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Copper Oxide, also better known as Cuprous(I) Oxide, lacks carbon and hydrogen bonds and comes under the category of inorganic compounds. The compound also exhibits covalent properties. The constituent element copper is known to be a good electrical conductor. Despite this Cu2O (Cuprous Oxide) is an insulator. Copper oxide is also photosensitive. When crystallized, it does so in a cubic structure. The article below will focus on various aspects of Copper Oxide and will discuss some important questions.
| Table of Contents |
Key Terms: Copper Oxide, Cupric Oxide, Chemical Properties, Physical Properties, Oxidation, Reduction
What is Copper Oxide?
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Copper oxide is another metallic oxide compound that is slightly conducting in nature. This compound is also known as a semiconducting compound. Copper oxide has a monoclinic structure. The compound is more known than others because it also holds the position of being the simplest of all members in the family of Cu (Copper). Copper Oxide also has a wide range of physical properties. These are of help in many instances.
Copper oxide
These physical properties consist of spin dynamics, superconductivity in high temperatures, showing electron correlation effect, etc. Copper oxide can be easily mixed with liquids having polarized nature. This oxide of copper is also very stable in both its physical and chemical properties. Cu2O mostly exists as a red powder. It also plays a valuable role in acting as an antimicrobial agent. Copper Oxide can very easily be reduced with the help of Hydrogen. The reduction is facilitated by the use of electricity or heat. Reduction into copper metal makes it a conductor of electricity again. Cuprous Oxide undergoes a disproportionation reaction when in acid solutions. This results in the formation of Cupric Oxide and Copper.
Other Important Specifications:-
| Property | Value |
|---|---|
| Density | 6 g/cm³ |
| Molar Mass/ Molecular Weight | 143.09 g/mol |
| B.P. (Boiling Point) | 1,800 °C |
| M.P. (Melting Point) | 1232 °C |
| Copper Oxide: Chemical Formula | Cu2O |
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| Related Articles | ||
|---|---|---|
| Calcination and Roasting | Ores and Minerals | Process Of Metallurgy |
| Concentration Of The Ore | Zone Refining | Reverberatory Furnace |
Chemical Properties of Copper Oxide
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- There is a very common reaction of Copper (I) Oxide. It is where the metal compound reacts with water and results in making Copper Hydroxide. The reaction for this chemical combination will explain it in the best manner. The reaction for the formation of Copper (II) Hydroxide is mentioned below,
2Cu2O + 4H2O + O2 → 4Cu(OH)2
- Another chemical reaction that Copper (I) Oxide is a part of is the formation of Copper (I) Chloride. This compound, Copper Chloride, is formed when Copper (I) Oxide is made to react with Hydrogen Chloride (HCl). This reaction involves the reduction of the oxygen in Copper (I) Oxide and the addition of Cl (Chlorine) atoms instead. This forms the compound Copper Chloride. The reaction for the above chemical combination is mentioned below,
Cu2O + 2HCl → 2CuCl + H2O
Physical Properties of Copper Oxide
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| Copper (I) Oxide: Physical Properties | |
|---|---|
| Appearance | Red in color |
| Odor | Odorless |
| Heavy Atom Count | 3 |
| Solubility | Not soluble in Water |
| The complexity | 2.8 |
| Covalently-Bonded Unit | 3 |
Colour of Copper Oxide (Explanation)
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Many find the color that Copper Oxide has is a bit misleading. The metallic oxide sometimes is red and at times is visible as extremely black colored. Thus Copper oxide can present itself to you in 2 different colors. These colors are,
- Red color for Copper (II) Oxide
- Black for Copper (I) Oxide
Uses of Copper Oxide
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There are many uses for the widely popular compound Copper Oxide. Some of these uses are mentioned in the points below,
- The bottom of a ship is very much prone to getting affected by seawater. To prevent it from any harm, coating the bottom is necessary. Therefore the bottom is coated with paint. Copper oxide is also utilized as paints (antifouling). This is based on the property of copper oxide to control corrosion.
- A portion of porcelain paints consists of Copper Oxide.
- Photocells also utilize copper oxide for the fabrication of rectifiers and light meters.
- Copper oxide is also brought into use as dressing for seeds and a fungicide.
- Copper oxide is also brought in use for the formation of superconductors, solar energy transformation, and semiconductors
How can one differentiate between Cupric Oxide and Cuprous Oxide?
Based on its valency, copper is capable of making different kinds of oxides. These oxides are namely Cuprous Oxide and Cupric Oxide. The Cupric Oxide has a color resembling brown. The Cuprous Oxide is red. When one of the atoms from the copper band gets attached to the oxygen molecule it makes a Cupric Oxide. When an oxygen atom gets attached to two of the copper atoms present then it results in the formation of Cuprous Oxide. Cuprous oxide is known to remain an act of state most of the time while cupric oxide is a fully oxidized state.
Preparation of Copper Oxide
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The preparation of copper can be done in three ways. These ways have been provided below,
- The widely used we to form Copper (I) Oxide is by the oxidation of the metal involved. That is, copper is oxidized. This takes place when copper is left in the air outside. It is usually a very slow process. It can even be parallelled with iron rusting. This process can be speeded up by the addition of water and other acids. It still is slow but far better than earlier. The equation involved in the process is mentioned below,
4Cu + O2 → 2Cu2O
- The commercial manufacturing of Copper (I) oxide is conducted by the use of Copper (II) Oxide. This process involves Copper (II) Oxide being put in a furnace siding with elemental copper. This triggers a redox reaction and Copper (I) Oxide is formed.
- The third process used to form Copper (I) oxide is electrolysis. An aqueous solution of sodium chloride undergoes electrolysis where copper electrodes are present.
Can Copper Oxide prove to be harmful to humans?
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To kill bacteria there is a need for molecules that are highly reactive and copper oxide is one such electron-deficient compound. Copper oxide also possesses the ability to get any pathogen present on the surface destroyed. Because Cuprous Oxide is highly unstable therefore it is more useful than cupric oxide for forming free radicals and killing pathogens. Therefore it can be safely said that while cuprous oxide may be toxic for bacteria it is very safe for humans. There are always exceptions. Too much of nothing is useful. Similar is the case with exposure to Copper Oxide.
Things of Remember
The Points to remember about Copper Oxide are,
- Copper oxide undergoes disproportion when introduced in acid solutions, therefore, resulting in copper and copper (II) ions. On gentle heating of cupric oxide in the presence of metallic copper, the resultant product is cuprous oxide.
- Copper Oxide is also very good corrosion-resistant. This property is a result of the surface reactions that carry out between the copper and oxygen present in the air which gives a protective layer of oxide.
- Copper oxide is available cheap when compared to other oxides available. It tends to get mixed with liquids that are polarized for example water and even with polymers. Other compounds have more stable physical and chemical properties.
- Metal oxides that are highly ionic and nanoparticulate, for example, CuO are prepared with the help of Cu2O. These act as useful agents in controlling microbial spoilage.
- Copper Oxide is mostly available as a powdered substance. This is mostly red. Therefore it is available to be produced as nanoparticles.
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Sample Questions
Ques. What are four very common uses of copper oxide? (4 marks)
Ans: The four very common uses of copper oxide are,
- A portion of porcelain paints consists of Copper Oxide.
- Photocells also utilize copper oxide for the fabrication of rectifiers and light meters.
- Copper oxide is also brought into use as dressing for seeds and a fungicide.
- Copper oxide is also brought in use for the formation of superconductors, solar energy transformation, and semiconductors
Ques. Are there any instances of Copper Oxide being harmful for Humans? (3 marks)
Ans: There is a limit to everything. Similar is with the exposure to Copper Oxide. Humans are not easily affected by Copper (II) Oxide but excessive exposure can lead to serious issues.
It can lead to cell death by harming important units of a cell like mitochondria and lysosome.
Ques. What makes Cuprous Oxide and Cupric Oxide different from each other? (4 marks)
Ans: There are not many ways to differentiate between Cupric and Cuprous Oxide because they have the same elements involved. But the few that matter are,
- Cupric Oxide is brown coloured on the other hand Cuprous Oxide is red in colour.
- In Cuprous Oxide, Copper is present as Cu+1 cation and in Cupric Oxide, Copper is present as Cu+2 cation.
- The formula for Cuprous Oxide is Cu2O and that of Cupric Oxide is CuO.
- Two copper atoms with one oxygen atom is Cuprous Oxide. And Cupric Oxide has one oxygen atom with one Copper atom.
Ques. What do you understand about Cuprous Oxide being soluble in water? (3 marks)
Ans: Cuprous Oxide exists as a solvent that is organic in nature. This makes it insoluble in water, thus it cannot be dissolved in water in all practicality. But, it can still be dissolved in aqueous solutions of other compounds like ammonia. Various ammonium salts are also capable of dissolving water.
Ques. Which Oxide of Copper shows more toxicity towards the bacterias? (3 marks)
Ans: The Copper oxide that is more toxic towards bacterias is Cuprous oxide. It is facilitated by the presence of one oxygen and two copper atoms in the compound. While, Cuprous Oxide is a form of Copper Oxide that's active, Cupric Oxide is more on the stable part. The toxicity of Cuprous Oxide is more because it has the ability to oxidise the cellular components' phosphate groups. These are the ones that are essential for carrying out cell metabolism. Therefore, once they are dysfunctional, the bacterial cells die. This makes Cu2O more toxic than CuO for the bacterias.
Ques. How does Copper Oxide get prepared? (3 marks)
Ans: There are three very common methods for the preparation of Copper Oxide. These are,
- Natural oxidation of copper in the presence of air containing oxygen. This is a slower process in comparison to others.
- Industrially, Copper Oxide is mostly prepared by heating elemental copper with Copper (II) Oxide.
- Third method involves the use of copper electrodes for electrolysis in the aqueous solution of NaCl (Sodium Chloride).
Ques. What are some well known physical properties to recognise Copper (I) Oxide? (4 marks)
Ans: Following are the physical properties for recognising Copper (I) Oxide,
- It is available in a powdered form.
- It is red in colour unlike the other Copper (II) Oxide.
- The powder is also odorless in nature.
- This oxide of copper finds itself not soluble in water.
Ques. Which Oxide of Copper, i.e., Cupric or Cuprous is more reactive than the other? (3 marks)
Ans: The more reactive metallic Oxide among Cuprous oxide and Cupric Oxide is Cuprous Oxide. This is because there are two copper atoms in Cuprous and only one in Cupric Oxide. This makes Cuprous Oxide have more electrons to donate and thus react because of its unstable nature. Cupric Oxide being fully oxidized is way more stable than a partially reduced Cuprous Oxide.
Ques. How is Copper Oxide involved in mineral extraction of copper? (3 marks)
Ans: Froth - Flotation is used to concentrate copper ore. When this ore undergoes roasting through the following reaction, Cu2O is obtained. The reaction is,
2Cu2S + 3O2 → 2Cu2O + 2SO2
Once Copper (I) Oxide is formed. It is then reacted with Cu2S in presence of heat to form SO2 and Blister Copper. The reaction involved is,
Cu2S + 2Cu2O → 6Cu + SO2.
This blister copper later undergoes electrolytic refining to produce pure copper.
Ques. A reddish brown coloured metal, used in electrical wires, when powdered and heated strongly in an open china dish its colour turns blacks. When hydrogen gas is passed over this black substance, it regains its original colour. Based on the above information, answer the following question.
(i) Name the metal and the black coloured substance formed.
(ii) Write a balanced chemical equation for both the equations. [CBSE 2012] (3 marks)
Ans: (i) The metal that appears to be reddish brown in the china dish is Copper. On heating it in the presence of oxygen it forms a metallic oxide of Copper. This oxide is Cupric Oxide or Copper (II) Oxide. This product is black coloured. The equation for this reaction is,
2Cu + O2 → 2CuO
(ii) On passing hydrogen over this product of Copper (II) Oxide, the resultant is Copper metal that's reddish brown in colour. The reaction involved is,
CuO + H2 → Cu + H2O
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