Chemistry · Science General

Separation Techniques

813 Questions

Separation techniques involve physical methods to isolate mixtures, including distillation, filtration, and crystallization. Competitive exams frequently test these foundational concepts. Review the exact processes to enhance problem solving speed.

Distillation and evaporationCrystallization processFiltration methodsSeparating dissolved solidsChromatography and mass techniques

Separation Techniques Questions

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

A homogeneous liquid-liquid solution is separated by:

  1. distillation

  2. decantation

  3. sublimation

  4. filtration
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Distillation is a method of separating mixtures based on differences in their volatiles in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction. Water is distilled to remove impurities, such as salt from seawater. 

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

Explain how individual gases can be separated from a gaseous mixture of $O _2$, $H _2$ and $CO _2$.

  1. Passing through $KOH$ solution, then diffusion

  2. Partial evaporation, then diffusion

  3. Preferential liquefaction, then partial evaporation

  4. All of the above
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Individual gases can be separated from a gaseous mixture of $O _2$, $H _2$ and $CO _2$ passing through $KOH$ solution, then diffusion. $KOH$ will absorb $CO _2$ gas. $O _2$ and $H _2$ have different rates of diffusion as they have different molecular weights.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

How will you separate dioxide, from the mixture of carbon monoxide and carbon dioxide?

  1. By passing through water under high pressure

  2. By passing through concentrated NaOH solution

  3. by passing through ammonical cuprous

  4. All the above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The mixture of carbon monoxide and carbon dioxide can be separated by passing the mixture through water under high pressure or through concentrated NaOH solution.Also mixture can be separated by passing it through ammonical cuprous.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

To separate a mixture of two or more gases ___________ method is used.

  1. sedimentation

  2. liquification

  3. distillation

  4. decantation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To separate a mixture of two or more miscible liquids for which the difference in boiling points is less than 25 K, fractional distillation process is used.

For example, for the separation of different gases from air.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

_______ is a method of separation that works on adsorption :

  1. Crystallization

  2. Chromatography

  3. Gravity separation

  4. Filteration
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chromatography is a method of separation that works on adsorption. Different components of the mixture have different affinities for the stationary phase and the mobile phase. In other words, the extent of adsorption on the stationary phase, is different for different components of the mixture.

Due to this,  different components of the mixture travel at different speeds. This results in the separation.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

Fractional distillation is a separation process for :

  1. Liquid-liquid

  2. Liquid-solid

  3. Solid-solid

  4. Both b and c
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Fractional distillation is a separation process for liquid-liquid mixture into its component parts, or fractions.
The separation depends on the difference in the  boiling point (usually 25 $^o$C at 1 atm) of individual components. The mixture is heated to a temperature at which one or more fractions of the compound will vaporize.   
For boiling point difference greater than 25 $^o$C, a simple distillation is used.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

Membranes used in solubility based gas separation are :

  1. Inorganic

  2. Polymeric

  3. Hybrid membrane

  4. All of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Membranes used in solubility based gas separation are inorganic, polymeric and hybrid membranes.
Microporous inorganic membranes are usually amorphous in nature and formed from metals, ceramics, or pyrolyzed carbon. The use of polymer membrane has generated an increasing interest in gas separation. Also different types of membrane has been used to enhance gas separation.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

$\displaystyle { CO } _{ 2 }$ and $\displaystyle CO$ can be separated by :

  1. Chromatography

  2. Solvent extraction

  3. Separation funnel

  4. Magnetic separation
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 A gaseous mixture containing CO$ _2$ and CO can be separated by solvent extraction.
The mixture is passed through water.  CO$ _2$ dissolves in water whereas CO does not.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

______ is useful when one gas is easily liquefiable.

  1. Solvent extraction

  2. Crystallisation

  3. Liquefaction

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Liquefaction is useful when one gas is easily liquefiable.
Liquefaction of gases is the process by which a gas is converted to a liquid by applying high pressure and low temperature. For example, oxygen normally occurs as a gas. However, by applying high pressure and by reducing the temperature, oxygen can be converted to a liquid.
Note:
In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under pressure
Liquefaction of gases is the process by which a gas is converted to a liquid. In a mixture of NH$ _3$ and H$ _2$, NH$ _3$ gets liquefied under high pressure and H$ _2$ is left behind.
NH$ _3$ has higher value of the van der Waal's constant 'a' than
Hence, NH$ _3$ is more easily liquefiable than H$ _2$.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

Which of the following cannot be used for liquid-liquid separation?

  1. Magnet

  2. Sublimation

  3. Crystallization

  4. All of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Magnetic separation and sublimation can be used to separate solid from solid. Crystallization is used to recover solid from liquid. Hence, none of the above methods is used for separation of liquid from liquid.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

A technique in which two liquids are separated by heating process is known as :

  1. distillation

  2. filtration

  3. evaporation

  4. sublimation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Distillation is a process of separating the component or substances from a liquid mixture by selective evaporation and condensation. Distillation may result in essentially complete separation (nearly pure components), or it may be a partial separation that increases the concentration of selected components of the mixture.

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

A cheque was suspected to be forged. Which technique could be used to compare the various pigments in the different inks?

  1. Chromatography

  2. Evaporation

  3. Crystallisation

  4. Sublimation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A cheque was suspected to be forged. Chromatography could be used to compare the various pigments in the different inks.  Here, different inks will have different affinity for  stationary phase  and solvent (mobile phase).

Multiple choice separation of components of mixtures methods of separation elements, compounds and mixtures chemistry

Fractional distillation is used to obtain the components of which of the following?
I air
II seawater
III muddy water
IV crude oil 

  1. I, II

  2. II, III

  3. I, IV

  4. I, III
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Fraction distillation is based upon the separation of components having very less boiling point difference, therefore components of crude oil and air can be separated using fractional distillation. In the air and in crude oil, the difference in boiling point of different components is very less.