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Chemistry learn with tricks and techniques. Free study materials of Chemistry.we try to cover. NEET, JEE, SET, Maharashtra board study materials, etc. of chemistry in free of cost.

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Friday, May 29, 2020

Introduction to polymer chemistry part - 3 & 4

Introduction to polymer chemistry part - 3

Teflon ( Polytetrafluoroethylene):
Its monomer is tetrafluoroethylene (CF2=CF2). Tetrafluoroethylene is polymerized by using free radical. Its initiators are hydrogen peroxide or ammonium persulphate.
 







Properties of Teflon:

Teflon is chemically inert, tough, & heat resistant. C – F bond is difficult to break.

Uses of Teflon:

It is used to make non-stick cookware, gaskets, oil sealant, etc.

For more detail, watch the video lecture;

➤ Introduction to polymer chemistry part - 3



Phenol – formaldehyde & related polymers:


a) Bakelite:


The monomers phenol & formaldehyde reacts in presence of acid or base as catalyst to form linear polymer called novolac in two stages.

Phenol
 
 





Formation of Novolac
 






In third stage, novolac is heating at 138 – 176oC , at high pressure where cross linking by ortho & para position of novolac occurs to form three dimensional network solid called Bakelite. & put into molds for various shape of Bakelite.


For more detail, watch the video lecture;

➤ Introduction to polymer chemistry part-4


Thursday, April 23, 2020

Polymers

1) Rubber

Rubber is the elastomer. The materials are made by rubber are balloon, tyres, surgical gloves & many more things.

Rubber includes the natural rubber & vulcanized rubber.





Natural rubber:

Natural rubber is found in the form of suspension (colloid) as a latex from the rubber tree. Latex or natural rubber is straight or linear polymer  2-methyl-1,3-butadiene also known as isoprene. Its cis configuration that is cis-1,4- polyisoprene contain long flexible chains which has more elastic property ( ability to get stretched & regain after removal of stress). Natural rubber has molecular mass in the range of 130,000u - 340,000 u.
Its trans configuration that is trans - 1,4- polyisoprene contain zig-zag chain & non - elasticity. trans isomer is found in solid form which is known as Gutta Percha.

For more detail click on the link below,

➤ Introduction to polymer chemistry part - 2
 
 
  

Wednesday, April 22, 2020

12th (New syllb.)

Saturday, April 11, 2020

Introduction to Polymer Chemistry

Introduction to Polymer Chemistry 

      Greek word polymers= Poly (many) + mers (unit / structure). First, what is monomers?
Monomers are small repeating units  combined to form macromolecules i.e. polymers.
Thus polymers is defined as, "giant macromolecules made by monomers having high molecular mass about 103 – 107 u." 
     In our day to day life we use many different kinds of polymers like bakelite, PVC, Low density polythene, high density polythene, terylene, vulcanized rubber, neoprene, cellulose, cellulose rayon, acetate rayon, jute, silk, wool, etc. they enriched the life of human being.

Classification of polymers:

      Polymers are classified into many types some of these are,
i) Polymers based on their sources
ii) Polymers based on their chemical structure
iii) Polymers based on their mode or process of polymerization
iv) Polymers based on their molecular forces 
v) Polymers based on their biodegradability

For more detail, watch the video & click on the link.
 ➤Introduction to polymer chemistry part -1

Sunday, April 5, 2020

Hydrocarbons

Hydrocarbons

Introduction

      The compound which contain only carbon & hydrogen is called hydrocarbons. HC may be open chain/ cyclic/ saturated or unsaturated / aromatic or non aromatic.
Saturated means HC contain carbon carbon single bond (C —C).
Unsaturated means HC contain carbon carbon multiple (more than one) bond (C =C or C≡C). Example: CH=CH₂; CH = CHCH; CH≡CH; ; CH CH≡CH.
Aromatic compounds means cyclic compounds similar to benzene.


Non aromatic compounds means cyclic compounds that not contain double bond like benzene.

Alkanes
      It is aliphatic saturated hydrocarbons containing carbon-carbon (CC) & carbon-hydrogen (C—H) single covalent bonds. It has a general formula CnH2n+2, where 'n' number of carbon atoms in the alkane molecule.

      Alkanes also called paraffins because they are chemically less reactive and not have much affinity to other chemicals due to their carbon-carbon and carbon-hydrogen single covalent bonds.


Isomerism

      Iso Greek word which means same & mers means unit or structure. Alkanes having same chemical formula but different in structure that compounds is called isomers & phenomena is called isomerism.


Isomerism in Alkanes


Alkanes having more than three carbon atoms exhibits, structural isomerism i.e. chain isomerism. Chain isomerism in CH₁₀ & CH₁₂ is as follow,

 




















Conformation in alkanes


            If the isomers are nonconvertible by rotation about carbon – carbon single bond, the isomers are called conformers & phenomena are called conformation. Conformation is a type of stereo isomerism.

            Ethane or higher alkane by carbon – carbon single bond rotation about every 60o produces new conformation like staggered, eclipsed, gauche conformation.
            Staggered conformation is more stable than eclipsed because less energy required to rotate the bond & less or no repulsion between bonds in staggered conformation.