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Questions and Answers
What is the primary purpose of solvent extraction in the experiments conducted?
What is the primary purpose of solvent extraction in the experiments conducted?
- To dissolve the samples for observation.
- To extract pigments from the samples.
- To analyze the physical properties of the solvents used.
- To measure the % yield and determine partition coefficient (Kp). (correct)
Which of the following is NOT a method of solvent extraction discussed in the experiments?
Which of the following is NOT a method of solvent extraction discussed in the experiments?
- Liquid-liquid extraction
- Solid-liquid extraction
- Gas-liquid extraction (correct)
- Liquid-solid extraction
Which solvent was specifically mentioned for dissolving samples in Experiment 1?
Which solvent was specifically mentioned for dissolving samples in Experiment 1?
- Diethyl Ether
- EtAc (correct)
- Acetone
- Ethanol
In the context of solid-liquid extraction, which of the following is a correct example?
In the context of solid-liquid extraction, which of the following is a correct example?
What observation was likely expected after dissolving samples in both H2O and EtOH?
What observation was likely expected after dissolving samples in both H2O and EtOH?
What are emulsions primarily composed of?
What are emulsions primarily composed of?
What condition is necessary for the extraction and solution solvent in solvent extraction?
What condition is necessary for the extraction and solution solvent in solvent extraction?
What is the role of detergents in an emulsion?
What is the role of detergents in an emulsion?
What issue does 'salting out' address in solvent extraction?
What issue does 'salting out' address in solvent extraction?
Which of the following is NOT a requirement for an extraction solvent?
Which of the following is NOT a requirement for an extraction solvent?
How can one visualize the interface when it cannot be seen due to dark layers?
How can one visualize the interface when it cannot be seen due to dark layers?
Which of the following solvents has a higher density based on the given data?
Which of the following solvents has a higher density based on the given data?
What does the Beer-Lambert Law express?
What does the Beer-Lambert Law express?
Why is a quartz cuvette preferred over other materials for measuring absorbance?
Why is a quartz cuvette preferred over other materials for measuring absorbance?
What role does dark incubation play in pigment extraction?
What role does dark incubation play in pigment extraction?
What is the order of solubility of salicylic acid from highest to lowest in various solvents?
What is the order of solubility of salicylic acid from highest to lowest in various solvents?
What unit is used to express molar absorptivity in the content?
What unit is used to express molar absorptivity in the content?
If a compound has an absorbance of 1.35 in a 10-mm cuvette, what might be inferred about its concentration?
If a compound has an absorbance of 1.35 in a 10-mm cuvette, what might be inferred about its concentration?
Among the solvents listed, which has the highest boiling point?
Among the solvents listed, which has the highest boiling point?
Which solvent has a reported miscibility with water?
Which solvent has a reported miscibility with water?
What is the purpose of using acetone, methanol, and ethanol in pigment extraction?
What is the purpose of using acetone, methanol, and ethanol in pigment extraction?
What effect does cohesive energy have on the solubility of salicylic acid?
What effect does cohesive energy have on the solubility of salicylic acid?
What information is conveyed by the unique wavelength (wv) of a compound's absorbance?
What information is conveyed by the unique wavelength (wv) of a compound's absorbance?
How is pigment concentration determined after absorbance measurement?
How is pigment concentration determined after absorbance measurement?
At what temperature is the solubility of salicylic acid least in water?
At what temperature is the solubility of salicylic acid least in water?
What is the solubility of salicylic acid in carbon tetrachloride (CCl4) at 25°C?
What is the solubility of salicylic acid in carbon tetrachloride (CCl4) at 25°C?
Which of the following statements about xylene is correct?
Which of the following statements about xylene is correct?
What form does salicylic acid crystallize into after heating?
What form does salicylic acid crystallize into after heating?
What are the two general steps conducted in the microscale extraction process?
What are the two general steps conducted in the microscale extraction process?
What is the role of the solvents used in the extraction process?
What is the role of the solvents used in the extraction process?
What type of mixtures are formed during the solvent extraction process?
What type of mixtures are formed during the solvent extraction process?
Which of the following solvents is typically used in extraction due to its low density?
Which of the following solvents is typically used in extraction due to its low density?
How are solutes like SA, BA, and sucrose characterized in the extraction process?
How are solutes like SA, BA, and sucrose characterized in the extraction process?
What is typically determined after conducting the extraction process?
What is typically determined after conducting the extraction process?
Why is the density of extraction solvents important?
Why is the density of extraction solvents important?
What happens to the solutes after extraction in the process?
What happens to the solutes after extraction in the process?
Study Notes
Experiments Overview
- Experiment 1 focused on solvent extraction techniques.
- Experiment 2 examined pigment extraction methods.
Solvent Extraction
- Extraction Defined: Process of separating a substance from a mixture based on its different solubility in two immiscible liquids.
- Liquid-Liquid Extraction: Involves separating compounds dissolved in two different liquids, e.g., using dichloromethane (DCM) and water.
- Solid-Liquid Extraction: Involves extracting substances from solid matrices into liquids, e.g., coffee extraction with hot water.
Key Compounds Used
- Salicylic Acid (HOC₆H₄COOH)
- Benzoic Acid (C₆H₅COOH)
- Sucrose (C₁₂H₂₂O₁₁) splits into glucose and fructose upon hydrolysis.
Extraction Methodology
- Samples dissolved in a combination of water and ethanol (EtOH).
- Utilize ethyl acetate (EtAC) and DCM for separation.
- Monitoring extraction involves calculating % yield and distribution coefficients (Kp).
Observations in Extraction
- Aqueous and organic layers exhibit clear separation post-extraction.
- Two steps: mixing immiscible liquids and separating resulting layers.
Solubility Insights
- Solubility of salicylic acid decreases in this order: Ethanol > Ethyl Acetate > Carbon Tetrachloride > Xylene > Water.
- High boiling points and cohesive energies of solvents affect their solubility characteristics.
Density of Solvents
- Density impacts separation efficiency of organic extracts.
- Ethyl acetate has a lower density (0.90 g/mL) compared to DCM (1.33 g/mL).
Troubleshooting Extraction
- Emulsions may form, complicating separation. Strategies include “salting out” to enhance separation.
- Dark layers can obscure visual identification of interfaces; use of light or funnel tilting aids in clarity.
Considerations for Effective Extraction
- Immiscibility between extraction and solution solvents is crucial.
- Extraction solvent should possess a high distribution coefficient (Kp) to favor the target component.
- Ideal solvents should be easily separable, low in toxicity, and cost-effective.
Pigment Extraction
- Conducted using acetone, methanol, and ethanol for sample preparation.
- Absorbance measured via spectrophotometry; Beer-Lambert Law relates absorbance to concentration.
Key Calculation in Pigment Extraction
- Example provided for determining molar absorptivity from absorbance data.
- Absorbance (A) of 1.35 at 750 nm in a 10-mm cuvette requires application of the Beer-Lambert Law for calculations.
Pigment Measurement
- Spectrophotometer measures light intensity absorbed by solutions, crucial for assessing pigment concentrations.
Conclusion
- Vital techniques in extraction methods include proper solvent selection, solubility understanding, and analytical measurements to ensure efficient and accurate outcomes in both experiments.
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Description
This quiz focuses on the post-laboratory discussions of two experiments: solvent extraction and pigment extraction. You will define key concepts and examples related to liquid-liquid and solid-liquid extraction methods. Test your understanding of these fundamental chemistry techniques.
