Separation Techniques Quiz

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Questions and Answers

What is the main purpose of filtration?

Remove small solid particles from a mixture

Separate a solid from a liquid (correct)

Separate mixtures of liquids with different boiling points

Remove impurities from two solids

Why is vacuum filtration used instead of gravity filtration?

Liquid particles are too small and block the filter paper

Solid particles are too small and block the filter paper (correct)

Solid particles are too large to pass through the filter paper

Liquid particles are too large to pass through the filter paper

Distillation is effective because:

Components of the mixture are in the same physical state

Liquids in the mixture have different boiling points (correct)

Solids in the mixture have different melting points

Molecules in the mixture have different colors

Recrystallization is primarily used to:

Remove impurities from two solids Signup and view all the answers

Chromatography separates compounds based on differences in their:

Physical or chemical properties Signup and view all the answers

Gravity filtration differs from vacuum filtration in that gravity filtration relies on:

The force of gravity to pull the liquid through the filter paper Signup and view all the answers

What is the primary factor that leads to the separation of compounds in gas chromatography?

Affinity for the stationary phase Signup and view all the answers

Which compound is expected to be retained the longest in gas chromatography?

Compound 11 Signup and view all the answers

In gas chromatography, which detector burns all organic compounds and detects current?

Flame ionization detector Signup and view all the answers

What is the purpose of the liquid solvent or mixture of solvents in liquid chromatography?

Carry the sample through the chromatographic column Signup and view all the answers

Which component of a chromatograph contains the stationary phase and interacts with sample components?

Column Signup and view all the answers

What property is used for separation in liquid chromatography?

Polarity, size, or charge Signup and view all the answers

What is the purpose of wetting the filter paper with a small amount of solvent or solution before pouring the liquid mixture into the Büchner funnel?

To create a seal and improve filtration efficiency Signup and view all the answers

What role does turning on the vacuum source play in the filtration process described?

It creates a pressure difference that pushes liquid through the filter paper Signup and view all the answers

Why are different boiling points of components important for effective distillation?

To ensure complete separation of components Signup and view all the answers

How does ethanol's lower boiling point compared to water relate to its intermolecular forces?

Ethanol has weaker intermolecular forces than water Signup and view all the answers

What is the primary function of distillation in separating liquid mixtures?

To separate components based on their different boiling points Signup and view all the answers

How does strong hydrogen bonding contribute to higher boiling points in liquids?

By requiring more energy to transition to gas phase Signup and view all the answers

What is the main purpose of a UV-Visible detector in liquid chromatography?

Measures the absorbance of ultraviolet light to facilitate separation based on size Signup and view all the answers

In Size Exclusion Chromatography, why do smaller molecules take longer paths through the column?

They cannot enter the pores of the stationary phase Signup and view all the answers

What is the role of the mobile phase in liquid chromatography?

Facilitates movement of sample components through the column Signup and view all the answers

Why do larger molecules move more quickly through a Size Exclusion Chromatography column?

They cannot enter the pores of the stationary phase Signup and view all the answers

How are components separated in liquid chromatography?

By differential interaction with stationary and mobile phases Signup and view all the answers

Which type of liquid chromatography is specifically used to separate biomolecules based on their size?

Size Exclusion Chromatography Signup and view all the answers

Why do larger molecules elute first in chromatography?

They enter the non-porous path and move more quickly. Signup and view all the answers

What happens when a salt and sand mixture is combined with water?

Salt dissolves while sand remains insoluble. Signup and view all the answers

What is the main principle behind the separation of molecules in chromatography?

Differences in size Signup and view all the answers

Why are smaller molecules retained for a longer time in chromatography?

They enter the pores and have an extended path. Signup and view all the answers

What is the purpose of the detector in chromatography?

To record signals from eluting components Signup and view all the answers

Study Notes

Filtration and Its Variants

Main purpose of filtration is to separate solids from liquids.
Vacuum filtration uses suction to accelerate the filtration process, making it faster than gravity filtration.
Gravity filtration relies on the force of gravity to pull the liquid through the filter, which can be slower than vacuum filtration.

Distillation

Distillation is effective because it separates components based on differences in boiling points.
Different boiling points are crucial to ensure effective separation during distillation.
Ethanol has a lower boiling point than water due to weaker intermolecular forces, facilitating easier evaporation during distillation.
The primary function of distillation is to purify liquid mixtures by separating components.

Chromatography Techniques

Chromatography separates compounds based on differences in their affinities for the stationary and mobile phases.
In gas chromatography, the separation of compounds is primarily influenced by their vapor pressures.
Larger hydrocarbons typically have lower vapor pressures and are expected to be retained longer in gas chromatography.
A flame ionization detector in gas chromatography burns organic compounds to detect electrical current.

Liquid Chromatography

Purpose of the liquid solvent is to dissolve the sample and carry it through the chromatographic system.
The stationary phase exists within the chromatograph, interacting with sample components and facilitating separation based on various properties.
Property used for separation in liquid chromatography can include polarity, size, or charge.
Wetting the filter paper with solvent minimizes the loss of sample during filtration.
Turning on the vacuum source enhances filtration speed by creating a pressure differential.

Size Exclusion Chromatography (SEC)

In Size Exclusion Chromatography, smaller molecules take longer paths due to their ability to enter pores in the stationary phase, thereby increasing their travel time.
Larger molecules move more quickly through the column because they are excluded from the pores.
SEC specifically separates biomolecules based on size.

General Chromatography Principles

In chromatography, components are separated based on their differing interactions with the stationary and mobile phases.
Larger molecules elute first as they do not interact strongly with the stationary phase and can flow through the columns more freely.
Smaller molecules are retained longer due to their interactions with the stationary phase or being trapped in small pores.

Additional Details

When a salt and sand mixture is combined with water, the salt dissolves while the sand remains undissolved, illustrating the principle of solubility in chromatography.
The purpose of the detector in chromatography is to quantify and identify the separated components as they elute from the column.

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Description

Test your knowledge on separation techniques such as filtration, distillation, recrystallization, and chromatography. Learn how these methods use physical or chemical differences to separate compounds based on their properties.