Chemistry · Science General

Separation Techniques

842 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 basic analytical techniques filtration and crystallisation other methods of separation separation techniques

A mixture of barium sulphate and $H _2O$ can be separated by the method of filtration.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A mixture of barium sulphate and $H _2O$ can be separated by the method of filtration. Barium sulphate is insoluble in water.  During filtration, barium sulphate remains on the filter paper and water passes as through filter paper as filtrate.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Sublimation is used to separate :

  1. two liquids having different boiling points

  2. two liquids having same melting point

  3. volatile and non volatile solids

  4. volatile solids having same melting point
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Which of the following mixtures cannot be separated by sublimation?

  1. Salt and ammonium chloride

  2. Salt and naphthalene

  3. Salt and camphor

  4. Camphor and naphthalene
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Sublimation is the transition of a substance directly from the solid to the gas phase without passing through the intermediate liquid phase. Ammonium chloride, camphor, anthracene, napthalene can sublime but common salt cannot sublime. Hence, option D is correct.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Which technique is used to separate salt from the filtrate after sublimation of ammonium chloride? 

  1. Evaportion

  2. Condensation

  3. Centrifugation

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

Evaporation technique is used to separate salt from the filtrate. Common salt does not decompose during evaporation. As the water evaporates, fewer and fewer water molecules are present to keep the salt particles apart. The salt therefore recrystallizes and can be collected.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Why is it difficult to separate salt and ammonium chloride mixture and sublimation is the only method to do so?

  1. Both are white in colour

  2. Both are soluble in water

  3. Both A and B

  4. None of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Both salt and ammonium chloride are white in colour and soluble in water. They can't be separated by any other method except sublimation.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

In the procedure of sublimation, the inverted funnel in plugged with cotton, because __________.

  1. cotton stops external air to enter in funnel

  2. cotton helps in sublimation

  3. ammonium chloride is a evaporating substance, which directly evaporate on heating without converting into liquid phase.

  4. all of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

During separation procedure of ammonium chloride from salt by evaporation an inverted funnel is used which is plugged with cotton boll, so that ammonium chloride do not evaporate.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

In the process of separation of ammonium chloride from the salt, ammonium chloride molecule ________. 

  1. evaporate

  2. sublime

  3. crystallize

  4. all of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The ammonium chloride molecule in separation from salt sublime and get separated. This is a sublimation process which is used to separate two solids. Here salt being non-volatile does not undergo sublimation. 

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Which of the following is not a way to separate the components of a mixture?

  1. Evaporation

  2. Electrolysis

  3. Chromatography

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

In Electrolysis, the current is passed through the solution and compound gets ionised, with electrolysis we can separate hydrogen and oxygen from pure water, but we can't use this method to separate components of a mixture.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Fractional crystallization is a method of refining substance based on difference on their:

  1. boiling point

  2. solubility

  3. hardness

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

In fractional crystallization, the component with low solubility will crysatllize first and one with high solubility will crystallize latter, so substances can be refined based on the difference on their solubility.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Solid-solid mixtures are separated by:

  1. Filtration

  2. Distillation

  3. Sublimation

  4. None of these
Reveal answer Fill a bubble to check yourself
A,C Correct answer
Explanation

Physical separation techniques depend on the physical properties of the substance. These physical properties include physical state, solubility, boiling point, melting point, density, specific gravity, electrical and magnetic properties.

  1. Washing: Insoluble solids like noble metals and compounds like silica can be washed with water until all the other impurities leave them. Washing can also be done with organic solvents when there is a mixture with soluble impurities and insoluble compound.
  2. Decanting: When the densities of two liquids that are immiscible in one another are to be separated this method can be used. Separating funnel helps to separately collect the tow liquids. In case of solids the lighter solids can be separated by decanting it in water medium when both of the solids are not soluble. By blowing air also the separation can be done with very light and heavy solid mixtures.
  3. Distillation: Mixtures of liquids can be separated when their boiling points are different by this technique. The mixture is slowly heated in a distillation flask. The component having the low boiling point vaporizes first. The vapors are collected by condensing them in Leibig's condenser. Mixtures containing more than two liquids can also be separated by this technique but the difference in boiling points must be at least 20C between each of them. Distillation can also be used to separate dissolved salts from their aqueous solutions. Sea water is distilled by the Sun rays to form clouds which rain fresh water without salts. Mixture of gases are separated by reducing their temperature and converting all the gases in to liquid state. By gradational increasing of temperatures each liquified gas gets converted into gaseous state and can be separated.
  4. Fractional distillation: When the difference in the boiling points are nearby to each other and not much, a detailed distillation is carried out which is called fractional distillation. It is done in a column called fractionating column. Fractionating column allows the condensation of different solvents at different temperatures and sending back the mixture fraction in to the flask. Petroleum distillation is done in the fractionating column in to various components over a wide range of temperatures. Melting point differences can also be utilized in the same way as boiling point in separation of mixtures. Icebergs are formed which are solidified fresh water is based on the depression of freezing point phenomenon.
  5. Solubility: Different compounds have different amounts of solubility at a certain temperature. When no more solid is soluble in solvent at a particular temperature it is called its saturation point at that temperature. In a mixture if one component is more soluble and the other less at a given temperature, they can be separated by this technique.
  6. Electrical and Magnetic separation: Electrolytes and non electrolytes, magnetic and non magnetic substances can be separated by this technique of separation using either electrical field or magnetic field.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Name a technique used to separate : Sodium chloride and sugar.

  1. filtration and evaporation

  2. filtration and distillation

  3. filtration and sublimation

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

sugar is organic,(contains carbon) and is soluable in organic solvents like alcohol. Salt is insoluable in alcohol. 
Add alcohol to the mixture, filter out the salt, then evaporate the alcohol and the sugar will be left.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

Apart from salt and ammonium chloride, which other mixture can be separated by sublimation?

  1. Salt and napthalene

  2. Salt and sugar

  3. Sugar and ammonium chloride

  4. Sugar and anthracene
Reveal answer Fill a bubble to check yourself
A,C,D Correct answer
Explanation

Sublimation can be used to separate all those substances which can sublimise easily like naphthalene, ammonium chloride and anthracene.

Multiple choice chemistry basic analytical techniques filtration and crystallisation other methods of separation separation techniques

After sublimation of ammonium chloride, how can salt be separated from the filtrate?

  1. Condensation

  2. Chromtography

  3. Evaporation

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

Evaporation technique is used to separate salt from the filtrate. Common salt does not decompose during evaporation. As the water evaporates, fewer and fewer water molecules are present to keep the salt particles apart. The salt, therefore, recrystallizes and can be collected.