Calcium Hydroxide Formula 

Calcium Hydroxide Formula

Calcium hydroxide, also known as slaked lime or hydrated lime, has the chemical formula Ca(OH)2. It is composed of one calcium ion (Ca2+) and two hydroxide ions (OH-) bonded together.

The molecular structure of calcium hydroxide consists of a calcium cation (Ca2+) surrounded by two hydroxide anions (OH-). The calcium ion is located at the center, while the hydroxide ions are positioned around it. Each hydroxide ion consists of one oxygen atom bonded to one hydrogen atom.

Physical properties of Calcium Hydroxide

• Appearance: Calcium hydroxide is a white, crystalline powder or solid. It can also appear as a colorless or slightly off-white substance.
• Odor: It has a characteristic odor, which is slightly sweet and alkaline.
• Solubility: Calcium hydroxide is sparingly soluble in water, meaning it dissolves only to a limited extent. However, its solubility increases with temperature.
• Density: The density of calcium hydroxide is approximately 2.21 grams per cubic centimeter (g/cm³).
• Melting Point: Calcium hydroxide has a high melting point of around 580 degrees Celsius (1076 degrees Fahrenheit).

Chemical properties of Calcium Hydroxide

• Alkalinity: Calcium hydroxide is a strong base and exhibits alkaline properties. When dissolved in water, it dissociates to release hydroxide ions, which can react with acids to form salts and water.
• Reactivity: Calcium hydroxide reacts readily with carbon dioxide (CO2) in the atmosphere to form calcium carbonate (CaCO3). This process is known as carbonation and is responsible for the hardening and stabilization of calcium hydroxide in construction materials such as mortar and plaster.
• pH: When calcium hydroxide dissolves in water, it forms a basic or alkaline solution. The pH of a saturated calcium hydroxide solution is around 12-13.
• Hygroscopicity: Calcium hydroxide has hygroscopic properties, meaning it has a tendency to absorb moisture from the atmosphere. This can lead to the formation of a damp or sticky layer on the surface of the substance.

Calcium hydroxide is widely used in various applications

1. Construction: It is used in the production of cement, mortar, and plaster, where it acts as a binder and improves the strength and durability of these materials.
2. Water Treatment: Calcium hydroxide is employed in water and wastewater treatment processes to raise the pH and remove impurities through precipitation reactions.
3. Agriculture: It is used as a soil amendment to adjust soil pH and provide essential nutrients to crops.
4. Food Industry: Calcium hydroxide is used in food processing, particularly for food preservation and as a firming agent in pickling and canning.

In summary, calcium hydroxide with the formula Ca(OH)2 is a white crystalline powder. It is sparingly soluble in water and exhibits alkaline properties. Calcium hydroxide has several applications in construction, water treatment, agriculture, and the food industry.

Solved Examples on Calcium hydroxide Formula

Example 1: How many hydroxide ions are present in one formula unit of calcium hydroxide?

Answer: The formula of calcium hydroxide is Ca(OH)2. This means that there are two hydroxide ions (OH-) present in one formula unit of calcium hydroxide.

Example 2: What is the charge of the calcium ion in calcium hydroxide?

Answer: In calcium hydroxide, the hydroxide ion (OH-) has a charge of -1. Since there are two hydroxide ions in the formula, the total charge of the hydroxide ions is -2. In order to balance the charges, the calcium ion (Ca2+) must have a charge of +2. Therefore, the calcium ion in calcium hydroxide has a charge of +2.

In summary, one formula unit of calcium hydroxide (Ca(OH)2) contains two hydroxide ions and one calcium ion with a charge of +2.

Frequently Asked Questions on Calcium Hydroxide Formula

What is the chemical formula for calcium hydroxide?

The chemical formula for calcium hydroxide is Ca(OH)2. It consists of one calcium atom and two hydroxide groups, reflecting its composition.

What is the common name for calcium hydroxide?

The common name for calcium hydroxide is slaked lime or hydrated lime. It's often used in construction and various other industries due to its properties.

How is calcium hydroxide formula formed?

Calcium hydroxide formula, Ca(OH)2, is formed when calcium oxide (CaO) reacts with water (H2O). The water molecules break apart and attach to the calcium atom, forming two hydroxide groups.

Why does calcium hydroxide have 2 OH?

Calcium hydroxide has two hydroxide (OH) groups because calcium has a +2 charge, which balances out with the two -1 charged hydroxide ions, making the compound neutral.

Is calcium hydroxide used in soap?

Yes, calcium hydroxide is used in soap-making. It acts as an alkali that helps in saponification, the process that turns fats and oils into soap.

What is the main use of calcium hydroxide?

The main use of calcium hydroxide is in construction, where it's used to make mortar and plaster. It also finds applications in water treatment, food preparation, and various chemical processes.

Which chemical is used for whitewashing?

Calcium hydroxide is the chemical traditionally used for whitewashing. When mixed with water, it forms a white paste that can be applied to walls and ceilings to give them a fresh, clean appearance.

What is another name for calcium hydroxide?

Another name for calcium hydroxide is slaked lime. Besides, it is also referred to as hydrated lime, lime water, or pickling lime in different contexts and uses.