Tag: petrochemicals and polymers

Questions Related to petrochemicals and polymers

Determine the degree of association (polymerization) for the reaction in aqueous solution
$6HCHO\rightleftharpoons C _6H _{12}O _6$
If observed (mean) molar mass of HCHO and $C _6H _{12}O _6$ is $150$.

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. $0.50$

  2. $0.833$

  3. $0.90$

  4. $0.96$

Show answer
Correct Option: D
Explanation:
Let us consider the problem.
$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, 6HCHO \,\,\,\,\,\leftrightarrow {C _6}{H _{12}}{O _6}$
At equation $c\left( {1 - \alpha } \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\dfrac{{C\alpha }}{6}$
$\dfrac{{Observed\,moles\,concentration}}{{Initial\,moles\,concentration}} = \dfrac{{{M _\gamma }}}{{{M _0}}}$
$\dfrac{{C\left( {1 - \alpha } \right) + \dfrac{{C\alpha }}{6}}}{C} = \dfrac{{{M _\gamma }}}{{{M _0}}} = \dfrac{{30}}{{150}}$
Hence the answer is $\alpha  = 0.96$

The monomer that undergo radical polymerisation most easily is ?

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. $CH _2=CH _2$

  2. $C _6H _5CH=CH _2$

  3. $CH _2=C{(Me)} _2$

  4. $CH _3-CH=CH _2$

Show answer
Correct Option: A

During the vinyl polymerisation, the chain transfer agent is:

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. $C{Cl} _{4}$

  2. ${C} _{6}{H} _{5}OH$

  3. t-butyl peroxide

  4. diphenylamine

Show answer
Correct Option: A
Explanation:
In the presence of $C{Cl} _{4}$ or any other chain transfer agents, the monomer polymerizes to give lower average molecular mass polymers.
Hence, the correct option is A.

Which one of the following polymer is step-growth polymer

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. Polythylene

  2. Nylon-$66$

  3. Buna-$S$ rubber

  4. Orlon

Show answer
Correct Option: A

Which of the following free radicals is the most stable ?

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. primary

  2. methyl

  3. secondary

  4. tertiary

Show answer
Correct Option: D
Explanation:

Electron poor species are stabilized by neighboring atoms that can donate electron density. The most common way to interpret rich neighbors here is the observation that increasing the number of alkyl groups on the carbon bearing the free radical increases its stability. 


Radical stability increases in the order methyl < primary < secondary < tertiary. 

Hence, option $D$ is correct.

Which of the following polymer is not an addition polymer?

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. Teflon

  2. BUNA-N

  3. PAN

  4. Propylene

Show answer
Correct Option: B
Explanation:

BUNA-N is formed by removal of water molecule so it is condensation polymer.

Which of the following are used as free radical chain initiators ?

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. Benzoyl peroxide

  2. di-tert-butyl peroxide

  3. Carbon tetrachloride

  4. Benzoquinone

Show answer
Correct Option: A,B
Explanation:

A radical initiator is a species that acts as the reactant of the initiation step of a radical chain reaction but does not participate in any of the propagation steps.
Radical initiators are substances that can produce radical species under mild conditions and promote radical reaction. These substances generally possess weak bonds that have small bond dissociation energy. Radical initiators are utilized in industrial processes such as polymer synthesis. Typical examples are halogen molecules, azo compounds and organic and inorganic peroxides such as Benzoyl peroxide, di- t-Butyl peroxide.

Which of the following polymers can be made by free radical addition polymerisation mechanism?

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. PE

  2. HDPE

  3. LDPE

  4. Telfon

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

The polymers polyethene (PE), low density polyethene(LDPE), high density polyethene(HDPE) and teflon (polytetrafluoroethylene) can be made by free radical addition polymerisation (also known as chain growth polymerisation) mechanism.  To obtain free radicals, initiators such as benzoyl peroxide, tert-butyl peroxide or acetyl peroxide are used.

Polymerisation of buta - $1,:3$ - diene by free radical mechanism gives___________.

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. trans - $1,: 4$ - Polybutadiene

  2. cis - $1, :4$ - Polybutadiene

  3. Polyvinyl polyethene

  4. Polyallyl polythene

Show answer
Correct Option: A,B,C

$\begin{bmatrix}-CH _2-\underset{\underset{\textstyle\;OH}{\displaystyle\mid}}{\;\;\;CH}-CH _2-\underset{\underset{\textstyle\;OH}{\displaystyle\mid}}{\;\;\;CH}-CH _2-\underset{\underset{\textstyle\;OH}{\displaystyle\mid}}{\;\;\;CH}-\end{bmatrix} _n$

Polyvinyl alcohol (as shown above) is a unique polymer having high affinity for water. Which of the following procedures would be most suitable for its preparation?

chemistry polymer addition polymerisation types of polymerisation reactions petrochemicals and polymers

  1. radical chain polymerisation of $CH _2=CH-CH _2-OH$

  2. radical chain polymerisation of $CH _2=CH-OH$

  3. radical chain polymerisation of $CH _2=CH-CO _2CH _3$, following by base catalysed hydrolysis

  4. radical chain polymerisation of $CH _2=CH-OCOCH _3$, followed by acid catalysed hydrolysis

  5. radical chain polymerisation of $CH _2=CH-OCOCH _3$, followed by base catalysed hydrolysis

Show answer
Correct Option: B
Explanation:

$\begin{bmatrix}-CH _2-\underset{\underset{\textstyle\;OH}{\displaystyle\mid}}{\;\;\;CH}-CH _2-\underset{\underset{\textstyle\;OH}{\displaystyle\mid}}{\;\;\;CH}-CH _2-\underset{\underset{\textstyle\;OH}{\displaystyle\mid}}{\;\;\;CH}-\end{bmatrix} _n$ 


Polyvinyl alcohol is prepared by radical chain polymerisation of  $CH _2=CH-OCOCH _3$, followed by base catalysed hydrolysis in which acetate group is replaced by hydroxide group.