Round-Trip Copper Reactions Lab Report

AP Chemistry 12/13/11 Round-Trip Copper Reactions Lab The get of this lab was to evaluate our skills of decanting a supernatant luculent with come in losing the solid and successful completion of a series of reactions. This was done through fivesome chemical reactions involving shit. In this lab, primary(a) cop was put through five different chemical reactions in order to transmute it into different compounds. By the send away of the one-fifth reaction, the blur was back to its elemental state. In the first reaction, 0. 95 g of pure strapper was reacted with 4. 0 mL of concentrated azotic acid under the smoke hood.The solvent was swirled until all of the grunter had dissolved. The equilibrate equality for this reaction is as follows Cu (s) + 4HNO3 (aq) a Cu(NO3)2 (aq) + 2NO2 (g) + 2H2O (l) When the nitric acid came into contact with the solid bruiser, a browned foul up was immediately released into the fume hood. This brown gasoline was nitrogen dioxide as the ba lanced par supra shows. As the copper dissolved, the settlement slowly off-key blue be micturate of the copper ions. In the second reaction, distilled pissing was added to the copper (II) nitrate solution until the beaker was half full. Then, 30 mL of 3. M sodium hydroxide was added to the solution. The balanced equation for this reaction is as follows Cu(NO3)2 (aq) + 2NaOH (aq) a Cu(OH)2 (s) + 2NaNO3 (aq) When sodium hydroxide was added to the copper (II) nitrate solution, a burnished blue gel-like hasty was formed instantly. This precipitate was copper (II) hydroxide. The precipitate was blue because of the copper ions. In the one-third reaction, the copper (II) hydroxide solution was heated in a higher place a Bunsen burner. Continual stirring was necessitate to reduce the bumping, or formation of bubbles that release gas very quickly that have the potential to cause injury.The balanced equation for this reaction is as follows Cu(OH)2 (s) a CuO (s) + H2O (l) When the sol ution was heated, the bright blue precipitate slowly began to darken, at first by covering flakes of black, then eventually turning completely black. This is collect to the copper reacting with oxygen, or oxidizing. The black precipitate was allowed to drop down and then the supernatant, the clear liquid that lies above a precipitate, was decanted, or poured carefully off. Then, 200 mL of savoury distilled piss was added and the precipitate was allowed to settle to repeat the decanting movement again.In the fourth reaction, 15 mL of 6. 0 M sulfuric acid was added to the copper (II) oxide spot stirring. The balanced equation for this reaction is as follows CuO (s) + H2SO4 (aq) a CuSO4 (aq) + H2O (l) + SO2 (g) When the sulfuric acid was added to copper (II) oxide, the solution turned blue. This was due to the formation of aqueous copper (II) sulphate, which produced the copper ions to change the color of the solution. In the fifth reaction, 2. 29 g of zinc was added to the co pper (II) sulfate solution under the fume hood. The balanced equation for this reaction is written as followedZn (s) + CuSO4 (aq) a ZnSO4 (aq) + Cu (s) When the zinc was added to the copper (II) sulfate solution, the solution started to bubble. As the solution was stirred, it turned a miry blue. Small flecks of a brown solid were visible. As the solution became colorless, the brown solid settled to the place of the beaker. The solid formed was copper in its elemental state. The color faded from the solution as the copper ions slowly formed into solid copper. The copper was poured into a funnel with drop paper and washed 3 times with 25 mL of distilled water and ethanol.In order to dry the copper, it was placed on a watch glass weighing 29. 91 g over a beaker half full of water on a hot plate. One the copper appeared to be dry, the beaker was removed from the hot plate and allowed to cool. The copper was sessed on the watch glass and was save as 30. 79 g. This was left to sit o vernight and was massed again the next and recorded as 30. 77 g. By subtracting the mass of the watch glass from the final mass of the copper and watch glass, the mass of the copper was obtained and recorded as 0. 86 g. In conclusion, the percent moderate of copper from the original copper was calculate to be 90. % by the formula actual x speed of light = percent yield theoretical 0. 86 g x 100 = 90. 5% 0. 95 g In theory, the amount of copper at the end of the lab should have been the same amount that was started out with. Due to decanting and changing containers, some of the mass was lost. The calculated percent yield above is fairly straight considering that some of the mass was lost during decanting and transferring the copper from the filter paper onto the watch glass.