8b-in-lab-assignment-polymer-synthesis

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Studocu is not sponsored or endorsed by any college or university 8b. In-Lab Assignment - Polymer Synthesis General Chemistry Laboratory I (University of Pennsylvania) Studocu is not sponsored or endorsed by any college or university 8b. In-Lab Assignment - Polymer Synthesis General Chemistry Laboratory I (University of Pennsylvania) Downloaded by Darinesha White (darinesha16@gmail.com) lOMoARcPSD|28564377

POLYMER SYNTHESIS In-Lab Assignment Data & Results: Part 1: Synthesis of Nylon Table 1. Volumes of Solutions Substance Measurement Volume of Solution A 10 mL Volume of Solution B 10 mL Table 2. Properties of Nylon Properties of Wet Nylon When pouring the two solutions, a film of nylon formed between the two substances. When pulling on the nylon substance, it becomes stringy and is easy to wrap around the glass rod. The resulting coil resembles that of string wrapped around a cylinder. When wet, the nylon is a milky white color and is opaque in nature. It has a very squishy feel. Properties of Dry Nylon When dry, the nylon is no longer squishy. It is firmer and stronger. It is a solid white color and is thread. It is not able to be stretched and has a weak breaking point. It is very thin and stranded. Properties of runoff from rinsing Nylon The solution contains strands of nylon that appeared to have been loosely attached to the outside of the nylon strand. Downloaded by Darinesha White (darinesha16@gmail.com) lOMoARcPSD|28564377

Part 2: Investigating Sodium Polyacrylate Table 3. Properties of Sodium Polyacrylate Mass of sodium polyacrylate 0.500 g Amount of dH20 added 135 mL Observations of Water + Sodium Polyacrylate The sodium polyacrylate is a powdery white substance prior to the addition of the water. The solution turns into an opaque white solid (cloudy) with the addition of water. When adding water, the solution expanded and turned solid. It has a gelatinous feel and smooth texture. Solution becomes softer as more water is added. Capacity of sodium polyacrylate (ml H 2 0/g) 135/0.5 = 270ml/g Mass of NaCl Added 0.123g Observations after adding NaCl After adding NaCl, the substance goes from solid to a viscous liquid solution. The solution is an opaque white color with a cloudy appearance. The solution comprises of small specs/clumps of solidified substance. Part 3: Investigating Cross-Linking Table 4. Cross-Linking Properties Mass of Solid PVA 0.510 g mL of DI water 15 mL Temperature at which water is heated 100 °C Downloaded by Darinesha White (darinesha16@gmail.com) lOMoARcPSD|28564377

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Observations/Properties of polyvinyl alcohol solution While heating and stirring on the hot plate, the solution was bubbling a bit and was clear and colorless. After the 10 minute heating period, bubbles still remain on the surface of the solution. mL of 4% sodium borate solution 5 mL Table 5. Effect of addition of Borate to solution Time (s) Total Drops of borate Observations of stirbar Observations of Solution 0 0 The stirbar moves easily and without anything impeding its motion The solution is clear and colorless with some bubbles on the top 30 5 The stirbar is moving slightly slower The solution remains clear with bubbles on the surface 60 10 Stir bar is moving slightly slower Solution appears the same, clear and colorless 90 15 Stir bar is not able to make full rotations in solution anymore Solution is clear, however, it becomes much more viscous and is gooey in nature. 120 20 Stir bar is not stuck Solution is clear Downloaded by Darinesha White (darinesha16@gmail.com) lOMoARcPSD|28564377

in solution, and is unable to make half turns and gooey and solid. Bubbles are trapped within entire solution. Observations after producing slime:  Slime is very sticky and gooey. It is also relatively see-through, not completely clear. It is colorless  When pulled on fast, the slime breaks easily into chunks  When pulled on slowly, the slime stretches with the pull  The polymer is slightly bouncy when dropper onto the counter  It takes about 6-9 seconds to stretch the polymer 3 inches. Questions: 1. In lecture, we watched a video that discussed an application of super absorbent polymers. Identify and give a brief description of this application. a. The application of the super absorbent polymers that the video discusses refers to using the polymer as a coating on military vehicles. When shot at using an AK47, a tank without the polymer coating leaks water (or gas) at a high rate; however, a tank with the polymer immediately seals the bullet hole, preventing excess liquid from spilling out of the tank. This process is so fast, that the high speed camera had trouble capturing the sealing of the polymer after the tank was punctured by the bullet. 2. We did not calculate the percent yield for our nylon synthesis because we did not have time to fully dry the product, but it is an important aspect of synthesis. Another difficulty is that the polymer chain length can be variable, so the molecular weight of the monomer is used. a. Assume you begin with exactly 20.00 mL of each reactant. What is the limiting reagent? Show your work. (0.02L)(0.5M hexamethylendiamine) = 0.01 mol hexamethylendiamine (0.02L)(0.2M sebacoyl chloride) = 0.004 mol sebacoyl chloride sebacoyl chloride is the limiting reagent b. What is the theoretical yield in grams of Nylon 6-10? Downloaded by Darinesha White (darinesha16@gmail.com) lOMoARcPSD|28564377

1:1 ratio of sebacoyl chloride to nylon 6-10 0.004 mol sebacoyl chloride = 0.004 mol nylon 6-10 (0.004 mol nylon 6-10)(282.42 g/mol nylon 6-10) = 1.13 g nylon 6-10 3. In lab, you added a certain amount of water to sodium polyacrylate and made observations. Then, you added salt to the mixture. a. What happened when you added sodium chloride to the water-sodium polyacrylate mixture? i. When we added the sodium chloride to the water-sodium polyacrylate mixture, the solution turned form a viscous solid to a less viscous liquid solution. b. Explain why (chemically) the salt had an effect on the mixture. i. Chemically, when adding NaCl, there is an imbalance between the sodium within the solid solution and the sodium outside in the sodium chloride that is added to the solution. Therefore, through osmosis, the water exits the polymer to balance the concentrations of sodium within and outside of the polymer turing the solution into liquid. 4. The last part of your polymer experiment involved investigating the effect of crosslinking on a polymer’s viscosity. a. What does it mean when a polymer is crosslinked? i. A cross linked polymer is when bonds are formed between polymer chains. This is a covalent linkage between two polymers, or two different regions of the same polymer. b. How did the viscosity of a highly crosslinked-polymer compare to that of one with less crosslinking? i. The more borate we added, the more solidified the solution became. Adding borate increased the cross-linking which increased viscosity. Therefore, a highly crosslinked polymer is more viscous than one with less cross-linking. 5. Which of the following substances exhibits H bonding? If not, explain why. For those that do, draw two molecules of the substance with the H bonds between them. a. C 2 H 6 i. This molecule does not exhibit H bonding. In order for H bonding to exist between two identical molecules, H has to bond to a electronegative molecule. Carbon is not an electronegative molecule like that of N, O, or F and therefore is unable to exhibit hydrogen bonding. b. CH 3 OH Downloaded by Darinesha White (darinesha16@gmail.com) lOMoARcPSD|28564377

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