(b) Compute the number-average molecular weight for a polystyrene for which the degree of polymerization is 25,000. Answer with step by step detailed solutions to question from Arihant's BITSAT Prep Guide, Polymers- "Repeating unit of polystyrene is" plus 6299 more questions from Chemistry. The molecular mass of the repeat unit, MR, is simply the sum of the atomic masses of the atoms within the repeat unit. Here's an example: We notice that the repeating unit is linked to the rest of the chain by amide functional groups, and that the repeating unit contains an amide group. Thus, the molecular weight of the styrene repeat unit is: m s = 8(A C) + 8(A H) = 8(12.01 g/mol) + 8(1.008 g/mol) = 104.14 g/mol Let f b be the chain fraction of butadiene repeat units. constitutes the repeating units. Isotactic polystyrene is said to be highly crystalline. "Mer" originates from the Greek word "meros," which means a part. repeating unit. Polystyrene is a synthetic aromatic polymer made from the monomer styrene. Polymer molecules are very large compared with most other molecules, so the idea of a repeat unit is used when drawing a displayed formula. HDPE is composed of macromolecules in which n ranges from 10,000 to … Join Yahoo Answers and get 100 points today. (a) Draw the structure of the repeating unit in the superglue polymer. The examples of homopolymer are: polystyrene, polyethylene, polyvinyl chloride. (b) Compute the number-average molecular weight for a polystyrene for which the degree of polymerization is 25,000. Polyethylene may be considered either as -[CH2-CH2-]n- with a repeat unit of -[CH2-CH2]-, or as [-CH2-]n-, with a repeat unit of -[CH2]-. When drawing one, you need to: Other than monodisperse polymers, there is normally a molar mass distribution caused by chains of different length. On the basis of structure of polymers, they can be, The correct classification of polymers based on, Synthetic polymer prepared by using caprolactam is, Relation between number of av er age molecular mass, The structural formula of monomer of poly methyl, $ Nylon $-66 B=$ Buna $-S,C=$ olyethene, Arrange these in the increasing order of their. The molecular mass of the chain is just the product nMR. We connect students with top tutors from the IITs and BITS - instantly, anytime, anywhere. 552450.0 g/mol. Chemistry; Thread starter AndrewDe; Start date Sep 27, 2017; Sep 27, 2017 #1 AndrewDe. Polystyrene. constitutes the repeating units. Since there are only two repeat unit types in the copolymer, the chain fraction of styrene repeat units f s is 1 – f b. The repeating structural unit of most simple polymers not only reflects the monomer(s) from which the polymers are constructed, but also provides a concise means for drawing structures to represent these macromolecules. We serve Class 8th - 12th students preparing for CBSE, ICSE and State boards as well as all entrance exams such as IIT JEE Main & Advanced, BITSAT, NEET, VITEEE, MU OET, SRMEEE, AIPMT and all State entrance exams. General-purpose polystyrene is clear, hard, and rather brittle. For example, polystyrene chains may be grafted onto polybutadiene, a synthetic rubber which retains one reactive C=C double bond per repeat unit. There are usually between 104 to 106 repeating units in a chain C C C C C C CH3 H H H CH3 H H H CH3 H H H be able to recognise the repeating unit in a poly(a lkene) Poly(a lkenes) like alkanes are unreactive due to the strong C-C and C-H bonds Monomer Polymer n ... Poly(phe nylethene) also known as polystyrene C C H H H phenylethene The phenyl group is -C6H5 See chapter 6.9 on … The subscript "n" denotes the degree of polymerisation, that is, the number of units linked together. i know the answer is 1.1515 x 10^4 but how is it? Out of the total production of styrene, about 50% is used to produce polystyrene, about 20% to elastomers, polymer dispersions and thermosetting resins, 15% to produce ABS and SAN copolymers, 10% in expanded polystyrene (EPS), and the rest is for the production of various copolymers and specialty materials. The aqueous sample is pumped by a HPLC pump from the sample vial through the extraction cell and … What is the value of n if the molecular mass of a single polymer chain is 1.5782 x 106 amu? [2], An atom or group of atoms (with pendant atoms or groups, if any) comprising a part of the essential structure of a macromolecule, an oligomer molecule, a block or a chain. The condensation involves loss of water, as an H is lost from each HO- group in the glycol, and an OH from each HOOC- group in the acid. how big … 14.4 (a) Compute the repeat unit molecular weight of polystyrene. Thus, m = 8(A C) + 8(A H) = (8)(12.01 g/mol) + (8)(1.008 g/mol) = 104.14 g/mol (b) We are now asked to compute the number-average molecular weight. A polymer can be a 3-dimensional (3D) network Imagine of a repeating unit joined together left and right, back and front, up and down or it is a 2-dimensional (2D) network Imagine of the repeating units linked together right, left, down, and up in a sheet or a 1-dimensional (1D) network Imagine of a repeating unit … Dacron consists of polymerized units of the monomer ethylene terephthalate, with repeating (C 1 0 H 8 O 4 ) units. Given that the atomic weight of carbon and hydrogen is 12.01 g/mol and 1.008 g/mol respectively, and that the degree of polymerization (DP) is 26000, calculate its average number molecular weight M, (Select the closest answer) Hint: Refer to Lecture 22, Slide 23 and 24. The simplest way to understand the term polymer is a beneficial chemical made of many repeating units. units. (a) Compute the repeat unit molecular weight of polystyrene. I'm trying to calculate the unit molecular weight of polystyrene. A copolymer consists of two or more different monomers as repeating units, such as the diblock copolymer: and the random or static copolymer: An example is the polystyrene-poly(methyl methacrylate) copolymer. Trending questions. Source(s): https://owly.im/a8y7V. For polystyrene, from Table 14.3, each repeat unit has eight carbons and eight hydrogens. Under the influence of polymerization catalysts, the double bond can be broken and the resultant extra single bond used to link to a carbon atom in another ethylene molecule. Solution for The repeat unit in polystyrene coffee cup has C6H5CHCH2. A collection of products made from polystyrene: a cup, a guitar case, polystyrene carvings, and floating pool noodles. (ii) Compare and contrast the polymer formed in Reaction 5 to the polymer formed in Reaction 3. polystyrene, from Table 5.3, each repeat unit has eight carbons and eight hydrogens. For polyethylene, arguably the simplest polymer, this is demonstrated by the following equation. The incredible insulating capabilities of polystyrene can maintain the temperature hot or cold. HashLearn is the #1 platform to get online coaching for competitive exams. Bakelite is obtained from phenol by re acting it with. In your answer you should explain why the polymers formed in these two reactions are different. (b) The polymer shown above contains methyl groups (CH 3). constitutes the repeating units. Constitutional repeating unit (CRU), A repeat unit is sometimes called a mer or mer unit. Here's an example: We notice that the repeating unit is linked to the rest of the chain by amide functional groups, and that the repeating unit contains an amide group. Did you know? Solid polystyrene is transparent, owing to these large, ring-shaped molecular groups, which prevent the polymer chains from packing into close, crystalline arrangements. your own Pins on Pinterest 3. The growing chains can add across the double bonds of rubber molecules forming polystyrene branches. The SPME fibre hosts in a Valco-tee unit sealed by a vespel ferrule. 104.4 g/mol. Questions of this type are frequently asked in competitive entrance exams like Engineering Entrance Exams and are especially useful. -[CH2-CHCl]n-, whose repeat unit is -[CH2-CHCl]-. Attend recorded … You can see it in this 3-D model on the right or in the diagram below. Polystyrene has a chain where the substituent R is a phenyl group (C6H5), corresponding to a benzene ring minus one hydrogen: -[CH2-CH(C6H5)]n-, so the repeat unit is -[CH2-CH(C6H5)]-. Thus, m = 8(AC) + 8(AH) = … Solution (a) The repeat unit molecular weight of polystyrene is called for in this portion of the problem. Compute the degree of polymerization for a polystyrene (PS) polymer with a number-average molecular weight of 260150 g/mol. C) 3.031 10 4 units. 1. Draw The Monomer, Given That This Polymer Forms By Addition Polymerization. Bonus: Use your free doubt session & get a free formula book! In many condensation polymers the repeat unit contains two structural units related to the comonomers which have been polymerized. Polymer is a combination of small … Polymers consist of many repeating monomer units in long chains, ... many monomers called styrene are polymerized into a long chain polymer called polystyrene. Polystyrene is one of the most widely used plastics, the scale of its production being several million tonnes per year. It is a rather poor barrier to oxygen and water vapour and has a relatively low melting point. As a foam, its two forms are expanded polystyrene (EPS) and extruded polystyrene (XPS). Click the 3-D picture to see an interactive version. and found to be 2.0 cal./mole°. D) 2.047 10 4 units. Join. 5 answers. All you need to do to show any repeat unit is break the double bond, show where new bonds will form if the molecule reacts with another monomer and then put a bracket around that part. The numbers preceding the poly prefix designate the first and last carbon atoms of the backbone repeating unit. (b) A simplified representation of polyvinyl acetate. We can deduce the structrure of the monomers by imagining the compounds which might be used to make the amide group. This simple structure, repeated thousands of times in a single molecule, is the key to the properties of polyethylene. Get answers by asking now. polystyrene and polypropylene are some examples of plastic in industry. This chain contains units that repeat themselves, known as repeating units. Answer to: The repeat unit in a polystyrene coffee cup has the formula C6H5CHCH2. 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