How Does Cupric Oxide Benefit Chemistry Students?
Cupric oxide is an inorganic chemical compound composed of cuprous ion and oxide ion. Cupric cuprous are the two forms of copper ions. Copper exists in two types of oxide, the one is with a higher oxidation state and another one is with a lower oxidation state, cupric oxide and cuprous oxide respectively.
Cupric Oxide and Cuprous Oxide
The oxides of copper are of two types:
Cupric oxide- It is also known as copper cupric oxide. The oxidation state of copper in this compound is +2. +2 is the highest oxidation state of copper. Generally, in short, you can write it as oxide cupric. It exists in the monoclinic crystal system.
Cuprous oxide- the oxidation state of copper in this compound is +1. +1 is the intermediate oxidation state of copper. It can easily get oxidised or reduced.
The oxides of cupric cuprous are represented as CuO and Cu2O respectively.
Preparation of Cupric Oxide and Cuprous Oxide
Cupric Oxide can be prepared by the following methods:
It can be produced by the thermal decomposition of the cupric carbonate.
CuCO3 → CuO + CO2
The thermal decomposition of cupric carbonate forms cupric oxide as a product and carbon dioxide gas as a byproduct.
Another method of Cupric oxide preparation is heating copper in the presence of air at a high temperature (around 300-800 degrees celsius).
Cu + O2 → CuO
Heating Copper Nitrate- The nitrate of copper is thermally unstable. On heating copper nitrate at a temperature around 180 degrees celsius.
2Cu (NO3)2 → 2 CuO + O2 + 4 NO2 (this reaction takes place at a temperature around 180 degrees celsius)
Heating Cupric Hydroxide- cupric hydroxide is a thermally unstable compound. It gets easily decomposed into cupric oxide on heating.
Cu(OH)2 → CuO + H2O
Properties of Cupric Oxide
Physical Properties of Cupric Oxide
Cupric oxide is a black colour compound.
Cupric oxide exists in powder (amorphous) form.
The melting point of cupric oxide is 1326 degrees celsius.
Cupric oxide is insoluble in water.
Cupric oxide is soluble in ammonium chloride and potassium cyanide.
Chemical Properties of Cupric Oxide
Cupric acid reacts with strong mineral acids like hydrochloric acid (HCl), sulphuric acid (H2SO4), and nitric acid (HNO3) to form salts.
CuO + HNO3 → Cu (NO3)2 + H2O
CuO + 2HCl → CuCl2 + H2O
CuO + H2SO4 → CuSO4 + H2O
Cupric oxide reacts with the concentrated base and forms salt.
2KOH + CuO + H2O → K2 [Cu (OH)4]
Cupric oxide reacts with hydrogen and gets reduced to copper.
CuO + H2 → Cu + H2O
Cupric oxide reacts with carbon monoxide and forms elemental copper and carbon dioxide.
CuO + CO → Cu + CO2
Cupric oxide reacts with carbon and forms the elemental form of copper.
2CuO + C → 2Cu + CO2
Uses of Cupric Oxide
Cupric oxide is used as a pigmenting agent in ceramic compounds. It gives blue, red, green, grey, pink, and black glazes.
Cupric oxide is widely used in laboratories for the preparation of various copper salts.
Cupric oxide is used in the manufacture of wood preservatives.
Cupric oxide is used in the welding process.
Cupric oxide is used in the manufacture of lithium batteries.
Did You Know?
Paramelaconite is a copper mineral. In this mineral, copper exists in both +1 and +2 oxidation state.
Do you think that copper was the first element used by man along with gold and iron?
Copper is an essential element for the human body.
Copper is used in alloy formation.
The blood of octopus contains copper as an oxygen carrier. Therefore, the colour of the blood in them is blue.
Copper is an essential trace mineral.
Copper is used as a supplement with iron for the anaemic person.
FAQs on Cupric Oxide: Preparation, Properties, and Key Uses
1. What is cupric oxide, and what is its chemical formula?
Cupric oxide, also known as Copper(II) oxide, is an inorganic compound representing the higher oxide of copper. It is a black solid with the chemical formula CuO. In this compound, copper exists in its +2 oxidation state.
2. What are the key physical properties of cupric oxide (CuO)?
The main physical properties of cupric oxide are:
- Colour and Form: It is a fine, black powder in its amorphous form.
- Solubility: It is practically insoluble in water and alcohol but dissolves in dilute acids, ammonium chloride, and potassium cyanide solutions.
- Melting Point: It has a high melting point of 1326°C (2419°F).
- Structure: It has a monoclinic crystal structure.
3. How is cupric oxide commonly prepared?
Cupric oxide can be prepared through several methods, including:
- Heating copper in air: Roasting copper metal in the presence of oxygen above 300°C.
2Cu + O₂ → 2CuO - Thermal decomposition: Heating copper compounds like copper(II) nitrate, copper(II) hydroxide, or copper(II) carbonate.
2Cu(NO₃)₂ → 2CuO + 4NO₂ + O₂
Cu(OH)₂ → CuO + H₂O
4. Why is CuO specifically called 'cupric' oxide and not 'cuprous' oxide?
The name 'cupric' is used to denote the higher oxidation state of the copper ion. In CuO, copper has an oxidation state of +2 (Cu²⁺). The suffix '-ic' signifies this higher state. In contrast, 'cuprous' oxide refers to copper in its +1 oxidation state (Cu⁺), which has the formula Cu₂O. Therefore, the name directly indicates the chemical nature of the copper ion in the compound.
5. What is the fundamental difference between cupric oxide (CuO) and cuprous oxide (Cu₂O)?
The primary difference lies in the oxidation state of copper, which leads to different properties:
- Oxidation State: In cupric oxide (CuO), copper is in the +2 state. In cuprous oxide (Cu₂O), copper is in the +1 state.
- Colour: CuO is a black solid, whereas Cu₂O is a reddish-brown solid.
- Chemical Formula: The formulas are CuO and Cu₂O, respectively, reflecting the different ratios of copper to oxygen.
- Stability: CuO is more stable at moderate temperatures, while Cu₂O is formed at higher temperatures.
6. Is cupric oxide an acidic or a basic oxide? Explain why.
Cupric oxide (CuO) is a basic oxide. This is because it is an oxide of a metal that reacts with acids to form a salt and water, which is a characteristic property of bases. For example, it reacts with hydrochloric acid to form copper(II) chloride (a salt) and water.
Reaction: CuO(s) + 2HCl(aq) → CuCl₂(aq) + H₂O(l)
7. What are the important applications of cupric oxide in various industries?
Cupric oxide has several important industrial uses, such as:
- Pigment: It is used as a pigment in ceramics, glazes, and enamels to produce blue, green, or red colours.
- Catalyst: It serves as a catalyst in various organic synthesis reactions.
- Polishing Agent: It is used as a polishing agent for optical equipment.
- Batteries: It is used as a component in dry cell batteries and lithium-ion batteries.
- Agriculture: It is used in animal feed as a source of copper and sometimes as a fungicide.
8. How does cupric oxide demonstrate its role as an oxidizing agent?
Cupric oxide acts as an oxidizing agent because it can donate its oxygen atom to another substance, causing that substance to be oxidized while CuO itself gets reduced to copper metal. A classic laboratory example is the reaction with hydrogen gas, where cupric oxide oxidizes hydrogen to water.
Reaction: CuO + H₂ → Cu + H₂O
