• Methods of purification - organic compounds - class-XI
Back
0

Methods of purification - organic compounds - class-XI

Description: methods of purification - organic compounds
Number of Questions: 49
Created by:
Tags: chemistry biochemical techniques bio-chemistry organic chemistry - some basic principles and techniques organic chemistry : some basic principles and techniques
Start the Quiz
Attempted 0/49 Correct 0 Score 0
‹
›

Which one of the following reagent is useful for separating aniline from nitrobenzene?

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

  1. $ aq. NaHCO _3 $

  2. $ aq. NaHSO _3 $

  3. $ aq. HCl $

  4. $dil. H _2SO _4 $

Show answer
Correct Option: C
Explanation:

The reagent selected should be such that only one of components to be separated, reacts with it.


Aniline $+$ aq, HCl $\rightarrow$ salt, which is soluble in water
Nitrobenzene $+$ aq. HCl$\rightarrow$ no reaction.

Therefore, aq. HCL is used to separate aniline and nitrobenzene.

 A mixture of two immiscible liquids chlorobenzene and water boils at $90^{0}C$ and an external pressure of 740.2 torr. If vapour pressure of pure water at $90^{0}C$ is 530 torr then the mole % of chlorobenzene in the distillate will be:

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

  1. 80%

  2. 40%

  3. 28%

  4. 60%

Show answer
Correct Option: C

Mixed melting point is determined to check.

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

  1. The purity of organic compound

  2. Whether the two compounds are same

  3. Whether the two compounds are different

  4. Whether the two compounds can be separated by fractional crystallisation method

Show answer
Correct Option: A,B,C

Match the following:

(A) Sublimation (i) Ether $+$ toluene
(B) Distillation (ii) o-Nitrophenol $+$ p-nitrophenol
(C) Vacuum distillation (iii) Benzoic acid $+$ benzaldehyde
(D) Steam distillation (iv) Glycerol from spent lye
methods of purification of organic compounds methods of purification - organic compounds organic chemistry - some basic principles and techniques organic chemistry : some basic principles and techniques chemistry biochemical techniques

  1. (A)-(iv), (B)-(iii), (C)-(ii), (D)-(i)

  2. (A)-(i), (B)-(ii), (C)-(iii), (D)-(iv)

  3. (A)-(iii), (B)-(i), (C)-(iv), (D)-(ii)

  4. (A)-(ii), (B)-(iv), (C)-(i), (D)-(iii)

Show answer
Correct Option: C

Compare List I and List II and choose the correct matching codes from the choices given.


List I List II
(A) Glycerol (i) Sublimation
(B) o-nitrophenol (ii) Beilstein's test
(C) Anthracene (iii) Victor-Meyer's method
(D) Halogens (iv) Steam distillation
(E) Molecular weight (v) Vacuum distillation
(vi) Eudiometry


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

  1. (A-v), (B-iv), (C-i), (D-ii), (E-iii)

  2. (A-iv), (B-v), (C-i), (D-vi), (E-ii)

  3. (A-vi), (B-iv), (C-i), (D-iii), (E-ii)

  4. (A-v), (B-iv), (C-vi), (D-ii), (E-iii)

  5. (A-iv), (B-vi), (C-ii), (D-iii), (E-v)

Show answer
Correct Option: A
Explanation:
  • Sublimation-Conversion of solid directly into gaseous phase. The liquid state does not exist. e.g., naphthalene, anthracene. 
  • Beilstein test-Simple chemical test for halogens. 
  • Victor-Meyers method-Standard laboratory method for determining the molecular weight of a volatile liquid. 
  • Steam distillation- Vaporization of the volatile constituents of a liquid. It is special type of distillation for temperature-sensitive materials like aromatic natural compounds, eg,-ortho nitrophenol, cinnamaldehyde. 
  • Vacuum distillation-Distillation at reduced pressure. It is generally used in case of high boiling liquids which decompose below their normal boiling points, cant be purified by distillation at atmospheric pressure.
  • Eudiometry-It is the process of determining the constituents of a gaseous mixture by eudiometer. It is used for ascertaining the purity of air or amount of $O _2$ in it.

Mixture of benzene and aniline can be separated by?

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

  1. Distillation

  2. Steam distillation

  3. dil. HCl

  4. di. NaOH

Show answer
Correct Option: A,C

Which method cannot be used for purification
of liquids?

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

  1. Chromatographic

  2. Steam distillation

  3. Sublimation

  4. Distillation

Show answer
Correct Option: C
Explanation:

Sublimation is the process in which solid changes directly to vapour state without passing through the liquid state.So sublimation cannot be used for purification of liquids.

Choose the correct option for the two statements given below :
Statement I: Sharp melting point can be used to test the purity of the compound.
Statement II: Impurities cause a decrease in the melting point of the compound.

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

  1. Both statements I and II are correct.

  2. Both statements I and II are incorrect.

  3. Statement I is correct and statement II is incorrect.

  4. Statement I is incorrect and statement II is correct.

Show answer
Correct Option: A
Explanation:

The purity of an organic compound can be tested by its sharp melting point. The impurities present in the compound can cause a decrease in melting point.


The presence of even a small amount of impurity will lower a compound's melting point by a few degrees and broaden the melting point temperature range.

Option A is correct.

Assertion (A): Components of rectified spirit
cannot be separated by distillation
Reason (R): Rectified spirit is an Azeotropic
mixture

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

  1. Both A and R are true and R is correct explanation of A

  2. Both A and R are true and R is not correct explanation of A

  3. A is true but R is false

  4. A is false but R is true

Show answer
Correct Option: A
Explanation:

An azeotropic is a mixture of 2 or more liquids in such a way that its components cannot be altered by simple distillation, This happens because when an azeotrope is barred, the vapour has the same proportions of constituents as the unboiled mixture.
Azeotropes are also called constant boiling mixture,
Rectified spirit is an azeotropic mixture of ethanol and water. 

d- tartaric acid and l - tartaric acid can be separated by:

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

  1. salt formation

  2. fractional distillation

  3. fractional crystallisation

  4. chromatography

Show answer
Correct Option: A
Explanation:

d- tartaric acid and l - tartaric acid can be
separated by Salt formation.
Two enantiomers of sodium ammonium salt of tartaric acid give rise to two distinctly different types of chiral crystals that can be easily separated.

The best solvent for the crystallization of organic solid is in which:

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

  1. organic compound is highly soluble

  2. compound is soluble on warming

  3. compound is soluble at $90^{0}$

  4. compound is insoluble

Show answer
Correct Option: B
Explanation:

Generally speaking you need to take polar solvents for polar compound and nonpolar solvents for nonpolar compounds. Many times a mixture of solvents works better. Once you have this basic idea, crystallization is a skill developed over a period of time by trial and error process. Even after long experience you may not hit the right solvent in the first try.

In fractional distillation of petroleum, the vapours with highest boiling point ____________.

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

  1. condense in upper most portion'

  2. condense in lower most portion

  3. condense in middle portion

  4. none of these

Show answer
Correct Option: B
Explanation:

The fractional column is hot at the bottom and cool at the top. Substances with high boiling points condense at the bottom and substances with lower boiling points condense on the way to the top.

Which of the following method is used for the purification of solids?

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

  1. Distillation under reduced pressure

  2. Distillation

  3. Steam distillation

  4. Sublimation

Show answer
Correct Option: D
Explanation:

Sublimation is the process in which solid gets converted into vapours directly without passing through the liquid state.

Which of following is incorrectly matched?

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

  1. Distillation - Liquids stable at their boiling point

  2. Distillation under reduced pressure - Liquids that decompose at their boiling point

  3. Steam distillation - Liquids that are immiscible with water

  4. All are true

Show answer
Correct Option: D

There is a mixture of three solid compounds A, B and C. Out of these compounds A and Care soluble in water and compound C is sublimable also. In what sequence the following techniques can be used for their effective separation? 
I. Filtration
II. Sublimation
IIl. Crystallisation from water extract
IV. Dissolution in water

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

  1. (II), (I), (IV), (III)

  2. (IV), (I), (II), (III)

  3. (I), (II), (III), (IV)

  4. (II), (IV), (I), (III)

Show answer
Correct Option: D
Explanation:

Sublimation will separate C from A and B. On adding water, A will dissolve but B will not. B can be separated by filtration. A will be present in the filtrate and can be obtained by crystallisation from water extract.

What cant be removed after distillation of water?

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

  1. Suspensions

  2. Precipitates

  3. Volatile liquids like alcohol

  4. Dissolved salts

Show answer
Correct Option: C
Explanation:

Distillation is the process of purifying water by removing contaminants.

A volatile liquid has a comparatively smaller boiling point than the water thus it becomes difficult to separate them. 

Silt in water remains suspended. It is removed by sedimentation and filtration. For increasing its sedimentation aluminium sulphates and calcium hydroxide (slaked lime) are added. As a result sticky aluminium hydroxide.

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

  1. Destroys slit particles

  2. Attracts the particles of slit

  3. Mixes with slit particles

  4. Makes slit particles increases in size and deposit at the bottom

Show answer
Correct Option: B
Explanation:

The silt in $H _2O$ remains suspended. To attract some more silt particles, $Al(OH) _3$ is used. It is used to absorb the silt particles and make the liquid more pure.

Which of the following is a physico-chemical method of separation and purification?

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

  1. Electrolysis

  2. Distillation in a flask or a big tower

  3. Filtration through a filtering medium

  4. Leaching

Show answer
Correct Option: A
Explanation:

Electrolysis is the only physico-chemical method. Rest all are physical processes.

Refining of petroleum does not involve.

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

  1. Simple distillation

  2. Steam distillation

  3. Fractional distillation

  4. Distillation under reduced pressure

Show answer
Correct Option: A,C,D
Explanation:

The steam distillation process works on the principle that when a mixture of two or more undissolved liquids are heated, while ensuring that the surfaces of both liquids are in contact with the atmosphere, the vapor pressure exerted by the system increases. This method is used for the refining of petroleum. 


So, simple distillation, fractional distillation, distillation under reduced pressure are not involved in the refining of petroleum.

Options A, C, and D are correct answers.

Select the correct code by matching list I and list II.


 List -I    List -II
A) Fractional Distillation a) A liquid having sufficiently different boiling points
 B) Fractional Crystallization b) Solids having different solubilities
 C) Vacuum Crystallization c) A liquid that decomposes at its boiling point
 D) Solvent extraction d) Liquids of almost same boiling points

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

  1. A - a, B - b, C - c, D - d

  2. A - a, B - c, C - b, D - d

  3. A - d, B - c, C - b, D - a

  4. A - b, B - d, C - c, D - a

Show answer
Correct Option: C

Fractional distillation is used to separate liquids which differ in their boiling point by :

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

  1. $5$

  2. 10 to 20

  3. $30-80$

  4. $3$

Show answer
Correct Option: B,C

Which of the following is correct for hydbridization of C-atom?

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

  1. $CH _{4}-SP^{3}$

  2. $C _{2}H _{4}-sp^{2}$

  3. $C _{2}H _{2}-sp$

  4. All of these

Show answer
Correct Option: D
Explanation:

CH4− Alkane SP3

C2H4- Alkene SP2
C2H2- Alkyne SP

Hence all hybridization of carbon are correct

Steam distillation is used for the extraction of_____________.

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

  1. essential oil

  2. higher alkynes

  3. mineral oils

  4. fatty acids

Show answer
Correct Option: A
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.

How will you separate mixture of two gases? 

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

  1. Fractional distillation technique

  2. Grahams law of diffusion technique

  3. Osmosis

  4. Chromatography

Show answer
Correct Option: A
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.

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

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

  1. Vacuum distillation

  2. Steam distillation

  3. Fractional distillation

  4. None of the above

Show answer
Correct Option: B
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. 

Simple distillation can be used to separate:

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

  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

Show answer
Correct Option: B
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.

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

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

  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}$

Show answer
Correct Option: A,B

Assertion: 

A mixture of acetone and methanol can be separated by fractional distillation 

Reason: 
The difference between their boiling point is very less

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

  1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

  2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

  3. Assertion is correct but Reason is incorrect

  4. Both Assertion and Reason are incorrect

Show answer
Correct Option: A
Explanation:
A mixture of acetone and methanol both are polar therefore they are miscible and can interact with each other by H-bonding. 
The boiling point of Methanol is 64.7 $^o$C and boiling point of Acetone is 56 $^o$C.
So, it is very easy to separate them by fractional distillation.

Thus, Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
Hence, the correct option is $\text{A}$
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:
chemistry organic chemistry : some basic principles and techniques methods of purification of organic compounds methods of purification - organic compounds biochemical techniques

  1. vacuum distillation

  2. steam distillation

  3. fractional distillation

  4. none of these

Show answer
Correct Option: A
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. 

Which of the following is not a product of tar distillation?

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

  1. Phenol & naphthalene

  2. Benzol & pitch

  3. Anthracene & creosote

  4. None of these

Show answer
Correct Option: D
Explanation:

The distillation of tar do not give Phenol & naphthalene, or Benzol & pitch or Anthracene & creosote.

Styrene can be purified by:

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

  1. Simple distillation

  2. Fractional distillation

  3. Vacuum distillation

  4. Steam distillation

Show answer
Correct Option: C

The standard reduction potentials of $Pt|Cr {2}O _{7}^{2-}, Cr^{+3}; Pt|MnO _{4}^{-}, Mn^{+2}; Pt|Ce^{+4}, Ce^{+3}$ in the presence of acid are 1.33 V, 1.51 V and 1.61 V, respectively, at $25^{\circ}C$. The decreasing order of oxidizing power is _________________.

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

  1. $Cr _{2}O _{7}^{2-} > MnO _{4}^{-} > Ce^{+4}$

  2. $MnO _{4}^{-}> Cr _{2}O _{7}^{2-} > Ce^{+4}$

  3. $Ce^{+4} > MnO _{4}^{-}> Cr _{2}O _{7}^{2-}$

  4. $MnO _{4}^{-} > Ce^{+4} > Cr _{2}O _{7}^{2-}$

Show answer
Correct Option: C

Which of the following compounds can be purified by vacuum distillaiton?

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

  1. Glycerine

  2. Glycerol

  3. Propane-$1, 2, 3$-triol

  4. Ethanol

Show answer
Correct Option: A,B,C
Explanation:

Vacuum distillation is used when the boiling point of the compound or the solvent is too high in order to distill the compound or the solvent off without significant decomposition. It is based on the fact that under vacuum the boiling point of the materials is lower than at normal atmospheric pressure. Glycerine, glycerol and propone 1,2,3-triol are the three names of the same compound. It has a boiling point of 290$^oC$ while ethanol has BP 79$^oC$ .

Option A, B and C are correct.

p-nitrophenol and o-nitrophenol are separated by?

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

  1. Crystallisation

  2. Fractional distillation

  3. Distillation

  4. Steam distillation

Show answer
Correct Option: D

$ H _{2}O _{2}$ can be prepared by successive reactions:
$ 2NH _{4}HSO _{4}\rightarrow H _{2}+(NH _{4})^{2}S _{2}O _{8}$
$ (NH _{4}) _{2}S _{2}O _{8}+2H _{2}O \rightarrow  2NH _{4}HSO _{4}+ H _{2}O _{2}$
The first reaction is an electrolytic reaction and second is steam distillation. What amount of current would have to be used in first reaction to produce enough intermediate to yield 102 g pure $ H _{2}O _{2}$ per hour. Assume current efficiency 50 %.

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

  1. 643.33 A

  2. 321.67 A

  3. 160.83 A

  4. 1286.67 a

Show answer
Correct Option: B

Which of the following compounds can be purified by steam distillation?

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

  1. Salicylaldehyde

  2. Bromobenzene

  3. p-Hydroxy benzaldehyde

  4. Nitrobenzene

Show answer
Correct Option: A,B,D

Osazone formation is used to separate and identify.

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

  1. Alcohols

  2. Carboxylic acids

  3. Carbohydrates

  4. Starch

Show answer
Correct Option: C

Turpentine oil can be purified by:

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

  1. steam distillation

  2. vaccum distillation

  3. fractional distillation

  4. sublimation

Show answer
Correct Option: A
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.

Absolute alcohol can be prepared from rectified spirit by:

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

  1. Azeotropic distillation with benzene

  2. Fractional distillation

  3. Keeping over fresh CaO for few hours and then distilling

  4. Distillation under reduced pressure

Show answer
Correct Option: A,C

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

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

  1. Sublimation

  2. Fractional distillation

  3. Chemical method

  4. Extraction with solvents

Show answer
Correct Option: C
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.

Which of the following is not an exact differential?

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

  1. $dq$

  2. $dG$

  3. $d(\bar { V } )$

  4. $dS$

Show answer
Correct Option: A
Explanation:
Exact differential are those function if 
$\cfrac { \delta  }{ \delta T } (\cfrac { \delta f }{ \delta P } )=\cfrac { \delta  }{ \delta P } (\cfrac { \delta f }{ \delta T } )$ where f is the function of P and T. increase of q, it will not be equal , so it will be not exact function.

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

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

  1. Steam distillation

  2. Simple distillation

  3. Fractional distillation

  4. Distillation under reduced pressure

Show answer
Correct Option: A,B,C
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.

Component of urine can be separated by________.

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

  1. distillation

  2. filtration

  3. sedimentation

  4. decantation

Show answer
Correct Option: A
Explanation:

Due to the difference between the boiling point of components, distillation can be used for separation.

An organic liquid vaporizes at a temperature _________ its boiling point in steam distillation.

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

  1. above

  2. below

  3. equal to

  4. none of the above

Show answer
Correct Option: B
Explanation:

In steam distillation, the mixture boils when the sum of vapour pressures of water and the organic liquid becomes equal to the atmospheric pressure. Since the vapour pressure of water is appreciably higher than that of the organic liquid, it vaporizes at a temperature much lower than its normal boiling point. 

In this way, many organic compounds insoluble in water can be purified at a temperature well below the point at which decomposition occurs. 

In the destructive distillation of coal, at 443-503 K temperature, a middle oil or carbolic oil fraction is obtained. This fraction contains :

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

  1. Phenol

  2. Xylenes

  3. Naphthalene

  4. Benzene

Show answer
Correct Option: A,C
Explanation:

 (3) Distillation of coal tar : Arenes are isolated by fractional distillation of coal tar,

Table : 

Name of the fraction

Temperature range (K)

Main constituents

Light oil (or crude oil) fraction
Middle oil fraction (Carbolic oil)
Heavy oil fraction (Creosote oil)
Green oil (Anthracene oil)
Pitch (left as residue)

 So at 443-503 K temperature phenol and naphthalene is formed

Hence options A & C are correct.

Which of the following procedures will give you water free from all impurities?

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

  1. Adding chlorine tablets

  2. Distillation

  3. Boiling

  4. Filtration

Show answer
Correct Option: B
Explanation:

Distillation procedures will give us water free from all impurities. The distillation process removes almost all impurities from water. Distillers are commonly used for removing nitrate, bacteria, sodium, hardness (dissolved solids), most organic compounds, heavy metals and radionuclides from water. Distillers remove about 99.5% of the impurities from the original water.

The fragrance of the flower is due to the presence of some steam volatile organic compounds called essential oils. These are generally insoluble in water at room temperature but are miscible with water vapour in the vapour phase. A suitable method for the extraction of these oil from the flower is:

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

  1. distillation

  2. crystallisation

  3. distillation with reduced pressure

  4. steam distillation

Show answer
Correct Option: D
Explanation:

As the component is miscible with water vapour in vapour phase so steam distillation will be most suitable method for extraction.

Glycerin can be purified by:

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

  1. vacuum distillation

  2. simple distillation

  3. steam distillation

  4. fractional distillation

Show answer
Correct Option: A
Explanation:
The liquids which decompose at its boiling point can be purified by vacuum distillation. Glycerol decomposes at its boiling point (563K). It can be distilled by vacuum distillation without decomposition at 453K and under 12mm Hg pressure.

Distillation under reduced pressure is generally used to purify those liquid which:

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

  1. have very low boiling points

  2. are volatile

  3. have high boiling points and which decompose below their boiling points

  4. have a large difference in their boiling points.

Show answer
Correct Option: C
- Hide questions
ADVERTISEMENT

Find more quizzes from top tags

general knowledge
3615 Quizzes
119858 Questions
 technology
307 Quizzes
36705 Questions
 sports
963 Quizzes
19148 Questions
 history
1187 Quizzes
13475 Questions
 physics
598 Quizzes
13441 Questions
 biology
1160 Quizzes
12174 Questions
 science & technology
551 Quizzes
11015 Questions
 chemistry
490 Quizzes
9892 Questions
 maths
518 Quizzes
9324 Questions
 softskills
0 Quizzes
7131 Questions