Tag: methods of purification - organic compounds

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

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

  1. $CH _{4}-SP^{3}$
  2. $C _{2}H _{4}-sp^{2}$
  3. $C _{2}H _{2}-sp$

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

CH4− Alkane SP3

C2H4- Alkene SP2
C2H2- Alkyne SP

Hence all hybridization of carbon are correct

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

Assertion: 

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

Reason: 
The difference between their boiling point is very less

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $\text{A}$
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

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

  1. Phenol & naphthalene

  2. Benzol & pitch

  3. Anthracene & creosote

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

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