GCSE Chemistry - Addition Polymers & Polymerisation #56

Cognito
17 Mar 202007:10
EducationalLearning
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TLDRIn this video, we explore the process of making addition polymers using alkenes, focusing on drawing monomers, repeating units, and polymers. The video explains the significance of carbon-carbon double bonds in alkenes, how these bonds break to form polymers, and how to represent these reactions efficiently. It covers the steps to redraw alkenes for polymerization, details the notation for monomers and repeating units, and explains polymer naming conventions. The video also highlights the conditions required for addition polymerization reactions, including high pressures and catalysts.

Takeaways
  • 😀 Alkenes have a carbon-carbon double bond, making them unsaturated.
  • 😀 Under the right conditions, the double bond in alkenes can break and form new bonds.
  • 😀 Addition polymers are formed when alkenes like ethene combine to form long chains.
  • 😀 Drawing all monomers in a polymerization reaction can be tedious, so we often use repeating units.
  • 😀 Repeating units contain the same group of atoms as the original monomer and are easier to draw.
  • 😀 It's important to draw the bonds of the monomer facing up and down and the bonds of the repeating unit facing out through the brackets.
  • 😀 The variable 'n' represents the number of monomers and repeating units in the reaction.
  • 😀 To draw the polymerization of butane, identify and arrange the double bond and attached groups correctly.
  • 😀 Naming polymers is straightforward: add 'poly' before the monomer's name.
  • 😀 Addition polymerization reactions require high pressures and a catalyst.
Q & A

  • What is the characteristic feature of alkenes that makes them suitable for forming addition polymers?

    -The characteristic feature of alkenes is the presence of a carbon-carbon double bond, which allows them to undergo addition reactions to form polymers.

  • What is the term used to describe molecules like ethene that have a carbon-carbon double bond?

    -Molecules with a carbon-carbon double bond are referred to as 'unsaturated' because they can undergo addition reactions.

  • How can the double bond in alkenes be represented in a chemical reaction diagram?

    -The double bond in alkenes can be represented by showing two lines between the two carbon atoms involved in the bond.

  • What is the process called when alkenes combine to form a long chain molecule?

    -The process is called 'polymerization', specifically 'addition polymerization' when it involves alkenes.

  • Why is it impractical to draw out every monomer in a polymerization reaction involving many monomers?

    -Drawing out every monomer in a reaction involving hundreds of monomers would be time-consuming and impractical, hence a simplified representation is used.

  • What is meant by 'repeating units' in the context of polymers?

    -Repeating units refer to the group of atoms that are repeated throughout the polymer chain, containing the same group of atoms as the monomer.

  • How should the bonds of a monomer be drawn when writing out polymerization equations?

    -The bonds of the monomer should be drawn facing up and down rather than at angles to simplify the representation.

  • What is the significance of the 'n' in the repeating unit representation of a polymer?

    -The 'n' signifies the number of monomers, and thus the number of repeating units, involved in the polymerization reaction.

  • How is the polymer named when it is formed from a specific monomer?

    -The polymer is named by placing the word 'poly' in front of the monomer's name, with the monomer's name in brackets.

  • What are the typical conditions required for addition polymerization reactions to occur?

    -Addition polymerization reactions typically require high pressures and a catalyst to proceed.

  • Can you provide an example of how to write the polymerization equation for a four-carbon alkene like butene?

    -To write the equation, first redraw the butene molecule with the double bond in the center and arrange the atoms in separate groups above and below the double-bonded carbons. Then, simplify any complex groups, add brackets to represent the repeating unit, and indicate the reaction arrow and conditions if necessary.

Outlines
00:00
🌟 Understanding Alkene Polymerization

This paragraph introduces the concept of addition polymerization using alkenes, focusing on the representation of monomers, repeating units, and the resulting polymers. Alkenes, characterized by carbon-carbon double bonds, can undergo polymerization when these double bonds break and form new bonds with adjacent molecules, creating long-chain polymers. The script explains two methods of representing this process: a detailed method showing all monomers and a simplified method highlighting a single monomer and repeating unit. Key points for drawing these structures are discussed, including the orientation of bonds and the significance of the 'n' value in indicating the number of monomers and repeating units involved in the reaction.

05:02
📝 Step-by-Step Polymerization Equation Writing

The second paragraph provides a step-by-step guide on how to write an equation for the addition polymerization of a four-carbon alkene, using butane as an example. It details the process of redrawing the butane molecule to align with the standard format for depicting polymerization, which includes arranging atoms in groups directly above and below the double-bonded carbons. The paragraph also explains how to simplify complex groups into shorthand notation and emphasizes the importance of drawing carbon-to-carbon bonds correctly. Following this, the script describes how to add brackets and the 'n' value to represent the repeating unit and how to write the reaction arrow. The naming convention for polymers is introduced, with 'poly' prefixed to the monomer's name in brackets. The paragraph concludes by mentioning the necessity of high pressures and a catalyst for addition polymerization reactions, which may be indicated on the reaction arrow.

Mindmap
Keywords
💡Alkenes
Alkenes are a class of hydrocarbons with at least one carbon-carbon double bond. They are referred to as 'unsaturated' due to the presence of this double bond, which allows for further chemical reactions such as polymerization. In the script, alkenes are the starting materials for the formation of addition polymers, with ethene being used as an example to illustrate the process.
💡Carbon-Carbon Double Bond
A carbon-carbon double bond is a covalent bond between two carbon atoms, consisting of four electrons shared between them. This bond is a key feature of alkenes and is the site where polymerization reactions typically occur. The script explains that the double bond can break and reform, allowing the formation of new bonds with other molecules, which is essential for creating polymers.
💡Monomers
Monomers are the small molecules that can chemically bond together to form a larger molecule called a polymer. In the context of the video, ethene molecules serve as monomers that combine to form a polymer through the opening of their double bonds. The script uses the term to describe the individual units that participate in the polymerization reaction.
💡Polymers
Polymers are large molecules composed of repeating structural units derived from monomers. In the script, the process of creating polymers from alkenes is the main focus, with the example of ethene molecules combining to form a long chain, which is then referred to as a polymer.
💡Unsaturated
The term 'unsaturated' in chemistry refers to molecules that have one or more double or triple bonds between atoms, allowing for additional chemical reactions to occur. In the video script, alkenes are described as unsaturated because of their carbon-carbon double bonds, which is what enables them to participate in polymerization reactions.
💡Repeating Units
Repeating units are the structural elements of a polymer that are repeated along the length of the polymer chain. The script explains that these units contain the same group of atoms as the monomer and are crucial for understanding the structure of the resulting polymer.
💡Polyethylene
Polyethylene is a common type of polymer made from the monomer ethene. The script mentions it as an example of a polymer that is formed through the addition polymerization of ethene, where the double bonds in ethene molecules open up and link together to form a long chain.
💡Addition Polymerization
Addition polymerization is a type of chemical reaction where monomers with double or triple bonds add to each other to form a polymer. The script describes this process in detail, showing how the double bonds in alkenes can break and reform to create a polymer chain.
💡Catalyst
A catalyst is a substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change. In the context of the video, a catalyst is required for the addition polymerization reaction to proceed efficiently. The script mentions that these reactions typically require high pressures and a catalyst.
💡Polybutane
Polybutane is the polymer formed from the monomer butane, as illustrated in the script. The term is formed by prefixing 'poly' to the name of the monomer, indicating the polymer's composition and structure.
💡Polychloroethylene
Polychloroethylene is mentioned in the script as an example of a polymer that could be formed from the monomer chloroethene. Similar to polybutane and polyethylene, the name indicates the monomer from which the polymer is derived.
Highlights

In today's video, we're going to look at how to make addition polymers using alkenes.

The feature that makes a molecule an alkene is the carbon-carbon double bond.

Alkenes are unsaturated because they have a carbon-carbon double bond.

Under the right conditions, the double bond can break into a single bond, allowing the carbons to form new bonds.

Ethene molecules can form new bonds with each other to create a polymer chain.

A better way to represent polymerization is by showing a single monomer and a single repeating unit.

Repeating units in a polymer contain the same group of atoms as in the monomer.

When drawing monomers, the bonds should face up and down, while in repeating units, empty bonds point left and right through brackets.

The 'n' in polymer equations indicates the number of repeating units.

For butane polymerization, identify and rearrange the atoms around the double bond.

Simplify groups of atoms, like converting C2H5 to a shorthand, to make drawing easier.

Name polymers by putting 'poly' in front of the monomer's name, such as polyethylene or polybutane.

Addition polymerization reactions require high pressures and a catalyst.

Understanding these principles helps in writing accurate polymerization equations.

This video covered key concepts of addition polymerization, aiming to make them understandable.

Transcripts

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Polymer ChemistryAlkene ReactionsChemical BondingAddition PolymersEthene MonomersPolymerization ProcessChemistry TutorialMolecular StructureEducational ContentScience Education