"Crystallization melting points" Essays and Research Papers

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    The literature value for the melting point range for Trans-9-(2-phenylethenyl)anthracene is 130-133 oC. The obtained range was lower than that at 120.3 to 123.8 oC. Because it is lower than the known value‚ this means the obtain product is not completely pure. Impurities in the compound can result in a decrease in the compounds melting point‚ which is observed here. The impurities could be 1-propanol due to an insufficient drying. If the experiment was performed again‚ the product would need to be

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    by Actual yield of synthesised aspirin: 0.347g 0.347/1.196 * 100= 29 Percentage yield: 29% Melting Points Compound Began Melting (°C) Totally Melted (°C) Range (°C) Pure Aspirin 136 1-2 Crude Aspirin 125 130 5 Product from Willow Bark 120 125 5 The documented melting point for pure aspirin is 136°C. An impure compound will exhibit a lower melting point than this‚ which is what was observed in both the willow bark product and the crude aspirin. Pure aspirin has a narrow

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    How do different liquids and solids affect the boiling and freezing point of water? Name 02/12/12 ABSTRACT There are many different substances that affect the freezing and boiling points of water. This experiment was designed to test the effects of five liquid and five solid substances/mixtures on the freezing and boiling points of water. It was hypothesized that if we tested five liquid and five solid substances/mixtures then the results would show that the solids would have a greater affect

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    Organic Compound Analysis

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    Lab 6: Organic Compound Analysis Isabella O’Toole CHY 116 Friday 1:15-4:00 Lab Conducted on 4-12-13 and 4-19-13 4-26-13 This lab was conducted in order to determine the chemical composition of an unknown organic acid. A known mass of acid was dissolved into 30mL of either water or methanol (depending on solubility) and titrated with standardized sodium hydroxide. Data from this allowed the molar

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    determining the identity of the unknown sample are listed in Table 1. Density (g/cm3) Molecular Weight (g/mol) Melting Point (ºC) Polypropylene 0.905 42.08 170 Polyethylene 0.92 28.05 130-145 Polycarbonate 1.2 158 310 Polystyrene 1.05 104 240 Polyvinyl chloride 1.4 62.5 160-172 Table 1 – Properties for five known polymers (Callister 737-775) The melting temperature of a polymer is the point at which it transforms from the solid form to a viscous liquid in which there is little molecular order (Callister

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    Plexi Glass

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    Polymer Essay: Plexiglass Many of the glass screens and windows we see today are not really made of glass. They are made of plexiglass. Plexiglass is not related to the chemical structure of glass at all. It is an organic polymer. Today this polymer is used in all sorts of applications. The formation of plexiglass was begun in 1930‚ at McGi11 University by William Chalmers‚ a research student. He polymerized methacrylic ethyl ester and methacrylic nitirile‚ creating a clear plastic paste

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    Quartz Crucible

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    virgin polycrystalline silicon which are placed in a quartz crucible along with small quantities of elements called dopants - the most common of which are boron‚ phosphorus‚ arsenic and antimony. The materials are heated to a temperature above the melting point of silicon‚ 1420 degrees Celsius. Once the polycrystalline and dopant combination has been liquefied‚ a single silicon crystal‚ the seed‚ is positioned on top of the melt‚ barely touching the surface. The seed has the same crystal orientation required

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    Physical Lab 15: Chemical and Physical Properties Experiment 1: Physical Properties of Water Data Table 1: Melting Point Data   Initial Time Final Time Observations Weigh Boat A  5:37 pm  7:00 pm 10 min- little puddle just started melting. 20 min- puddle under ice is a little bigger. 30 min- ice is melting more and getting a wetter appearance. 40 min- about half way melted. 50min- still slowly melting a bit more than half gone. 60 min- about a quarter of the cube remains. 70 min- a little les than a

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    Ap Chem

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    Christina Hang Vanessa Hang Seng Xiong Period 5 December 14‚ 2012 Molecular Mass by Freezing Point Depression Objective: Determine the molecular mass of an unknown substance by finding the change in freezing point of a solvent when the unknown substance is dissolved in it. Qualitative Data: Trials BHT (g) Cetyl –Alcohol (g) Unknown substance (g) Melting Temperature 1 0.48 g 0 0 69.3 2 0.46 g 0.09 g 0 66.9 3 0.49 g 0 0.11 g 53.7 Analysis: 1.) Determine ___ for the solution of cetyl

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    Forging Theory

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    temperature where the lowest melting constituent of steel starts to melt. The strength decreases and looses plasticity and tind to crumble under applied stress instead of flow. 2. Selection of temperature depends on a) Chemistry. b) Melting point of the lowest constituent. 3. Finishing temperatures. Lower the finishing temperature finer the structure of the piece but limited to mass and shape. The finishing temperature should be near the lower transformation point. SCALING 1. Not

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