Year 10 Chemistry: Detailed Explanation of Addition and Condensation Polymerisation

Detailed Explanation of Addition and Condensation Polymerisation 🧪

What is Polymerisation? 🔗

Polymerisation is the chemical process of joining many small molecules called monomers together to form a large molecule called a polymer. Polymers are found in everyday materials such as plastic bottles, clothing fibres, and even some natural substances.

Addition Polymerisation ➕

Addition polymerisation happens when many identical monomers with double bonds join together without losing any atoms. This process mainly involves alkenes (hydrocarbons with carbon-carbon double bonds).

• Definition: Addition polymerisation is a reaction where unsaturated monomers (containing double bonds) open up their double bonds and link together to form a long chain polymer.
• Process:
  1. The double bonds in the monomers break.
  2. These monomers link together, forming a long chain without producing any by-products.
• Example: Ethene (C₂H₄) monomers join to make polyethene (polyethylene), a common plastic used in bags and bottles.

Equation example:
n CH2=CH2 → (CH2-CH2)n

Here, the double bonds in ethene break, and the molecules link to form polyethene.

Condensation Polymerisation 🌊

Condensation polymerisation is different. It usually happens between two different types of monomers with two reactive ends, forming a polymer and producing a small molecule like water as a by-product.

• Definition: Condensation polymerisation is the process where monomers with two different functional groups join together, releasing small molecules such as water, ammonia, or hydrogen chloride.
• Process:
  1. Two different monomers react.
  2. Each time they join, a small molecule (like water) is released.
  3. This continues to form long chain polymers.
• Example: When a dicarboxylic acid reacts with a diol, they form a polyester polymer and release water. Another example is nylon, formed from diamines and dicarboxylic acids.

Equation example:
Ethane-1,2-diol + Hexanedioic acid → Polyester + Water

Main Differences Between Addition and Condensation Polymerisation ⚖️

Summary 📝

• Addition polymerisation involves breaking double bonds in monomers to form polymers with no by-products.
• Condensation polymerisation joins two different monomers with the release of small molecules like water.
• Knowing the differences helps you understand how different types of plastics and fibres are created.

Understanding these two types of polymerisation processes is key for key stage 4 Chemistry and forms a foundation for further study in materials science. Keep practising by writing out the equations and recognising examples to build confidence! 🚀

10 Examination-Style 1-Mark Questions with 1-Word Answers: Addition and Condensation Polymerisation ❓

1. What type of polymerisation involves monomers joining without losing atoms?
   Answer: Addition
2. Which gas is often released during condensation polymerisation?
   Answer: Water
3. What functional group is commonly found in the monomers for condensation polymerisation?
   Answer: Carboxyl
4. What kind of bond forms between monomers in addition polymerisation?
   Answer: Covalent
5. Name the simplest alkene used in addition polymerisation.
   Answer: Ethene
6. In condensation polymerisation, how many functional groups does each monomer usually have?
   Answer: Two
7. Which process forms polymers by opening double bonds in monomers?
   Answer: Addition
8. What is the repeating unit in a polymer called?
   Answer: Monomer
9. Condensation polymerisation typically forms which type of polymer?
   Answer: Polyester
10. What is the name of the reaction that joins monomers with loss of small molecules?
    Answer: Condensation

10 Examination-Style 2-Mark Questions with 1-Sentence Answers on Addition and Condensation Polymerisation 📚

1. What is addition polymerisation?
   Addition polymerisation is a reaction where monomers with carbon-carbon double bonds join together without losing any atoms to form a polymer.
2. Give an example of a monomer used in addition polymerisation.
   Ethene is a common monomer used in addition polymerisation to form poly(ethene).
3. What type of bond is broken to start addition polymerisation?
   The carbon-carbon double bond in the monomer breaks during addition polymerisation to form single bonds in the polymer chain.
4. Explain condensation polymerisation in one sentence.
   Condensation polymerisation involves monomers joining together with the loss of a small molecule, usually water.
5. Name two types of monomers involved in condensation polymerisation.
   Dicarboxylic acids and diols are common monomers used in condensation polymerisation.
6. What small molecule is typically lost during condensation polymerisation?
   Water is typically lost as a small molecule during condensation polymerisation.
7. Give an example of a polymer formed by condensation polymerisation.
   Nylon is an example of a polymer formed by condensation polymerisation.
8. How do addition and condensation polymerisation differ in terms of atom loss?
   Addition polymerisation does not lose any atoms, while condensation polymerisation loses small molecules like water.
9. Why are polyesters classified as condensation polymers?
   Polyesters form through condensation reactions where water is lost as monomers, such as dicarboxylic acids and diols, join together.
10. Describe the repeating unit in addition polymerisation.
    The repeating unit in addition polymerisation is the original monomer’s structure with the double bond converted into single bonds, forming a continuous chain.

10 Examination-Style 4-Mark Questions with 6-Sentence Answers on Addition and Condensation Polymerisation 🧑‍🎓

Question 1
Define addition polymerisation.

Answer:
Addition polymerisation is a chemical process where many small molecules called monomers join together to form a large molecule called a polymer. The monomers in addition polymerisation have a carbon–carbon double bond (C=C) that opens up to link with other monomers. No other molecules are produced as by-products during this type of polymerisation. The repeating unit formed is identical to the original monomer structure but joined in a long chain. This process requires an initiator or catalyst to start the reaction. Addition polymerisation is used to make polymers like poly(ethene) and poly(propene).

Question 2
Explain what condensation polymerisation involves.

Answer:
Condensation polymerisation is a chemical reaction where two different types of monomers join to form a polymer and, at the same time, a small molecule like water or HCl is produced as a by-product. Usually, these monomers have two different reactive groups, such as -COOH (carboxyl) and -OH (hydroxyl). When they react, they form a covalent bond linking the monomers and release a small molecule. This process can produce polymers such as polyesters and polyamides. Unlike addition polymerisation, condensation involves the loss of molecules during the reaction. This type of polymerisation is important for making fibres like nylon and natural polymers like proteins.

Question 3
Describe the difference between addition and condensation polymerisation.

Answer:
The main difference is that in addition polymerisation, monomers simply add together without losing any atoms, while in condensation polymerisation, small molecules like water are lost as by-products. Addition polymerisation uses monomers with double bonds, but condensation polymerisation uses monomers with two different functional groups. Addition polymers consist of one type of repeating unit, but condensation polymers are made from two different monomers. The products and mechanisms are different, with condensation polymers often forming stronger bonds like esters and amides. Understanding these differences helps in identifying polymers and how they are made.

Question 4
Give an example of an addition polymer and explain its structure.

Answer:
Poly(ethene) is an example of an addition polymer. It is made from ethene monomers, which contain a carbon–carbon double bond. During polymerisation, the double bond breaks, allowing the ethene molecules to join in a long chain. The repeating unit consists of -CH₂-CH₂– groups connected together. This polymer chain is flexible and can be shaped into various products like plastic bags and containers. The structure of poly(ethene) is simple but very useful because it is strong and resistant to chemicals.

Question 5
Explain how polyesters are formed using condensation polymerisation.

Answer:
Polyesters are formed through condensation polymerisation between monomers containing -COOH (carboxyl) groups and -OH (hydroxyl) groups. When these monomers react, an ester bond (-COO-) forms, linking the monomers together into a polymer chain. During this reaction, a molecule of water is released for each bond formed. This process repeats to form long polyester chains like Terylene. Polyesters are useful because they are strong and resistant to stretching and shrinking. They are commonly used in clothing and plastic bottles.

Question 6
What are monomers, and why are they important in polymerisation?

Answer:
Monomers are small molecules that can join together chemically to form large molecules called polymers. They are the building blocks of polymers. In addition polymerisation, monomers usually contain double bonds that open to connect with other monomers. In condensation polymerisation, monomers have different reactive groups that form bonds and release small molecules. Without monomers, polymerisation cannot occur because the polymer chain is made from repeating monomer units. Understanding monomers helps explain the structure and properties of the resulting polymer.

Question 7
Why is water produced in condensation polymerisation but not in addition polymerisation?

Answer:
Water is produced in condensation polymerisation because the reaction involves joining two different monomers that have reactive groups like -OH and -COOH. When these groups react, they form a covalent bond and release water as a by-product. In contrast, addition polymerisation only involves breaking double bonds in monomers, linking them without any atoms lost or by-products formed. The types of bonds and groups in condensation mean water or other small molecules are expelled during polymer formation. This difference in chemical reactions causes water to be present only in condensation polymerisation.

Question 8
Describe the role of the double bond in addition polymerisation.

Answer:
The double bond (C=C) in monomers is crucial for addition polymerisation because it is reactive and can open up to link with other monomers. When the double bond breaks, each carbon atom forms a new single bond with another monomer, creating a long chain. This process happens repeatedly with many monomers, producing a polymer. Without the double bond, the monomers would not be able to join easily in addition polymerisation. The breaking of the double bond is what starts and drives the reaction forward. Hence, the double bond is the key feature that allows addition polymerisation to occur.

Question 9
Explain how polyamides are made by condensation polymerisation.

Answer:
Polyamides are formed by condensation polymerisation between monomers containing -COOH (carboxyl) groups and -NH₂ (amine) groups. When these groups react, an amide bond (-CONH-) is formed, linking the monomers into a polymer chain. Each time an amide bond forms, a molecule of water is released as a by-product. This process repeats, forming long chains of polyamide, such as nylon. Polyamides have strong hydrogen bonds between chains, giving them high strength and durability. These properties make polyamides useful for textiles and engineering plastics.

Question 10
What properties of addition polymers make them useful in everyday life?

Answer:
Addition polymers like poly(ethene) are lightweight, strong, and resistant to water and chemicals. These properties make them ideal for containers, packaging, and pipes. They are also flexible and easy to shape when heated, which helps in manufacturing various products. Because they do not absorb water, they are good for storing food and liquids. Addition polymers can also be made transparent or coloured, adding to their versatility. These useful properties explain why addition polymers are so widely used in everyday life.

10 Examination-Style 6-Mark Questions with 10-Sentence Answers on Addition and Condensation Polymerisation for Year 10 Chemistry 📖

Question 1:
Explain what is meant by addition polymerisation.

Addition polymerisation is a process in which many small molecules called monomers join together to form a large molecule called a polymer. In addition polymerisation, the monomers have a carbon-carbon double bond (C=C) that breaks during the reaction. Each monomer’s double bond opens up allowing them to link together in a long chain. No other small molecules are lost in this type of polymerisation. The repeating unit in the polymer is identical to the monomer but linked by single bonds. Addition polymers are usually formed from alkenes such as ethene or propene. This reaction occurs under certain conditions, often with the help of a catalyst or heat. The resulting polymer has properties like strength and flexibility depending on the monomer used. Examples of addition polymers include polyethene and polypropene. Addition polymerisation is important for making many everyday plastics.

Question 2:
Describe the process of condensation polymerisation and how it differs from addition polymerisation.

Condensation polymerisation involves monomers reacting together to form polymers with the loss of small molecules like water or hydrogen chloride. Unlike addition polymerisation, condensation requires two different types of monomers, each having two reactive groups. These groups react and bond to form the polymer chain, but each bond formation releases a small molecule as a by-product. The polymer formed has repeating units derived from the two monomers joined together. An example is the formation of nylon from diamine and dicarboxylic acid monomers. Condensation polymers often contain ester or amide linkages. This contrasts with addition polymers, which form by opening double bonds without losing atoms. Condensation polymerisation generally needs special conditions like heat or catalysts. It produces polymers used in fibres, plastics, and adhesives. This process is slower and more complex than addition polymerisation.

Question 3:
Give two examples of addition polymers and explain their everyday uses.

Two common examples of addition polymers are polyethene and polypropene. Polyethene is made from ethene monomers and is widely used in plastic bags, bottles, and food packaging. It is light, flexible, and waterproof, making it ideal for these products. Polypropene is made from propene monomers and is tougher and more heat resistant than polyethene. It is used in items like ropes, carpets, and plastic containers. Both polymers result from addition polymerisation where monomers with double bonds join without by-products. Their properties depend on the arrangement of the polymer chains and the type of monomer used. These plastics are cheap to produce and can be easily shaped. Because of their durability and versatility, these addition polymers are found in nearly every home. However, recycling these plastics can be challenging.

Question 4:
Explain the significance of the small molecules lost in condensation polymerisation reactions.

In condensation polymerisation, small molecules like water or hydrogen chloride are lost during the reaction when monomers join. These molecules are formed because the reactive groups on the monomers bond by removing atoms. For example, when a carboxylic acid group reacts with an alcohol group, a water molecule is released as the ester bond forms. This loss of small molecules is a key difference from addition polymerisation, where no atoms are lost. The small molecule by-products show that a new compound is formed through condensation. Their removal often drives the reaction forward, helping the polymer chains to build up. These molecules can sometimes be collected and reused in industry. The presence of by-products means condensation polymerisation may need removal methods and careful control. This process is essential for making polyesters and nylons. Understanding the by-products helps chemists design efficient manufacturing processes.

Question 5:
What are the repeating units in addition and condensation polymers?

The repeating units in polymers are the small segments that repeat many times to form the polymer chain. In addition polymers, the repeating unit is the original monomer minus the double bond. The double bond opens during polymerisation, and the monomers link end-to-end without losing atoms. For example, in polyethene, the repeating unit is –CH₂–CH₂– from ethene. In condensation polymers, the repeating unit contains parts of two different monomers joined together. This unit includes the functional groups that have reacted and often contains ester or amide linkages. For instance, in polyester, the repeating unit comes from an acid and an alcohol monomer joined by an ester bond. The repeating unit in condensation polymers usually results in loss of a small molecule. Repeating units determine the chemical and physical properties of the polymer. Both types of polymers form long chains through repetition of these units.

Question 6:
How does the structure of addition polymers affect their physical properties?

The structure of addition polymers influences their strength, flexibility, and melting point. The polymer consists of long chains formed by linking monomers with single bonds. If the chains are very long and straight, they can pack closely and form strong intermolecular forces, leading to tough, rigid materials. On the other hand, branched chains cannot pack so tightly, making the polymer more flexible and softer. The regularity of the repeating units also affects crystallinity and density. For example, high-density polyethene has straight chains while low-density polyethene has branches. Some addition polymers can be strong and rigid, such as polyethene used in containers, while others like PVC are more flexible. The molecular weight (length of chains) also affects properties like melting temperature. The type of monomer changes chain interactions and therefore physical properties. Understanding structure-property relationships helps design polymers for specific uses.

Question 7:
Compare the monomers used in addition polymerisation with those in condensation polymerisation.

Monomers used in addition polymerisation are usually unsaturated molecules with at least one carbon-carbon double bond. These are often alkenes like ethene or propene. Their double bonds open up during polymerisation allowing the molecules to link directly. No atoms are lost, and the polymer is just a long chain of monomer units. In condensation polymerisation, monomers have two reactive end groups, such as –OH (alcohol), –COOH (carboxylic acid), or –NH₂ (amine). These groups react with each other, forming bonds and releasing small molecules such as water. Usually two different monomers combine in condensation polymerisation, each providing one type of reactive group. This difference means condensation monomers are often more complex molecules compared to simple alkenes. The choice of monomer controls the type of polymer and its properties. Both types of monomers are carefully designed for the intended polymer.

Question 8:
Explain why addition polymerisation does not produce small molecule by-products.

Addition polymerisation happens when monomers with double bonds link together without breaking apart any molecules. The carbon-carbon double bond in the monomers opens up, allowing them to join in a chain. Because the atoms from the monomers are simply rearranged into a polymer, there are no atoms lost or released as small molecules. This means no water, hydrogen chloride, or any other by-products are produced. The polymer chain is a repetition of the monomer units joined by single bonds. This contrasts with condensation polymerisation, where each bond formation releases a small molecule. Addition polymerisation is usually faster and simpler because there are no by-products to remove. This property makes it useful for making large volumes of plastic quickly. No extra chemicals need to be collected or recycled after the reaction.

Question 9:
Describe the role of functional groups in condensation polymerisation.

Functional groups are specific groups of atoms in monomers responsible for reaction during condensation polymerisation. Common functional groups include carboxylic acids (–COOH), alcohols (–OH), and amines (–NH₂). These groups can react with each other to form bonds, such as ester bonds (from acid and alcohol) or amide bonds (from acid and amine). The reaction forms the polymer chain and releases a small molecule like water. The presence of two reactive functional groups per monomer allows the molecules to link into long chains or networks. The type of functional groups present determines the type of polymer formed. For example, polyesters form from acid and alcohol groups, while polyamides form from acid and amine groups. Functional groups also affect the physical and chemical properties of the polymer. Understanding these helps chemists create polymers for specific uses.

Question 10:
How can the properties of polymers be changed by altering their monomers or structure?

The properties of polymers depend on the type of monomers and the way the polymer chains are arranged. Changing the monomer can introduce different functional groups, affecting strength, flexibility, and melting point. For example, adding a bulky group can make the polymer less dense and more flexible. The structure of the polymer chains, such as how straight or branched they are, changes how closely the chains pack. Closely packed chains form strong polymers with higher melting points. Introducing cross-links between chains makes the polymer tougher and less stretchable. The length of the polymer chains (molecular weight) also affects properties; longer chains usually give stronger materials. This is why different plastics have various uses, from flexible packaging to rigid containers. Chemists design polymers to meet specific needs by selecting suitable monomers and controlling polymerisation conditions. This control allows the development of plastics for many practical applications.