Molecular Basis for Material PropertiesCatherine Lozier03/05/2013Chem 1310 Section C02TA Ryan BucherLab Partners:Chelsey Arnold Sunya MorinTran GHonor Pledge: I did not copy this work from any others student(s), current students in lab or old lab reports ________________________________________________SignatureDATA AND OBSERVATIONSPart APolymerSampleFluid Initial Final ElapsedTime (min)Dimensions(mm) LxWxHMass (g) Dimensions(mm) LxWxHMass (g)Gummy bear Water 19.6 x 9.0 x 11.0 2.512 24.1 x 10.4 x 13.5 3.838 100Gummy bearSalt water 19.6 x 10.2 x 10.4 2.583 22.5 x 12.0 x 11.1 3.307 100Gummy bearAlcohol 20.0 x 10.1 x 10.7 2.546 20.0 x 9.7 x 11.1 2.559 100Polymer beadWater 2.8 diameter 0.019 10.5 diameter 0.722 100Polymer beadSalt water 3.2 diameter 0.029 6.4 diameter 0.145 100Polymer beadAlcohol 2.7 diameter 0.023 3.2 diameter 0.027 100PolymerSampleFluid Increase Polymer DensityVolume (mL) Mass (g) Initial FinalGummy bear Water 14.432 1.326 0.129 0.113Gummy bear Salt water 9.178 0.724 0.124 0.110Gummy bear Alcohol -0.08 0.013 0.118 0.119Polymer bead Water 0.804 0.703 0.309 0.834Polymer bead Salt water 0.241 0.116 0.361 0.451Polymer bead alcohol 0.023 0.004 0.402 0.336Part BPolymer Sample Volume(mL)Mass (g) Density(g/mL)Elasticity Response toHeat ColdGlue & borax 10 9.709 0.971 28% Melted, slight odor,does not transfer heatquicklyNo changePVA & borax 45 35.881 0.797 6% Spread out, meltedquicklyNo changeSodium silicate & ethanol9 12.478 1.386 63% Melted, bubbled No changeLatex & acetic acid6 5.580 0.930 53% Odor, sweats clearliquidNo changeObservations of Polymer CharacteristicsPVA mixtures became more fluid as % borate decreased. 2% and 1% mixtures did not form ball, stuck to container walls, hands. 4% mixture stuck to hands if handled too roughly. Transparent, with suspended bubbles, likely due to air that was trapped during the mixing process.Latex quickly formed ball, developed in layersGlue & borax did not transfer heat at all; could touch surface after several minutes of heatingPart CElement Atomic Radius (pm) Estimated Ga-X Bond LengthGallium 141 NAArsenic 139 280Phosphorus 128 269Nitrogen 65 206LED Wavelength(s) at PeakMaximum (nm)Voltage Measured SemiconductorCompositionBlue 431.7 3.49 InxGa1-xNGreen 570.8 2.22 GaP1.00As0.00Yellow 591.1 1.91 GaP0.85As0.15Orange 617.3 1.79 GaP0.65As0.35Red 651.7 1.72 GaP0.40As0.601.7 1.8 1.9 2 2.1 2.2 2.3520540560580600620640660f(x) = − 142.91x + 880.69R² = 0.82Wavelength (nm) v. Voltage (V)Voltage (V)Wavelength (nm)30 40 50 60 70 80 90 100 110520540560580600620640660f(x) = − 1.35x + 705.26R² = 1Wavelength (nm) v. Phosphorous Composition (%)Phosphorus Composition (%)Wavelength (nm)DISCUSSIONPart AThe objective of Part A was to observe the reactions of polymers in various liquids. For both the polymer beads and the gummy bears, soaking in water led to the highest change in volume and mass. However, the density ofthe gummy bear decreased from 0.129 g/mL to 0.113 g/mL, whereas the density of the polymer bead more than doubled from 0.309 g/mL to 0.834 g/mL. Soaking in salt water also caused the gummy bear density to decrease from0.124 g/mL to 0.110 g/mL, and caused the polymer bead density to increase from 0.361 g/mL to 0.451 g/mL. For alcohol, the results were reversed, and the gummy bear’s density increased by 0.001 g/mL while the polymer bead’s density decreased by 0.066 g/mL. For water and salt water, the differences between initial and final states are very pronounced and it is unlikely that error had much influence on the relative measurements. However, the changes associated with alcohol were so small that they could be attributed to human error in measurement. A caliper was used to take the dimensions of the samples, and any pressure could have slightly compressed the samples. This is especially true of the gummy bears, which were very elastic and could have been deformed while taking volume measurements. Both polymers absorbed large quantities of water due to the polar groups in their structures. These groups attract the polar water molecules, which engage in hydrogen bonding and cause the polymer to swell. The polymers did not have a significant reaction to alcohol because alcohol is nonpolar and did not have any hydrogen bonding with the polymers.Part BThe objective of Part B was to synthesize various polymers and observe their physical properties. The sodium silicate and ethanol polymer has the highest density (1.386 g/mL) and elasticity (63%). Latex and acetic acid had a similar elasticity rating of 53%, but had a lower density (0.930 g/mL). PVA and borax had the lowest density (0.797 g/mL) and the lowest elasticity (6%). The glue and borax, PVA and borax, and sodium silicate and ethanol polymers melted, but the latex and acetic acid polymer remained solid after several minutes of exposure to 200ºC conditions. The mass measurements for the PVA and borax polymer are inaccurate due to human error. When transferring the polymer from the mixing cup to the weigh paper, several mL stuck to the container and gloves. Therefore the measured mass of the polymer is artificially low. Elasticity measurements were also subject to human error, as the bounce height was eyeballed against a meter stick. Observations for each trial varied, and the rough average was recorded. Also, the polymer rarely bounced straight up, and some energy might have been translated into horizontal movement.Part CThe objective in Part C was to demonstrate the relationship between voltage, phosphorus content, and wavelength in LEDs. The relationship between voltage and wavelength, which should have been roughly linear, had an R2 value of 0.8169 when fitted with a linear regression line. The voltages measured for yellow and orange, which should have been 2.10 < V < 2.18 and 2.03 < V < 2.10 respectively, were 1.91 V and 1.79 V, which are much lower than expected. The relationship between wavelength and phosphorus was linear, with an R2 value of 0.9999 for a linear regression. The discrepancies between the expected and measured voltages could be due to faulty equipment or human error in probe placement.DISCUSSION QUESTIONS1. Because the cross-linker between the PVA monomers is the salt sodium borate, it is likely that the PVA and borax polymer is not covalently bonded. The sodium borate dissolves in the PVA, and the interactions between the borate ions and the polar oxygen atoms in the PVA chain creates a gel polymer.2. It is not theoretically possible to create a