Discover the physical and chemical properties of calcium hydroxide and explore its diverse range of uses in our informative notes on Calcium Hydroxide.
Calcium Hydroxide: The Nature of Slaked Lime
- Calcium hydroxide, commonly known as slaked lime, is denoted by the chemical formula Ca(OH)2.
- In its solid state, this inorganic compound presents itself as a white, powdery substance. However, its crystalline form appears colorless.
Other Names and Preparation
- This compound is also recognized by various names such as hydrated lime, slack lime, pickling lime, and caustic lime.
- Typically, the preparation of calcium hydroxide involves the combination of water with calcium oxide, also referred to as quick lime.
- Another method involves a chemical reaction between sodium hydroxide and calcium chloride in aqueous CaCl2.
Molecular Structure
- The molecular structure of Ca(OH)2 involves the bonding of calcium ions (Ca2+) with two hydroxide ions (OH–) through ionic bonds. This arrangement forms the stable calcium hydroxide molecule.
Safety Considerations
- Caution is advised when handling calcium hydroxide as unprotected exposure can pose risks. It has the potential to irritate the skin and chemical burns.
- Exposure to concentrated Ca(OH)2 can result in severe consequences such as lung damage and, in extreme cases, even blindness. Understanding and implementing proper safety measures are crucial when dealing with this compound.
Properties of Calcium Hydroxide
| Chemical Formula | Ca(OH)2 |
| IUPAC name | Calcium Hydroxide |
| Molecular Weight/Molar Mass | 74.093 grams per mole |
| Density | 2.211 grams per cubic centimetre |
| Appearance | White powder or colourless crystal |
| Melting Point | 853 K |
Physical Characteristics of Calcium Hydroxide
Crystal Structure
The crystal structure of Ca(OH)2 is characterized by a hexagonal arrangement.
Solubility in Water
Calcium hydroxide exhibits limited solubility in water, and this solubility diminishes as the temperature rises.
For instance, at 0°C, its solubility is 1.89 g/L, and at 20°C, it further decreases to 1.73 g/L.
Thermal Behavior
As temperatures approach the melting point, Ca(OH)2 tends to undergo dehydration, releasing water and decomposing in the process.
Solubility Product
The solubility product (Ksp) of calcium hydroxide is recorded at 5.5 × 10-6, indicating the equilibrium constant for its limited solubility in aqueous solutions. Understanding these physical properties is crucial for comprehending the behavior of calcium hydroxide under different conditions.
Chemical Behavior of Calcium Hydroxide
Solubility in Various Solvents
While calcium hydroxide exhibits notable solubility in glycerol and acids, its solubility in water is relatively limited.
Formation of Limewater
When dissolved in water to its saturation point, calcium hydroxide produces a solution known as limewater. This solution behaves as a moderate base and is commonly utilized in various chemical processes.
Reactivity with Acids
Limewater, derived from calcium hydroxide, reacts with acids to produce salts. This chemical interaction exemplifies the compound’s acidic neutralization properties.
Interaction with Metals
The saturated solution of calcium hydroxide in water displays reactivity with metals, including metals like aluminum, leading to the dissolution and formation of corresponding salts.
Carbonatation Reaction
In the presence of carbon dioxide, calcium hydroxide undergoes a reaction known as carbonatation, resulting in the formation of calcium carbonate (CaCO3).
This chemical transformation is essential in various industrial processes and contributes to the compound’s versatile applications.
Read More: Calcium Carbonate, Formula, Properties, Uses, Application
Applications of Calcium Hydroxide
Sewage Treatment
In sewage treatment, calcium hydroxide plays a crucial role as a clarifying agent and flocculant, aiding in the removal of impurities.
Paper Industry
The paper industry utilizes Ca(OH)2 in the Kraft process, where it contributes to the conversion of wood into wood pulp.
Ammonia Production
Calcium hydroxide is a vital component in the preparation of ammonia, contributing to the synthesis of this essential chemical compound.
pH Modification
Due to its basic properties, Ca(OH)2 serves as a pH modifier in various applications, helping to adjust acidity levels.
Pickling Agent
The pickling of cucumbers involves the use of Ca(OH)2, contributing to the preservation and flavor enhancement of this popular food item.
Plastics Production
In the manufacturing of plastics, calcium hydroxide is employed as an ingredient, playing a role in the production of diverse plastic materials.
Diverse Industries
Its applications extend to pesticides, hair care products, and the production of ebonite, showcasing its versatility in different industrial processes.
Dental Procedures
In dentistry, specifically in root canal procedures, calcium hydroxide is utilized to fill cavities in human teeth.
Sugar Processing
Sugar beets and sugarcane undergo processing through carbonation, a process that involves the use of Ca(OH)2.
Leather Industry
In the leather industry, calcium hydroxide is employed to separate fur/hair from animal hides, contributing to the leather processing procedures. Understanding these varied applications underscores the significance of calcium hydroxide across diverse industrial sectors.
Frequently Asked Questions (FAQs) About Calcium Hydroxide
Q1. What are the common uses of calcium hydroxide?
Calcium hydroxide, a white powder without a distinct odor, finds application in various industries. It is utilized in waste treatment, paper manufacturing, construction, and food processing, and has medical and dental applications. For example, it is often present in fillings used during root canal treatments.
Q2. Is calcium hydroxide acidic or basic?
Calcium hydroxide, also known as slaked lime (Ca(OH)2), acts as a base. When dissolved in water, it releases hydroxide ions (OH-) due to electrolyte dissociation.
Q3. How is calcium hydroxide prepared?
Calcium hydroxide is produced by combining water with calcium oxide, also called slaked lime (Ca(OH)2). This process results in the formation of a solution known as limewater, along with a suspension called lime milk.
Q4. Is calcium hydroxide ionic or covalent?
Calcium hydroxide has an ionic structure.
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