- Use of organic solvents to extract uncharged metal chelates.
- The reagent needs to behave as a weak acid.
- The presence of hydrophobic groups reduces the aqueous solubility of the complex.
Extraction of Ion-association Complexes
- Extracting charged components by neutralizing the charge with chelation or by association with other ions.
- Formation of stable complexes essential for achieving extraction.
Methods of Extraction
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Batch Extraction: Simplest method; mixing phases, allowing separation, repeating as needed.
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Continuous Extraction: Recycled solvent, more efficient for smaller distribution ratios, requires more complex apparatus
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Description
This quiz covers the method of solvent extraction, focusing on how it separates chemical substances in mixtures. It includes types of mixtures, methodologies like distillation, and purification techniques. Test your knowledge on this essential chemical process.
