Data and Observations
Remember to use the correct number of significant figures and show your work for calculations.
Mass of copper wire _0.25_ g
Mass of empty beaker __67.23_ g
Mass of beaker and dry copper __67.46 g
Mass of recovered copper ____0.23_ g
Percent copper recovered ___92.0_ %
Observations
- There was an observation of a colorless gas after a piece of copper wire (0.25g) dissolves in 10mL of Nitric Acid. The color is transformed from colorless to blue/green. However, the color fades when it is diluted in water.
- The formation of Sodium nitrate and Copper Hydroxide occurs. The color transforms from pale blue to a Dark blue color.
- When heating of the solution occurs with constant stirring, the color changes to dark green, and a there is a noticeable formation of a solid precipitate beneath the beaker.
- When 15mL of 6M Sulphuric Acid is added to the precipitate, the dark green solid changes to a light blue solution. There is no release of gas. This indicates the formation of Copper Sulphate.
- After the addition of 1.0g of zinc powder, there is the release of gas and bubbles are observed. The solution changes from light blue color to a milky blue precipitate with the formation of black solid deposits.
- Eventually, a solid brown color results after the solid is washed in deionized water.
Analysis of Data
The main plan of the experiment was to clarify John Daltons Theory, which states that mass cannot be created or destroyed. This is proved using Copper which was subjected through diverse reactions, in a process referred as the Cycle of Copper Reactions. The mass of copper wire was inserted in a beaker and the combined mass measured. Then the mass of the beaker was measured without the contents to obtain the mass of the wire.
The prior reaction was dissolving copper in Nitric Acid in a fume chamber.
8 HNO3 (aq) + 3 Cu (s) + O2 (g) → 3 Cu(NO3)2 (aq) + 4 H2O (l) + 2 NO2 (g)
There was the formation of a light blue colour indicating the presence of Cu(NO3)2.
In the second reaction, Aqueous Sodium Hydroxide was added to the solution obtained above.
Cu(NO3)2 (aq) + 2 NaOH (aq) → Cu(OH)2 (s) + 2 NaNO3 (aq)
Eventually, the solution turned dark blue. No gas was produced. After heating the solution turned from deep blue to green with the formation of solid particles . the final product was a grey solution with a black precipitate.
Cu(OH)2 (s) → CuO (s) + H2O (l)
The next step was the addition of Sulphuric acid,
CuO (s) + H2SO4 (aq) → CuSO4 (aq) + H2O (l)
There was the change of colour after the addition of Sulphuric acid, and the grey solution changed to light blue solution. This was Copper Sulphate. The final step was the addition of Zinc powder on the light blue solution , resulting to the formation of a milky blue precipitate and black precipitate at the bottom of the beaker.
CuSO4 (aq) + Zn (s) → ZnSO4 (aq) + Cu (s)
Discussion
The experiment developed using a mass of copper wire, this was better because the rate of reaction of copper powder has a faster rate. The experiment was cautious as copper has the capability of exploding causing the splash of dangerous materials.
