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Chromatography and Purification

Description: This quiz is designed to assess your understanding of the principles and techniques of chromatography and purification methods used in the separation and analysis of chemical compounds.
Number of Questions: 15
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Tags: chromatography purification separation techniques analytical chemistry
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What is the primary principle behind the separation of compounds in chromatography?

  1. Differential solubility

  2. Differential volatility

  3. Differential adsorption

  4. Differential ionization


Correct Option: C
Explanation:

In chromatography, compounds are separated based on their differential adsorption to a stationary phase, which can be a solid or a liquid.

Which of the following is not a type of chromatography:

  1. Gas chromatography

  2. Liquid chromatography

  3. Thin-layer chromatography

  4. Electrophoresis


Correct Option: D
Explanation:

Electrophoresis is not a type of chromatography as it separates molecules based on their charge and size, rather than their differential adsorption.

In gas chromatography, the mobile phase is:

  1. A liquid

  2. A solid

  3. A gas

  4. A supercritical fluid


Correct Option: C
Explanation:

In gas chromatography, the mobile phase is a carrier gas, typically helium or nitrogen, which carries the sample through the column.

The stationary phase in liquid chromatography is typically:

  1. A solid

  2. A liquid

  3. A gas

  4. A supercritical fluid


Correct Option: A
Explanation:

In liquid chromatography, the stationary phase is a solid matrix, such as silica gel or alumina, which adsorbs the sample components.

The separation of compounds in thin-layer chromatography is based on:

  1. Differential solubility

  2. Differential volatility

  3. Differential adsorption

  4. Differential ionization


Correct Option: C
Explanation:

In thin-layer chromatography, compounds are separated based on their differential adsorption to a stationary phase, which is a thin layer of adsorbent material coated on a glass or plastic plate.

Which of the following is not a type of detector used in chromatography:

  1. Flame ionization detector

  2. Mass spectrometer

  3. Ultraviolet-visible detector

  4. Refractive index detector


Correct Option: B
Explanation:

Mass spectrometry is not typically used as a detector in chromatography, as it is a separate analytical technique used to identify and characterize compounds.

The purpose of a guard column in chromatography is to:

  1. Protect the analytical column from contaminants

  2. Increase the separation efficiency of the column

  3. Reduce the backpressure in the column

  4. Improve the sensitivity of the detector


Correct Option: A
Explanation:

A guard column is placed before the analytical column to protect it from contaminants that may be present in the sample or mobile phase.

Which of the following is not a factor that affects the resolution of a chromatographic separation:

  1. Column length

  2. Particle size of the stationary phase

  3. Flow rate of the mobile phase

  4. Temperature of the column


Correct Option: D
Explanation:

Temperature typically does not have a significant effect on the resolution of a chromatographic separation.

The elution order of compounds in chromatography is generally determined by their:

  1. Molecular weight

  2. Polarity

  3. Boiling point

  4. Solubility


Correct Option: B
Explanation:

In general, more polar compounds elute first in chromatography, as they have a stronger interaction with the stationary phase.

Which of the following is not a type of purification technique:

  1. Crystallization

  2. Distillation

  3. Chromatography

  4. Extraction


Correct Option: C
Explanation:

Chromatography is a separation technique, not a purification technique.

The process of removing impurities from a substance by dissolving it in a solvent and then filtering it is known as:

  1. Crystallization

  2. Distillation

  3. Extraction

  4. Filtration


Correct Option: D
Explanation:

Filtration is a purification technique that involves removing impurities from a substance by dissolving it in a solvent and then filtering it.

Which of the following is not a type of extraction technique:

  1. Solid-liquid extraction

  2. Liquid-liquid extraction

  3. Gas-liquid extraction

  4. Supercritical fluid extraction


Correct Option: D
Explanation:

Supercritical fluid extraction is not a type of extraction technique, as it involves the use of a supercritical fluid as the extracting agent.

The process of separating a mixture of liquids based on their different boiling points is known as:

  1. Crystallization

  2. Distillation

  3. Extraction

  4. Chromatography


Correct Option: B
Explanation:

Distillation is a purification technique that involves separating a mixture of liquids based on their different boiling points.

Which of the following is not a type of crystallization technique:

  1. Cooling crystallization

  2. Evaporative crystallization

  3. Precipitation crystallization

  4. Chromatographic crystallization


Correct Option: D
Explanation:

Chromatographic crystallization is not a type of crystallization technique, as it involves the use of chromatography to separate and purify compounds.

The process of purifying a substance by converting it into a salt and then recrystallizing it is known as:

  1. Crystallization

  2. Distillation

  3. Extraction

  4. Salt formation


Correct Option: D
Explanation:

Salt formation is a purification technique that involves converting a substance into a salt and then recrystallizing it.

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