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Calcium oxide is a white, caustic alkaline which is solid at room temperature. Calcium Oxide is known as quicklime is a material which is a commonly used material. Calcium Oxide reactivity with water, along with its other chemical properties, makes it a very important chemical in various fields.
In this article, we will learn in detail about calcium oxide, its properties, applications, and other details in detail.
What is Calcium Oxide?
Calcium Oxide, also known as quicklime, lime water, or burnt lime, is a chemical compound with the formula CaO. Its common name is quicklime. Calcium oxide is composed of one calcium (Ca) atom and one oxygen (O) atom, with a chemical formula of CaO.
Calcium oxide has a high melting point of approximately 2,572 degrees Celsius (4,662 degrees Fahrenheit). It has a high density so it is a heavy substance.
Calcium Oxide Common Name
Common Name of Calcium Oxide is Quicklime.
Chemical Formula of calcium oxide is CaO.
Calcium Oxide Molecular Weight
Molecular weight of calcium oxide is approximately 56.08 amu.
Molecular Weight of Calcium Oxide can be obtained as
- Atomic weight of calcium is approximately 40.08 grams per mole (g/mol).
- Atomic weight of oxygen is approximately 16.00 g/mol.
Molecular Weight of CaO = Atomic Weight of Ca + Atomic Weight of O
⇒ Molecular Weight of CaO = 40.08 g/mol + 16.00 g/mol
⇒ Molecular Weight of CaO = 56.08 g/mol
Calcium Oxide Melting Point
Calcium oxide has a very high melting point.
Calcium Oxide Melting Point is approximately 2572℃ (4662℉)
This high melting point is characteristic of many ionic compounds, and it reflects the strong electrostatic forces of attraction between the positively charged calcium ions and the negatively charged oxide ions in the crystal lattice of the solid CaO.
Structure of CaO Molecules
Calcium oxide molecules contain one calcium cation (which holds a charge of +2) and one oxygen anion (which holds a charge of -2).
Lewis Dot Structure of Calcium Oxide
Lewis dot structure of calcium oxide (CaO) is drawn by considering the valence electrons of each element and their bonding.
- Calcium (Ca) is in Group 2 of the periodic table, so it has 2 valence electrons.
- Oxygen (O) is in Group 16 of the periodic table, so it has 6 valence electrons.
In this structure, the two oxygen atoms are bonded to the calcium atom via double bonds, and each oxygen atom has a full octet of electrons, while calcium has lost two electrons to achieve a stable electron configuration.
The formula for lime water is Ca(OH)2 and the chemical name for lime water is calcium hydroxide. When water is added to lime calcium hydroxide Ca(OH)2 is formed according to the following reaction.
CaO + H2O → Ca(OH)2
Preparation of Calcium Oxide
Calcium oxide is prepared by the process called calcination. Calcination involves heating calcium carbonate (CaCO3) to a high temperature, causing it to decompose and release carbon dioxide (CO2), leaving behind calcium oxide (CaO) as the final product.
CaCO3(g) → CaO(s) + CO(g)
Sources of Calcium Carbonate: It can be obtained naturally i.e. occurring in minerals such as limestone, chalk, or marble.
Physical Properties of Calcium Oxide
The physical properties of calcium oxide are essential to understand its behavior and applications in various fields.
- Appearance: CaO is a white, odorless, and crystalline solid at room temperature. It is typically found in the form of small white or grayish-white crystals or a fine powder.
- Melting Point: CaO has a high melting point of approximately 2,572 degrees Celsius (4,662 degrees Fahrenheit).
- Hygroscopic: This property makes it essential to store quicklime in a dry environment and in airtight containers to prevent its reaction with water.
- Crystal Structure: The crystal structure of calcium oxide is often described as being cubic or face-centered cubic (FCC).
- High Electrical Conductivity: CaO, in its molten state or in the presence of water, exhibits high electrical conductivity.
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Properties
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Value
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| Molar Mass |
56.0774 g/mol |
| Boiling Point |
2,850 °C |
| Melting Point |
2,572 °C |
| Density |
3.34 g/cm³ |
Chemical Properties of Calcium Oxide
Calcium oxide exhibits wide range of chemical properties and some of its important chemical properties includes:
Reactivity with Water
Calcium oxide is highly reactive with water, and when it comes in contact with water, it undergoes a vigorous exothermic reaction. This reaction results in the formation of calcium hydroxide [Ca(OH)2] and the release of a significant amount of heat. The equation for this reaction is
CaO + H2O → Ca(OH)2
- Carbonation: Calcium oxide can absorb carbon dioxide from the atmosphere, converting back into calcium carbonate (CaCO3).
- Desiccant Properties: Calcium oxide is a strong desiccant, meaning it has a strong affinity for moisture. It can be used to remove water from gases and liquids, making it valuable in drying applications, including the removal of moisture from industrial processes.
- Reactivity with Carbon: Calcium oxide when heated in the presence of carbon, reduces carbon dioxide to produce carbon monoxide.
- Electrolysis: In molten form or in the presence of water, calcium oxide exhibits electrical conductivity. This property can be used in processes like the electrolysis of metals.
- Strong Alkalinity: Calcium oxide is a strong alkaline compound which has the ability to increase the pH of solutions, making it useful in applications where alkalinity is required.
- Reduction Reactions: Calcium oxide can also behave as a reducing agent, participating in various reduction reactions.
Calcium Oxide Chemical Reactions
Calcium oxide undergoes various chemical reactions due to its high reactivity but some of the most common reactions of calcium oxide are:
When calcium oxide reacts with chlorine gas (Cl2), it can form calcium hypochlorite [Ca(ClO)2], a compound often used in water treatment and as a bleaching agent.
CaO + Cl2 → Ca(ClO)2
Uses of Calcium Oxide
Calcium oxide is a versatile compound having many applications across various industries. Some of its common uses are:
- Chemical Industry: It is used as a precursor in the production of various chemicals, such as calcium stearate, used in the manufacture of plastics and soaps.
- Metallurgy: In the metallurgical industry, calcium oxide is used to remove impurities and slag during the extraction of metals from ores.
- Water Treatment: Calcium oxide can be used for water softening by removing excess calcium and magnesium ions that causes water hardness.
- Construction Industry: Calcium oxide is a fundamental ingredient in the production of mortar and plaster.
- Environmental Impact: Calcium oxide plays a crucial role in resolving environmental issues like improvement in air quality, improvement in water quality , agricultural sustainability, etc.
- Metallurgy: In the extraction of metals from ores, calcium oxide is used to remove impurities.
Danger of Calcium Oxide
Calcium oxide, also known as quicklime or burnt lime, is a widely used chemical compound with significant industrial applications. However, it poses several health and safety risks. Here are some key dangers associated with calcium oxide:
Corrosive Nature
- Skin Contact: Calcium oxide is highly corrosive. Direct contact with skin can cause severe irritation, chemical burns, and blistering. It reacts exothermically with water, including moisture on the skin, producing heat and further enhancing its corrosive effects.
- Eye Contact: If calcium oxide comes into contact with the eyes, it can cause severe irritation, burns, and even permanent eye damage, including blindness.
Respiratory Hazards
- Inhalation: Breathing in calcium oxide dust can irritate the respiratory tract, leading to coughing, sneezing, and shortness of breath. Prolonged exposure can result in more serious respiratory issues, such as pneumonitis, a condition characterized by inflammation of lung tissue.
Chemical Burns
- Moisture Reaction: When calcium oxide comes into contact with water, it reacts vigorously, generating heat and forming calcium hydroxide. This exothermic reaction can cause thermal burns in addition to chemical burns.
Environmental Impact
- Soil and Water: If released into the environment, calcium oxide can alter the pH of soil and water bodies, potentially harming plants and aquatic life. It can also contribute to the alkalinization of soils, which can affect plant growth.
Fire Hazard
- Reactivity: Although calcium oxide itself is not flammable, it can react with water to produce heat. If it comes into contact with organic materials, the heat generated can ignite these materials, posing a fire risk.
Incompatibility with Other Chemicals
- Reactive Substances: Calcium oxide can react violently with acids, generating heat and potentially dangerous fumes. It also reacts with certain metals and organic materials, which can lead to hazardous conditions.
Safety Tips
- Reaction between quicklime and water is vigorous.
- Quicklime can cause irritation, especially when inhaled or if it comes in contact with wet skin or eyes.
- Some of the effects of inhalation include sneezing, coughing, or laboured breathing.
- Also, it can result in abdominal pain, nausea burns with perforation of the nasal septum, and vomiting.
- When quicklime reacts with water it release heat to combustible materials.
Also, check
Comparison with Similar Calcium Compounds:
- Calcium Hydroxide (Ca(OH)₂):
Formation: Made by the digestion of calcium oxide with water.
Properties: This one is still less reactive compared to the former chemical, and is only slightly soluble in water to form what is known as limewater.
Uses: These are in water treatment, as a neutralizing agent, construction and for other uses as dehydrating agent.
- Calcium Carbonate (CaCO₃):
Formation: It is naturally obtained from limestone, chalks as well as marble.
Properties: Stable sch as CaO and less reactive compared to Calcium oxide. It has heat effects of decomposition; subslimates to form calcium oxide and carbon dioxide when heated.
Uses: Not only in construction but also in the preparation of cement, in the manufacture of cement, and as a type of food supplement.
Formation: Obtained from the burning of calcium oxide with sulfur dioxide.
Properties: In the form of dihydrate, which is gypsum, reacts as a reagent, not as calcium oxide which is highly reactive.
Uses: Applied to a plaster, drywall and as a conditioner to the soil.
Sample Questions on Calcium Oxide
Question 1: What is the Chemical Formula of Oxide?
Answer:
Chemical Formula of Calcium Oxide is CaO.
Question 2: How Calcium oxide is prepared?
Answer:
Calcium oxide is prepared by the process called calcination which involves heating the calcium carbonate (CaCO3) at high temperature, causing it to decompose and release carbon dioxide (CO2), leaving behind calcium oxide (CaO).
CaCO3(g)→CaO(s) + CO(g)
Question 3: What is the primary use of calcium oxide in industry?
Answer:
The primary use of calcium oxide in the industry is in the production of cement. Calcium oxide plays an important in the manufacturing of Portland cement, which is the most widely used type of cement in construction and building applications.
Question 4: What is the state of calcium oxide at room temperature?
Answer:
Calcium oxide is a solid at room temperature.
FAQs on Calcium Oxide
What is Calcium Oxide?
Calcium oxide is a white crystalline substance(an inorganic compound) having chemical formula CaO and is also known as quicklime.
Who Discovered Calcium oxide?
Calcium oxide was initial discovered by the French chemist Joseph Black’s in the middle of the eighteenth century. Joseph Black carried out experiments that he used to isolate this compound, which he referred to as “calcareous alkali.” His experimentation on calcium oxide formed part of his lime and carbon dioxide studies.
What are Sources of Calcium Carbonate?
It is basically found in natural minerals such as limestone, chalk, or marble.
Calcium oxide reacts vigorously with water to produce calcium hydroxide [Ca(OH)2] and significant amount of heat is released.
CaO + H2O → Ca(OH)2 + Heat
How can Calcium Oxide improves Air and Water Quality?
Calcium Oxide captures sulfur dioxide which helps to reduce acid rain formation and air pollution, contributing to improved air quality and reduced environmental harm and it also aids in improving water quality by reducing hardness and the presence of heavy metals, making it safer for consumption and industrial use.
Why Calcium Oxide is used in Alkaline Battery Production?
Calcium oxide is used as an important component in alkaline batteries, where it helps to regulate the pH of the battery electrolyte.
Is Calcium Oxide Soluble in Water?
Calcium oxide is only sparingly soluble in water. When calcium oxide is added to water, it undergoes a vigorous exothermic reaction to produce calcium hydroxide [Ca(OH)2].
Is Calcium Oxide Ionic or Covalent?
Calcium oxide is an ionic compound. It is formed by the combination of a metal (calcium) and a non-metal (oxygen).
Does calcium oxide dissolve in water?
Calcium oxide (CaO) when come in contact with water, it undergoes a reaction that reacts with water to form calcium hydroxide (Ca(OH)₂) and this reaction is exothermic. Calcium hydroxide is relatively insoluble in water; it forms limewater.
What is Reaction of Water with Calcium oxide?
This reaction results in the formation of calcium hydroxide [Ca(OH)2] and the release of a significant amount of heat. The equation for this reaction is CaO + H2O → Ca(OH)2
Why is calcium important for bones?
Calcium is important for bones because bones need calcium to be strong and rigid. Some of the important functions include formation of bone and support of bone density being an essential element in the process. Sufficient calcium consumes strengthens the bones and lowers the likelihood of bone fractures as well as other diseases such as osteoporosis.
Can you drink Limewater?
Lime water which is a solution of calcium hydroxide in water can be taken sometimes, in small proportions, because of medical purposes such as those that involve acid indigestion. However, the moderate or frequent use is disapproved due to the impact that is deemed to be negative. These products are prohibited from being sold if people do not consult a doctor. As for the choice of fluids, it is possible to drink plain water or the beverages suggested above for satisfying one’s hydration needs.
What are the two uses of quicklime?
Quicklime has a variety of uses:
Agriculture: Applied to improve soil pH and as a soil conditioner.
Water Treatment: Helps to soften water and remove impurities in municipal and industrial water treatment.
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