Module 8 Problem Set_ Principles of Organic Chemistry with Lab-2021-Gallaher

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12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 1/11 Module 8 Problem Set Due No due date Points 10 Questions 16 Time Limit None Attempt History Attempt Time Score LATEST Attempt 1 35 minutes 10 out of 10 Score for this quiz: 10 out of 10 Submitted Dec 5 at 7:14pm This attempt took 35 minutes. Not yet graded / 0 pts Question 1 Your Answer: Define the term polymer . Polymers are large molecules made by repetitive linking of smaller units known as monomers. Answer: Polymers are large molecules made by repetitive linking of smaller units known as monomers. The terms polymer and monomer are derived from the Greek roots poly (many), mono (one), and meros (part). Not yet graded / 0 pts Question 2

12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 2/11 Your Answer: Name and describe the two main classifications of polymers. Chain-growth polymers (also known as addition polymers) are made by the addition of one monomer unit to another in a repetitive manner. Monomers for addition polymers usually contain a multiple bond (frequently a C=C) to which a reactive species can be added. Step-growth polymers (also known as condensation polymers) are formed by the reaction between two different functional groups on different monomer molecules, with the accompanying loss of some small molecule (typically water). Answer: Polymers can be classified as either natural or synthetic. Natural polymers include rubber, carbohydrates like starch or cellulose, proteins, and nucleic acids (DNA/RNA). The biologically relevant natural polymers are sometimes called biopolymers . Synthetic polymers are created by scientists in a lab (not formed in nature) for specific purposes. Synthetic polymers are generally known by the generic term “plastics” Not yet graded / 0 pts Question 3 Your Answer: What is a macromolecule ? A macromolecule is a very large molecule composed of thousands of covalently bonded atoms. Polymers can also be classified as either natural or synthetic.

12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 3/11 Answer: A macromolecule is a very large molecule composed of thousands of covalently bonded atoms. Not yet graded / 0 pts Question 4 Your Answer: Name and briefly describe the two main ways (classifications) in which polymers are made. Natural polymers include rubber, carbohydrates like starch or cellulose, proteins, and nucleic acids (DNA/RNA). The biologically relevant natural polymers are sometimes called biopolymers . Synthetic polymers are created by scientists in a lab (not formed in nature) for specific purposes. Synthetic polymers are generally known by the generic term “plastics” and include a wide variety of structures that visibly impact our daily lives, perhaps more than any other class of organic molecule. Answer: 1. Chain-growth polymers (also known as addition polymers) are made by the addition of one monomer unit to another in a repetitive manner. 2. Step-growth polymers (also known as condensation polymers) are formed by the reaction between two different functional groups on different monomer molecules, with the accompanying loss of some small molecule (typically water).

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12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 5/11 Answer: This means that the bond is broken (cleaved) so that each atom joined by the bond gets one of the two electrons in the bond. Not yet graded / 0 pts Question 7 Your Answer: Name and briefly describe the three steps of a radical chain reaction. Initiation – the production of radical species from non-radical species, typically using heat or UV light. Propagation – the reaction of a radical with a non-radical, producing a new radical species. The new radical species continues the chain reaction. Termination – the reaction of two radical species with one another, producing a non-radical species. The lack of a reactive intermediate then stops the chain reaction.. The lack of a reactive intermediate then stops the chain reaction. Answer: • Initiation – the production of radical species from non- radical species, typically using heat or UV light. • Propagation – the reaction of a radical with a non-radical, producing a new radical species. The new radical species continues the chain reaction. • Termination – the reaction of two radical species with one another, producing a non-radical species. The lack of a reactive intermediate then stops the chain reaction.

12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 6/11 Not yet graded / 0 pts Question 8 Your Answer: Name and describe the two ways by which a free-radical polymerization reaction is terminated. The lack of a reactive intermediate then stops the chain reaction. Answer: Radical coupling occurs when two radicals combine using the unpaired electron on each to make a new covalent bond. Radical disproportionation occurs when one radical abstracts (removes) a hydrogen from another radical species. The two unpaired electrons then join to form a new C=C p bond. Not yet graded / 0 pts Question 9 Your Answer: Name and briefly describe the three main stereochemical classes of polymers (tacticity). Atactic –stereocenters have random configurations. Isotactic – all stereocenters have the same configuration. Syndiotactic – stereocenters alternate in configuration. Answer: • Atactic –stereocenters have random configurations. • Isotactic – all stereocenters have the same configuration. • Syndiotactic – stereocenters alternate in configuratio n.

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12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 7/11 Not yet graded / 0 pts Question 10 Your Answer: Describe the difference between stereoregular and stereorandom polymers. Stereoregular: the configuration of their stereocenters is not random stereorandom: configuration random Answer: In a stereoregular polymer the orientation of the stereocenters formed along the polymer chain is NOT random. Not yet graded / 0 pts Question 11 Your Answer: What are the two main methods for controlling the tacticity of a growing polymer chain during synthesis? The first approach is called chain end control . Given an existing stereocenter at the end of the chain, the approach of the next monomer will be influenced by how that existing chiral center projects in space. As a result, the preceding chiral center influences how the next one is formed. Conceptually, this idea is the same as saying that in a simple organic reaction, an existing chiral center may force an incoming group to one face of a molecule rather than another, leading to preferential formation of a particular stereochemistry where the new bond is made. In the case of polymers, it means that the very first insertion reaction, when the first chiral center forms, determines all the subsequent stereochemistry along the chain.

12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 8/11 The second approach is called site control . In site control, the specific shape of the reagent or catalyst that facilitates the reaction also determines the stereochemistry. This idea is also seen in organic reactions. Reagents or catalysts will fit with the substrate in one way more easily than another, leading to preferential formation of one stereochemistry and not the other. Answer: Chain-end control and site control. Not yet graded / 0 pts Question 12 Your Answer: Describe the major difference between homopolymers and copolymers. homopolymers – those polymers composed of only a single type of monomer copolymers - polymers composed of more than one type of monomer - has been explored as a means of controlling the properties of the resulting polymer product. In this respect, it is useful to distinguish several ways in which different monomeric units might be incorporated in a polymeric molecule. Answer: Homopolymers – those polymers composed of only a single type of monomer. Copolymers - polymers composed of more than one type of monomer.

12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 9/11 Not yet graded / 0 pts Question 13 Your Answer: Name and briefly describe the different ways of arranging two different types of monomers into a copolymer. Random (statistical) copolymers: Here, the monomeric units are distributed randomly, and sometimes unevenly, in the polymer chain: Alternating copolymers : Here, the monomeric units are distributed in a regular alternating fashion, with nearly equimolar amounts of each in the chain: Answer: Random (statistical) copolymers: Here, the monomeric units are distributed randomly, and sometimes unevenly, in the polymer chain: Alternating copolymers : Here, the monomeric units are distributed in a regular alternating fashion, with nearly equimolar amounts of each in the chain: Block copolymers : Instead of a mixed distribution of monomeric units, a long sequence or block of one monomer is joined to a block of the second monomer: Graft copolymers: As the name suggests, side chains of a given monomer are attached to the main chain of the second monomer Not yet graded / 0 pts Question 14 Name the main factors affecting the properties of polymers.

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12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 10/11 Your Answer: The properties of polymers are strongly affected by their molecular weight and molecular weight distribution, as well as by their chain architecture, Answer: The properties of polymers are strongly affected by their molecular weight and molecular weight distribution, as well as by their chain architecture, particularly by the amount of branching. The effect of branching on the polymer properties depends on the number and length of the branches. Not yet graded / 0 pts Question 15 Your Answer: Define the terms amorphous, thermoplastic, and cross-linking- as they apply to polymers. Amorphous: the polymer chains are arranged in a random manne Thermoplastic: thermoplastic , meaning that it softens upon heating and hardens again upon cooling

12/14/23, 8:43 PM Module 8 Problem Set: Principles of Organic Chemistry with Lab-2021-Gallaher https://portagelearning.instructure.com/courses/1430/quizzes/35838?module_item_id=151535 11/11 Answer: Amorphous - the polymer chains are arranged in a random manner, as they are not regularly aligned as in a crystal. Thermoplastic – a polymer that softens upon heating and hardens again upon cooling. Cross-linking - a process that can form links (typically covalent bonds between growing chains of the polymer). These links serve to tether the growing chains together in a less random (more crystalline) order. Not yet graded / 10 pts Question 16 Your Answer: As a reminder, the questions in this review quiz are a requirement of the course and the best way to prepare for the module exam. Did you complete all questions in their entirety? Yes Quiz Score: 10 out of 10 This quiz score has been manually adjusted by +10.0 points.