Preparation of Pure Diphenyl

1794 WordsNov 3, 20128 Pages
Experiment 2 Date: 24 January 2006 Title : Crystallization of a Crude Sample Objective : Preparation of pure diphenyl via crystallization of crude diphenyl dissolved in ethanol. Structural Formula of Organic Substances Involved : Diphenyl Ethanol Apparatus : Round-bottom flask (100 mL), measuring cylinder (50 mL), conical flask (50 mL), filter flask, beaker (100 mL), stemless glass funnel, Hirsch funnel, capillary tube, long glass tube, watch glass, glass vial, water condenser, retort stand, retort clamps, spatula, cork stand, fluted filter paper, filter paper for Hirsch funnel, electronic weigh, electrothermal heater, oven, aspirator, electrothermal device to determine melting point. Chemicals : Crude diphenyl (3.0 g),…show more content…
The capillary tube is then inserted into electrothermal device that is being used to determine the melting point and observed from the magnifying lens of the device. The device is then switched on to heat the crystals. As the crystals are being heated, the temperature reading of the device is being observed. The temperature when the crystals are noticed to start to melt is being recorded as Ti and the temperature when the crystals have completely transformed into liquid form is recorded as Tf. Ti – Tf marks the range of the melting point of the diphenyl crystals. Upon completion of the experiment, it was calculated that the percentage yield of the crystalline product is approximately 60 %, as shown in the calculations below: Percentage yield = = = 63.88% Such value of the percentage yield can be attributed to several factors. Among these include the possibility of the vaporization of the ethanol solvent into the air during the reflux heating process and thus causing the crude diphenyl to not dissolve entirely. Other than that, during gravity filtration, a small amount of diphenyl may be left on the fluted filter paper and inside the beaker in liquid form. The same also applies during vacuum filtration, whereby tiny bits of diphenyl crystals are still found sticking on the Hirsch funnel filter paper and also on the internal walls on the funnel, which proves to be
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