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 chemistry separation of substances classification of mixtures mixtures: examples and properties types of solutions

Substances are separated, because the :

  1. harmful substance can be removed

  2. non-useful substance can be removed

  3. useful substance, which we require separately

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

Separation of a mixture is done in order to :


(i) remove impurities or harmful substances.


(ii) to get pure substance.

(iii) to separate the components of the mixture and get the useful substance which is required, separately.


Hence the option D is correct.

Multiple choice evs - i life is precious road safety and pollution pollution of natural resources air pollution and its effects

______ is a device for separation of pollutants from air.

  1. Autoclave

  2. Distillator

  3. Scrubber

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

There are several contaminants found in air. It is very important to purify this polluted air .A fine spray of water in a device known as scrubber can effectively separate many gases such as ammonia and sulphur dioxide.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Steam distillation is used for the extraction of_____________.

  1. essential oil

  2. higher alkynes

  3. mineral oils

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

Steam distillation is used to separate essentials oils so that the temperature goes nowhere near their boiling points,
which minimises the risk of decomposition.
Steam distillation is used and not simple distillation for separating essential oils.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

How will you separate mixture of two gases? 

  1. Fractional distillation technique

  2. Grahams law of diffusion technique

  3. Osmosis

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

A mixture of two gases can be separated by fractional distillation technique. Fractional distillation is a process by which components in a chemical mixture are separated into different parts called fractions according to their different boiling points.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

___________ is a separation process for temperature sensitive materials like natural aromatic compounds.

  1. Vacuum distillation

  2. Steam distillation

  3. Fractional distillation

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
True (2)
Steam distillation is a special type of distillation (a separation process) for temperature sensitive materials like natural aromatic compounds. It once was a popular laboratory method for purification of organic compounds but has become obsolete by vacuum distillation.
In steam distillation, steam is used to lower the distillation temperatures of high boiling organic compounds that are immiscible with water. In the process, steam is charged to the matrix to volatilise the hydrophobic liquid and carry it across to a chilled condenser for subsequent liquefaction and separation from water. Variations in temperature, pressure and distillation time are used to control the process. 
Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Simple distillation can be used to separate:

  1. a mixture of benzene (b.pt. $80^{o}$C) and toluene (b.pt. $110^{o}$C)
  2. a mixture of ether (b.pt. $35^{o}$C) and toluene (b.pt. $110^{o}$C)
  3. a mixture of ethanol (b.pt. $78^{o}$C) and water (b.pt. $100^{o}$C)

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

Simple distillation is used to separate volatile liquids from non-volatile impurities having sufficient difference in their in their boiling points.
A mixture of ether (B.P $35^{0}$) and toluene (B.P $110^{0}$) since they have large boiling point difference.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Which is/are the correct method for separating a mixture of benzoic acid, p-methylaniline & phenol.

  1. $\xrightarrow {aq.NaHCO _3}$ $ \xrightarrow {aq.NaOH}$
  2. $\xrightarrow {aq.HCl}$ $ \xrightarrow {aq.NaHCO _3}$
  3. $\xrightarrow {aq.NaOH}$ $\xrightarrow {aq.NaHCO _3}$
  4. $\xrightarrow {aq.NaOH}$ $ \xrightarrow {aq.HCl}$
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques
By reducing the pressure in the container, the boiling point of liquids in the mixture can be reduced and the mixture can be distilled at a lower temperature. This technique is called:

  1. vacuum distillation

  2. steam distillation

  3. fractional distillation

  4. none of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapour pressure causing evaporation of the most volatile liquids.

Steam distillation is a special type of distillation for temperature sensitive materials like natural aromatic compounds. Many organic compounds tend to decompose at high sustained temperatures. Separation by distillation at the normal (1 atmosphere) boiling points is not an option, so water or steam is introduced into the distillation apparatus. 

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Styrene can be purified by:

  1. Simple distillation

  2. Fractional distillation

  3. Vacuum distillation

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

Styrene is heat-sensitive and tends to polymerize at its normal boiling point. Therefore, it must be purified by vacuum distillation to lower its boiling point.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

p-nitrophenol and o-nitrophenol are separated by?

  1. Crystallisation

  2. Fractional distillation

  3. Distillation

  4. Steam distillation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

o-Nitrophenol exhibits intramolecular hydrogen bonding, making it more volatile than p-nitrophenol, which exhibits intermolecular hydrogen bonding. Steam distillation exploits this difference in volatility.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

Turpentine oil can be purified by:

  1. steam distillation

  2. vaccum distillation

  3. fractional distillation

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

Steam distillation of a liquid in a current of steam used especially to purify liquids that are not very volatile and are immiscible with water. The boiling point of turpentine oil is between 90 and 115 °C or 195 and 240 °F and is immiscible with water. Thus, it is purified by steam distillation.

Multiple choice bio-chemistry biochemical techniques methods of purification of organic compounds methods of purification - organic compounds chromatography

A mixture of camphor and benzoic acid can be easily separated by?

  1. Sublimation

  2. Fractional distillation

  3. Chemical method

  4. Extraction with solvents
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Aqueous solution of $NaHCO _3$ can be used to separate benzoic acid from its mixture with camphor. Benzoic acid forms water soluble sodium benzoate with $NaHCO _3$. So, A mixture of camphor and benzoic acid can be easily separated by Chemical method.

Option C is correct.

Multiple choice chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

A substance which decomposes at or below its boiling point cannot be purified by?

  1. Steam distillation

  2. Simple distillation

  3. Fractional distillation

  4. Distillation under reduced pressure
Reveal answer Fill a bubble to check yourself
A,B,C Correct answer
Explanation

Steam distillation is used for natural aromatic compounds which are immiscible in water.
Simple and fractional distillation uses the property of difference in the boiling point. These techniques can not be used for the substance which decomposes at or below its boiling point.
Distillation under reduced pressure is basically Vaccum distillation. This method is used to boil such substances without their decomposition

Option A, B and C are the answer.