An exothermic reaction started immediately with concomitant orientation of a brown precipitate of crude actinide. Ml of water and a magnetic stirring bar were added to stir the reaction mixture and the flask was heated on a magnetic stirring hot plate until all of the solid and oil were dissolved. The temperature of the reaction mixture at this point was close to ICC, the boiling point of water. A few millimeters of hot solution was removed from the flask with a disposable pipette and placed in a test tube.
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The test tube was set aside to cool and produce crystals. The color and melting point of the in batch of crystals were used to assess the effectiveness of activated carbon treatment of the main batch to remove the colored impurities (vide infra). The temperature of the main batch of the reaction mixture in the Erlenmeyer flask was brought down to 70-ICC, and approximately a pinch of activated carbon were added to the solution. The reaction mixture was carefully brought to boiling with efficient stirring, to prevent bumping over of the reaction mixture.
The hot solution was filtered through a double layer of fluted filter paper arranged in a conical glass funnel, previous heated over a boiling water bath. To complete crystallization, the filtrate was cooled in an ice bath. The crystals were collected by suction filtration. The collected product was spread over a filter paper to dry until the next class period. Dried actinide showed melting point, 112-ICC, yield 2. Grams. The crystals from the mini batch that was not treated with charcoal were collected by suction filtration using a Hirsch funnel.
These crystals had brown color and showed melting range of 106-ICC, yield 0. Egg. Percent Yield Calculations: Weight of aniline = 2. 0 g Molecular weight of aniline= 93 Molecular weight of actinide = 135 Theoretical Yield Actual Yield = 2. 03 g + 0. 01 g = 2. 04 g % Yield 100 – – 70. 3% Yield Results and Discussion: In this experiment, aniline (liquid) was reacted with acetic anhydride (liquid) in water at room temperature to give an impure, tan colored solid. The solid was crystallized from water with the use of charcoal to give white flakes of actinide, melting point 112-ICC, actual yield 2. 4 grams. When charcoal was not used urine crystallization, the crystals remained an off-white color. The melting point of the mini batch of brown/tan crystals was 106-ICC. The overall reaction between aniline l, and acetic anhydride, II leading to the formation of actinide is shown below in the first equation. The mechanism of the reaction between the two reactants to produce the actinide is shown in the second equation. In equation 2, the curved arrows represent the flow of electrons during bond formation and bond cleavage. Observations: a.
Reactants aniline and acetic anhydride were both insoluble in water, the action medium; however, when the reaction was swirled by hand, an exothermic reaction took place within minutes which produced the solid actinide. B. Acetic anhydride is a high energy molecule. C. Both aniline and water can react with acetic anhydride, but aniline reacts with acetic anhydride at a much faster rate to produce actinide. D. Charcoal was very effective in removing colored impurities from the impure batch of actinide. Questions: 1. The major purpose of crystallization is to purify a solid. . Water is nonflammable and nontoxic. . Used to remove small amounts of colored impurities. Activated carbon absorbs the polar compounds. 4. Because if we add more solvent, then we can vaporize it off. 5. Because because many organic compounds are not soluble in water because it is hydrophobic. These compounds are soluble in ethanol because of ethanol’s functional groups. The chemist can then add more water to the solution because the organic compound is soluble in the ethanol. 6. We do not use Benzene and water because they do not dissolve with each other. Like dissolves like.