Copper vessels lose their shine when exposed to air due to a reaction with oxygen, moisture, and carbon dioxide in the environment. This process forms a greenish layer known as patina, which is primarily composed of copper carbonate (CuCO3​) and copper hydroxide (Cu(OH)2​).
Formation of Copper Oxide: Copper reacts with oxygen in the air to form copper(II) oxide:
- 2Cu+O2→2CuO2 This forms a dark brown or black layer on the surface.
Formation of Copper Carbonate: Copper oxide then reacts with carbon dioxide and moisture in the air to form copper carbonate, which gives a greenish color:
- CuO+CO2+H2O→CuCO3⋅Cu(OH)2 This layer, known as patina, further dulls the copper’s shine.
Other Related Questions For Practicing Before the Exam
- MCQ Test for Chemical Reactions and Equations Class 10
- Support MCQs Answer: Chemical Reactions and Equations Class 10
- Give an example of a double displacement reaction
- Name reducing agent in the given chemical reaction: 3MnO2 + 4Al → 3Mn + 2Al2O3
- Name the brown coloured gas evolved when lead nitrate crystals are heated in a dry test-tube
- Give reasons: Silver chloride is stored in dark-colored bottles.
- What changes do you observe in iron nails and the color of the copper sulphate solution if iron nails are dipped in CuSOâ‚„ solution for some time?
- Identify the chemical change: Melting of ice or conversion of milk into curd.
- Why is respiration considered an exothermic reaction?
- Why do copper vessels lose shine when exposed to air?
- Potato chips manufacturers fill the packet of chips with nitrogen gas. Why?
- Why do we store silver chloride in dark coloured bottles in labs?
- Write chemical equations of a double displacement reaction
- N₂ + 3H₂ → 2NH₃, name the type of reaction.
- What happens when milk is left open at room temperature during summer?
- What happens when quicklime is added to water?
- Define combination reaction. Give two examples of combination reactions which are exothermic in nature.
- What is decomposition reaction? Explain with the help of an example.
- Name and state the law which is kept in mind when we balance a chemical equation
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- What is rancidity? Write two ways by which it can be prevented.
- What are two conditions which promote corrosion?
- A small amount of Ferrous sulphate is heated in hard glass tube.
- What happens when Zn strip is dipped in CuSO2 solution?
- What is a redox reaction? Write down a chemical reaction representing it.
- In electrolysis of water: Name the gas collected at cathode and anode
- In the reaction: CuO(s) + H2(g) → Cu(s) + H2O (g)
- Give reasons: (a) White silver chloride turns grey in sunlight
- Compound ‘X’ decomposes to form compound ‘Y’ and COâ‚‚ gas. Compound Y is used in the manufacturing of cement.
- A metal salt MX, when exposed to light, splits up to form metal M and gas Xâ‚‚. Metal M is used to make ornaments whereas gas Xâ‚‚ is used in making bleaching powder. The salt MX is used in black & white photography.
