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Questions and Answers
Which of the following statements about adsorption chromatography is true?
Which of the following statements about adsorption chromatography is true?
- Polar components move faster than non-polar components.
- It exclusively uses liquid as the mobile phase.
- It operates based on competition between a sample and mobile phase for absorptive sites. (correct)
- It is the most commonly used form of chromatography in laboratories.
Silica Gel is considered a weak adsorbent in chromatography.
Silica Gel is considered a weak adsorbent in chromatography.
False (B)
The ______ is the oldest form of chromatography.
The ______ is the oldest form of chromatography.
adsorption chromatography
Name two properties of a good adsorbent.
Name two properties of a good adsorbent.
Match the following adsorbents with their classifications:
Match the following adsorbents with their classifications:
Which factor influences the strength of an adsorbent?
Which factor influences the strength of an adsorbent?
The greater the rate a zone travels in an elution experiment, the stronger the adsorbent.
The greater the rate a zone travels in an elution experiment, the stronger the adsorbent.
What is the primary basis for separation in partition chromatography?
What is the primary basis for separation in partition chromatography?
Which of the following adsorbents is used in gel filtration chromatography?
Which of the following adsorbents is used in gel filtration chromatography?
Ion-exchange chromatography separates molecules based solely on their molecular size.
Ion-exchange chromatography separates molecules based solely on their molecular size.
What is the purpose of varying pH in ion-exchange chromatography?
What is the purpose of varying pH in ion-exchange chromatography?
Which of the following best describes the process of partition chromatography?
Which of the following best describes the process of partition chromatography?
In cation exchange chromatography, positively charged molecules are attracted to a __________ charged solid support.
In cation exchange chromatography, positively charged molecules are attracted to a __________ charged solid support.
The partition coefficient is defined as the ratio of solute concentration in the mobile phase to that in the stationary phase.
The partition coefficient is defined as the ratio of solute concentration in the mobile phase to that in the stationary phase.
Which type of resin is used to attract anions in ion-exchange chromatography?
Which type of resin is used to attract anions in ion-exchange chromatography?
What happens to polar molecules during the partition chromatography process?
What happens to polar molecules during the partition chromatography process?
Match the following chromatography methods with their descriptions.
Match the following chromatography methods with their descriptions.
The stationary phase in partition chromatography is composed of a __________ liquid that is partially miscible with the flowing liquid.
The stationary phase in partition chromatography is composed of a __________ liquid that is partially miscible with the flowing liquid.
What is one of the primary uses of ion-exchange chromatography?
What is one of the primary uses of ion-exchange chromatography?
Match each term with its correct description:
Match each term with its correct description:
The stationary phase in ion-exchange chromatography consists of __________ polymers.
The stationary phase in ion-exchange chromatography consists of __________ polymers.
Which factor influences the rate at which a solute moves between the two phases in partition chromatography?
Which factor influences the rate at which a solute moves between the two phases in partition chromatography?
A separatory funnel is often used for the simple implementation of partition or extraction processes.
A separatory funnel is often used for the simple implementation of partition or extraction processes.
In partition chromatography, the two immiscible liquids are usually an organic solvent and a __________ solvent.
In partition chromatography, the two immiscible liquids are usually an organic solvent and a __________ solvent.
Study Notes
Adsorption Chromatography
- Oldest form of chromatography
- Utilizes competition between the sample and the mobile phase for spots on the stationary phase
- Most soluble = moves fastest
- Preferred as a preparative method for separating large quantities of mixtures with varying polarities and structures
- Requires the adsorbent to be insoluble in the solvent used
- Adsorbent strength is measured by the rate a zone travels in an elution experiment
- Strong adsorbents include alumina, fuller's earth, charcoal, and silica gel
- Intermediate adsorbents include magnesia, calcium carbonate, and calcium phosphate
- Weak adsorbents include sucrose, starch, talc, and inulin
- The ability to separate mixtures depends on the polarity of the functional groups
- Acidic polar stationary phases (ex. Silica Gel) are paired with a single solvent
- Basic polar stationary phases (ex. Alumina) utilize a mixture of two or more solvents
- Non-polar stationary phases (ex. Charcoal) also use a mixture of solvents
Partition Chromatography
- Separation is based on relative solubility in organic and aqueous solvents
- The stationary phase is a liquid partially miscible with the mobile phase
- Stationary phase may be coated on an inert chromatographic support
- Results in the partitioning of solute molecules in two phases
- The partition coefficient determines the rate a solute moves between phases
- Compounds most soluble in the mobile phase move faster and are easily eluted
- Compounds with high partition coefficients are retained in the stationary phase
Steric Exclusion Chromatography
- Separates solutes based on size and shape
- Early methods include: gel filtration, gel permeation chromatography
- Gel filtration: uses hydrophilic beads of cross-linked dextran, polyacrylamide gel, or agarose
- Gel permeation chromatography: uses hydrophobic gel beads of polystyrene
Ion-Exchange Chromatography
- Separates solutes based on charges
- Utilized to remove interfering substances from a solution
- Used for amino acid and hemoglobin analysis
- Used to separate mixtures of small organic and inorganic ions and charged molecules
- Concentrates dilute ion solutions
- Separates ions based on magnitude and change through ion exchange
- Solutes are eluted with a solution of low to medium salt concentration containing competing counter ions
- Change in pH and ionic concentration allows separation of organic and inorganic ions
- Separates charged molecules based on their attraction to a charged stationary phase
- Cation exchange resin
- Cations are free to react with hydrogen ions
- Sodium is used for cation exchange
- Positively charged molecules are attracted to a negatively charged solid support
- Anion exchange Resin
- Anions are free to react with hydroxyl ions
- Chloride is used for anion exchange
- Negatively charged molecules are attracted to a positively charged solid support
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Description
This quiz explores the fundamental principles of adsorption chromatography, the oldest form of chromatography. It covers the competition between samples and the mobile phase, the characteristics of various adsorbents, and methodologies for separating mixtures based on polarity. Test your knowledge on how different stationary phases work with solvents.
