Homework 5-solutions - jaw2435 – Homework 5 – Walker...

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Unformatted text preview: jaw2435 – Homework 5 – Walker – (53985) 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0 points Of the Big Six polymers, which contains the highest percentage of carbon by mass? 1. polypropylene 2. polyethylene glycol 3. PVC 4. polystyrene correct Explanation: 002 10.0 points Calculate the molar mass of a polystyrene molecule composed of 5000 monomer units. 1. 5 . 2 × 10 5 g correct 2. 1 . 56 × 10 6 g 3. 1 . 04 × 10 6 g 4. 2 . 6 × 10 4 g Explanation: 003 10.0 points How can polystyrene be either hard and trans- parent like a CD case or soft and opaque like a Styrofoam cup? 1. The former is made at high density and the latter by incorporating air (or solvent) into the process to make a honeycomb like structure. correct 2. The former is made with the benzene rings all on the same side of the polymer chain and the latter with an alternating arrangement. 3. The former is made highly branched and the latter by a great deal of cross-linking. 4. The former is made at low density and the latter at high density. 5. The former is made using low molecular weight polystyrene and the latter with high molecular weight polystyrene. Explanation: 004 10.0 points On heating, a thermoplastic 1. softens. correct 2. becomes insoluble. 3. increases its resistance to wear. 4. breaks up. 5. hardens. Explanation: 005 10.0 points Polyesters belong to which class of polymers? 1. silicones 2. acid 3. condensation correct 4. rearrangement 5. addition Explanation: 006 10.0 points Which of the following is NOT a problem or potential problem with plastics? 1. Most of the synthetic plastics are non- biodegradable. 2. A large number of covalent bonds present in these materials may cause a violent reaction when exposed to ultraviolet light. correct 3. When these materials are burned a toxic gas is produced....
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This note was uploaded on 05/01/2008 for the course CH 305 taught by Professor Sutcliffe during the Spring '08 term at University of Texas at Austin.

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Homework 5-solutions - jaw2435 – Homework 5 – Walker...

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