AP Chemistry 12/13/11 Round-Trip Copper Reactions Lab The aim of this lab was to guage our expertise of decanting a supernatant liquid with out dropping the stable and profitable completion of a collection of reactions. This was accomplished via 5 chemical reactions involving copper. On this lab, elemental copper was put via 5 totally different chemical reactions with a view to convert it into totally different compounds. By the top of the fifth response, the copper was again to its elemental state. Within the first response, zero. 95 g of pure copper was reacted with four. zero mL of concentrated nitric acid underneath the fume hood.
The answer was swirled till the entire copper had dissolved. The balanced equation for this response is as follows: Cu (s) + 4HNO3 (aq) a Cu(NO3)2 (aq) + 2NO2 (g) + 2H2O (l) When the nitric acid got here into contact with the stable copper, a brown gasoline was instantly launched into the fume hood. This brown gasoline was nitrogen dioxide because the balanced equation above exhibits. Because the copper dissolved, the answer slowly turned blue due to the copper ions. Within the second response, distilled water was added to the copper (II) nitrate resolution till the beaker was half full. Then, 30 mL of three. M sodium hydroxide was added to the answer. The balanced equation for this response 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 resolution, a shiny blue gel-like precipitate was fashioned immediately. This precipitate was copper (II) hydroxide. The precipitate was blue due to the copper ions. Within the third response, the copper (II) hydroxide resolution was heated above a Bunsen burner. Continuous stirring was required to cut back the “bumping”, or formation of bubbles that launch gasoline in a short time which have the potential to trigger harm.
The balanced equation for this response is as follows: Cu(OH)2 (s) a CuO (s) + H2O (l) When the answer was heated, the intense blue precipitate slowly started to darken, at first by displaying flakes of black, then finally turning utterly black. That is because of the copper reacting with oxygen, or oxidizing. The black precipitate was allowed to settle after which the supernatant, the clear liquid that lies above a precipitate, was decanted, or poured fastidiously off. Then, 200 mL of scorching distilled water was added and the precipitate was allowed to settle to repeat the decanting course of once more.
Within the fourth response, 15 mL of 6. zero M sulfuric acid was added to the copper (II) oxide whereas stirring. The balanced equation for this response 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 answer turned blue. This was because of the formation of aqueous copper (II) sulfate, which produced the copper ions to vary the colour of the answer. Within the fifth response, 2. 29 g of zinc was added to the copper (II) sulfate resolution underneath the fume hood. The balanced equation for this response is written as adopted:
Zn (s) + CuSO4 (aq) a ZnSO4 (aq) + Cu (s) When the zinc was added to the copper (II) sulfate resolution, the answer began to bubble. As the answer was stirred, it turned a cloudy blue. Small flecks of a brown stable had been seen. As the answer turned colorless, the brown stable settled to the underside of the beaker. The stable fashioned was copper in its elemental state. The colour pale from the answer because the copper ions slowly fashioned into stable copper. The copper was poured right into a funnel with filter paper and washed thrice with 25 mL of distilled water and ethanol.
With the intention to dry the copper, it was positioned on a watch glass weighing 29. 91 g over a beaker half stuffed with water on a scorching plate. One the copper seemed to be dry, the beaker was faraway from the new plate and allowed to chill. The copper was massed on the watch glass and was recorded as 30. 79 g. This was left to take a seat in a single day and was massed once more the following and recorded as 30. 77 g. By subtracting the mass of the watch glass from the ultimate mass of the copper and watch glass, the mass of the copper was obtained and recorded as zero. 86 g. In conclusion, the % yield of copper from the unique copper was calculated to be 90. % by the system: precise x 100 = % yield theoretical zero. 86 g x 100 = 90. 5% zero. 95 g In principle, the quantity of copper on the finish of the lab ought to have been the identical quantity that was began out with. Resulting from decanting and altering containers, a few of the mass was misplaced. The calculated % yield above is pretty correct contemplating that a few of the mass was misplaced throughout decanting and transferring the copper from the filter paper onto the watch glass.
