Chemistry: Organic Chemistry: Polymerization Reactions
How monomers join to form addition and condensation polymers
Chemistry: Organic Chemistry: Polymerization Reactions
How monomers join to form addition and condensation polymers
Chemistry - Grade 9-12
- 1
Ethene, CH2=CH2, can form polyethene through an addition polymerization reaction. Write the repeating unit of polyethene and explain what happens to the carbon-carbon double bond.
The atoms in the monomer are not lost in addition polymerization.
The repeating unit of polyethene is -CH2-CH2-. During addition polymerization, the carbon-carbon double bond in each ethene monomer opens and forms new single bonds to neighboring monomers. - 2
Classify the formation of polypropene from propene, CH2=CHCH3, as addition polymerization or condensation polymerization. Explain your choice.
The formation of polypropene from propene is addition polymerization because the propene monomers join by opening their carbon-carbon double bonds and no small molecule such as water is produced. - 3
Nylon-6,6 forms when hexane-1,6-diamine reacts with hexanedioic acid. A small molecule is released each time an amide bond forms. Identify the type of polymerization and name the small molecule released.
A carboxylic acid group reacting with an amine group forms an amide bond.
This is condensation polymerization because the monomers join while releasing a small molecule. The small molecule released is water. - 4
Vinyl chloride has the structure CH2=CHCl. Draw or describe the repeating unit of polyvinyl chloride, PVC.
The repeating unit of PVC is -CH2-CHCl-. The chlorine atom remains attached to one carbon in each repeating unit. - 5
Explain the difference between a monomer and a polymer using styrene and polystyrene as examples.
The prefix poly means many.
A monomer is a small molecule that can join with many similar molecules. Styrene is a monomer, and polystyrene is a polymer made of many styrene repeating units connected in a long chain. - 6
A polymer is formed from the monomer tetrafluoroethene, CF2=CF2. The product is polytetrafluoroethene, PTFE. Write the repeating unit and identify the polymerization type.
The repeating unit is -CF2-CF2-. The reaction is addition polymerization because the carbon-carbon double bond opens and the monomers join without eliminating a small molecule. - 7
A polyester can form when a diol reacts with a dicarboxylic acid. What functional group forms in the polymer chain, and why is this reaction considered condensation polymerization?
A carboxylic acid and an alcohol can react to make an ester.
An ester functional group forms in the polymer chain. The reaction is condensation polymerization because each ester bond forms with the release of a small molecule, usually water. - 8
The diagram shows three propene monomers joining to begin a polypropene chain. Describe the repeating unit of polypropene in words or symbols.
The repeating unit of polypropene is -CH2-CH(CH3)-. Each repeating unit has a methyl group, CH3, attached to every other carbon in the main chain. - 9
Compare addition polymerization and condensation polymerization in terms of reactants and products.
Think about whether anything besides the polymer is made.
Addition polymerization usually uses unsaturated monomers with carbon-carbon double bonds and produces only the polymer. Condensation polymerization usually uses monomers with two functional groups and produces a polymer plus a small molecule such as water or hydrogen chloride. - 10
A student says, "All polymerization reactions make water." Explain why this statement is incorrect.
The statement is incorrect because addition polymerization does not make water or another small molecule. Only many condensation polymerization reactions release water or a similar small molecule when the monomers join. - 11
Polyethylene terephthalate, PET, is a polyester used in many plastic bottles. It forms from a diol and a dicarboxylic acid or related ester. Identify PET as an addition polymer or a condensation polymer and explain your reasoning.
Look for ester linkages in the polymer chain.
PET is a condensation polymer because it contains ester linkages formed when difunctional monomers join. The formation of these linkages involves the loss of small molecules such as water or methanol, depending on the starting materials. - 12
The image shows a section of a polymer chain with the repeating pattern -CH2-CH2-CH2-CH2-. Identify a possible monomer that could have formed this polymer by addition polymerization and explain your answer.
A possible monomer is ethene, CH2=CH2. When ethene molecules undergo addition polymerization, their double bonds open and connect to form a chain with the repeating unit -CH2-CH2-.