Pre-Lab Questions
- Balanced equation
- Cu + 4 HNO3 = Cu (NO3)2 + 2 NO2 + 2 H2O
- Cu (NO3)2 + 2 NaOH = Cu (OH)2 + 2 NaNO3
- Cu (OH)2 = Cu O + H2O
- Cu O + H2SO4 = CuSO4 + H2O
- CuSO4 + Zn = Cu + ZnSO4
- Type of reaction
| A | (Redox reaction) |
| B | (Double replacement) |
| C | (Decomposition) |
| D | (Double replacement) |
| E | (Single replacement) |
- There are two categories of Litmus Paper: Red Litmus Paper and Blue Litmus Paper. Acidic material turns the blue litmus paper into red. Whereas, if the material is alkaline or basic then the red litmus paper turns blue in nature.
- Nitric acid (concentrated) is highly corrosive and oxidizing in nature and hence, it is essential to wear protective goggles or say use face shield. Must use fume hood and also do check glass apparatus twice before using. Also, the produces nitrogen dioxide gas is highly toxic which means it is imperative to completely dissolve it in water or else use glass wool in the neck of flask to control any possible diffusion of remaining nitrogen oxide.
Observations
| Reaction | Observations |
| Reaction A: Copper + nitric acid | Copper metal gets dissolved in the nitric acid which mean nitrate ion oxidized the cu metal into copper (II) ion and acid turns into toxic NO2 gas in brown color |
| Reaction B: Copper (II) nitrate + sodium hydroxide | Dilute copper nitrate is then mixed with NaOH which produces Cu (OH)2 of blue/green color in exchange reaction |
| Reaction C: Copper (II) hydroxide, water | Further, Copper (II) hydroxide water mixture is tested with pH paper and it turns blue due to excess NaOH which shows it is basic in nature |
| Reaction D: Copper (II) oxide +sulfuric acid | The black colored CuO will turn blue CuSO4 and gets dissolved in the water solution. |
| Reaction E: Copper (II) sulfate + zinc | The metal zin will replace the Cu from CuSO4 and elemental copper (Red or copper colored) will produce. |
Analysis and Interpretation
- A. Copper is less active as compared with zinc. Also, zinc has higher tendency of being oxidized as compared with copper. Therefore, Zin reacts with sulfuric acid but not with the copper.
B. Magnesium can be used in place of zinc. However, sodium cannot be used because sodium catches fire in aqueous medium and reacts violently. Hennce, Na cannot be used.
C. The reaction rate is directly proportional to the surface area of the reactants. Here, if lump of zinc is used then it slower the reaction rate and therefore, in order to increase the surface area of the reactant powered zinc is used.
- Considering that all molecules reacted completely then the mass of copper that should be recovered at the end of the reaction would be equal to the initial mass of the copper which is 0.10 grams.
- Reaction A: Cu + 4 HNO3 = Cu (NO3)2 + 2 NO2 + 2 H2O is not double displacement reaction because in this reaction copper gets oxidized and the nitrogen is reduced which means this is redox reaction and not double displacement.
- The best suitable procedure to recover the copper (II) oxide is to just heating the solution till the complete black solid observed rather than treating it with the sulfuric acid. Further, filter paper can be used to filter out the black solid copper in the form of precipitate.
- In reaction E: CuSO4 + Zn = Cu + ZnSO4, zin replaces Cu2+ ions and hence, the liquid portion has both these ions Cu2+ and Zn2+.
