Tag: methods of purification of organic compounds

Questions Related to methods of purification of organic compounds

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. $3$

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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

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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

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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

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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

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Correct Option: D
Explanation:

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