Exploring Metal Oxide Nature: Copper Oxide and Hydrochloric Acid
Metal oxides are compounds formed when metals react with oxygen. But do you know if they behave like acids or bases? This activity will help us understand the nature of metal oxides by observing the reaction between copper oxide and dilute hydrochloric acid.
Aim of the Activity
To observe the chemical reaction between copper oxide and dilute hydrochloric acid, and to determine the chemical nature of copper oxide.
Materials & Safety Gear
- Copper oxide (CuO) powder
- Dilute Hydrochloric Acid (HCl)
- Beaker or glass container
- Dropper
- Stirring rod (optional)
- Safety Gloves and Goggles (Mandatory)
Procedure
- Preparation: Take a small amount of copper oxide powder in a clean beaker or glass container.
- Add acid slowly: Using a dropper, slowly add dilute hydrochloric acid to the copper oxide powder.
- Stir and observe: Continuously stir the mixture while adding the acid. Keep adding the acid drop by drop until you observe a complete reaction (the solid copper oxide disappears or changes significantly).
- Note changes: Carefully observe any changes in the color of the solution and the powder, and whether any gas is evolved.
Observation
- Initially, copper oxide is a black-colored powder.
- As dilute HCl is added and stirred, the black powder gradually dissolves, and the solution turns into a distinct blue-green color.
- No gas bubbles are observed during the chemical reaction.
Explanation
The reaction between copper oxide and dilute hydrochloric acid produces copper(II) chloride (a salt) and water. The blue-green color of the resulting solution is due to the formation of copper(II) chloride.
Since a metal oxide (copper oxide) reacts with an acid (HCl) to produce a salt and water, similar to how a base reacts with an acid, this indicates that metal oxides are generally basic in nature.
CuO(s) + 2HCl(aq) → CuCl₂(aq) + H₂O(l)
Copper Oxide (solid) + Hydrochloric Acid (aqueous) → Copper(II) Chloride (aqueous) + Water (liquid)
Conclusion
This activity effectively demonstrates that metal oxides, as exemplified by copper oxide, exhibit basic properties. They react with acids in a neutralization-like reaction to form a salt and water.
Multiple Choice Questions
1. What is the color of copper oxide powder?
- a) White
- b) Black
- c) Green
- d) Blue
2. What is the nature of copper oxide?
- a) Acidic
- b) Neutral
- c) Basic
- d) Amphoteric
3. What type of chemical reaction takes place between copper oxide and hydrochloric acid?
- a) Displacement reaction
- b) Decomposition reaction
- c) Combination reaction
- d) Neutralization reaction
4. What is the color of the solution formed in this activity?
- a) Red
- b) Blue-green
- c) Yellow
- d) White
5. Name the salt formed when copper oxide reacts with HCl.
- a) Copper sulphate
- b) Copper chloride
- c) Copper carbonate
- d) Copper nitrate
Important Precaution
Always wear safety gloves and goggles when performing this experiment, as it involves handling chemicals. This activity should be conducted under the strict supervision of a qualified teacher or adult.