Calcium hydroxide (Ca(OH)2) is a chemical compound used in various applications such as food production, water treatment, and construction. It is made by mixing calcium oxide with water and has a white, powdery appearance.
| IUPAC name | Calcium hydroxide |
| Molecular formula | Ca(OH)2 |
| CAS number | 1305-62-0 |
| Synonyms | Slaked lime, hydrated lime, milk of lime, pickling lime |
| InChI | InChI=1S/Ca.2H2O/h;2*1H2/q+2;;/p-2 |
Calcium Hydroxide Properties
Calcium Hydroxide Formula
The chemical formula for calcium hydroxide is Ca(OH)2. This means that each molecule of calcium hydroxide contains one Ca2+ ion and two OH- ions. The formula is important in chemistry, as it represents the number and types of atoms in a compound.
Calcium Hydroxide Molar Mass
Ca(OH)2 has a molar mass of 74.09 g/mol. It is made up of one calcium atom, two oxygen atoms, and two hydrogen atoms. Molar mass is an important property in chemistry, as it is used to calculate the amount of a substance in a given sample.
Calcium Hydroxide Boiling Point
Ca(OH)2 has a very high boiling point of 2,400°C. This means that it requires a significant amount of heat to convert it from a liquid to a gas. The high boiling point is due to the strong ionic bonds between the calcium and hydroxide ions.
Calcium Hydroxide Melting Point
Ca(OH)2 has a relatively low melting point of 580°C. This means that it can be easily melted and molded into various shapes. The low melting point is due to the ionic nature of the compound, which allows the ions to move more freely when heated.
Calcium Hydroxide Density g/mL
The density of Ca(OH)2 is 2.24 g/mL. This means that it is a relatively heavy compound, as compared to water which has a density of 1 g/mL. The high density is due to the tightly packed nature of the Ca2+ and OH- ions.
Calcium Hydroxide Molecular Weight
The molecular weight of Ca(OH)2 is 74.09 g/mol. This is the sum of the atomic weights of the calcium, oxygen, and hydrogen atoms in the compound. Molecular weight is an important property in chemistry, as it is used to calculate various parameters such as molarity and percent composition.
Calcium Hydroxide Structure
Ca(OH)2 has a crystal structure, with each calcium ion surrounded by six hydroxide ions in an octahedral arrangement. This structure gives the compound its characteristic white, powdery appearance. The ionic bonds between the Ca2+ and OH- ions are strong, which gives the compound its high melting and boiling points.
| Appearance | White powder |
| Specific Gravity | 2.24 g/cm³ |
| Color | White |
| Odor | Odorless |
| Molar Mass | 74.09 g/mol |
| Density | 2.24 g/cm³ |
| Melting Point | 580 °C |
| Boiling Point | 2,400 °C |
| Flash Point | Not applicable |
| Water Solubility | 1.7 g/L (20 °C) |
| Solubility | Soluble in acids |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | 12.5 (first dissociation) |
| pH | 12.5 (0.1 M solution, 25 °C) |
Calcium Hydroxide Safety and Hazards
Ca(OH)2 is generally considered safe when handled properly. However, it can be hazardous if ingested, inhaled, or comes into contact with the skin or eyes. It can cause irritation, burns, and respiratory problems. Dust from the compound can also irritate the respiratory system. Protective equipment such as gloves, goggles, and respirators should be worn when handling Ca(OH)2. The compound should also be stored in a cool, dry, well-ventilated area away from incompatible materials. In case of contact or ingestion, seek medical attention immediately.
| Hazard Symbols | Xi (Irritant) |
| Safety Description | Wear protective gloves and eye/face protection. |
| UN IDs | UN 1910 |
| HS Code | 2825.90.90 |
| Hazard Class | 8 – Corrosive substances |
| Packing Group | III |
| Toxicity | Calcium hydroxide is generally considered to be non-toxic when handled properly. However, ingestion or inhalation can irritate and burns the respiratory system and digestive tract. |
Calcium Hydroxide Synthesis Methods
Various methods can synthesize Ca(OH)2.
One common method for synthesizing Ca(OH)2 is to react water with calcium oxide, resulting in the formation of slaked lime or hydrated lime.
Another method involves the reaction of calcium chloride with sodium hydroxide. The reaction of water and carbon dioxide with calcium carbonate produces Ca(OH)2.
The process of hydration involves mixing water with calcium oxide in the slaked lime method. This reaction produces Ca(OH)2 and heat as a byproduct. The process further removes impurities and excess water from the resulting paste.
The calcium chloride method involves mixing calcium chloride and sodium hydroxide through a process known as double decomposition.
This reaction produces Ca(OH)2 and sodium chloride as byproducts. The resulting Ca(OH)2 is then purified and dried.
In the calcium carbonate method, calcium carbonate is first heated to produce calcium oxide and carbon dioxide. The process of hydration involves mixing calcium oxide with water, which produces Ca(OH)2.
Calcium Hydroxide Uses
Ca(OH)2 has many uses in various industries, including:
- Construction: Used as a key component in the production of concrete, mortar, and stucco due to its ability to strengthen and increase the durability of these materials.
- Agriculture: Used as a soil amendment to reduce soil acidity and improve soil fertility.
- Water treatment: Used to soften water by removing impurities such as magnesium and calcium ions.
- Chemical manufacturing: Used in the production of various chemicals such as calcium stearate, calcium hypochlorite, and calcium phosphate.
- Food industry: Used as a food additive to regulate acidity levels in food products such as pickles, olives, and soft drinks.
- Medical industry: Used in various dental procedures, such as root canal treatments and cavity fillings, due to its antimicrobial and antifungal properties.
- Pulp and paper industry: Used in the production of paper to improve the brightness and strength of the paper.
- Leather industry: Used in the processing of leather to remove hair and impurities.
Questions:
Q: Is calcium hydroxide soluble?
A: Ca(OH)2 is moderately soluble in water, with a solubility of about 1.2 g/L at room temperature.
Q: What is the formula for calcium hydroxide?
A: The formula for calcium hydroxide is Ca(OH)2.
Q: Where to buy calcium hydroxide near me?
A: Ca(OH)2 can be purchased at chemical supply stores, hardware stores, or online retailers. You can search for nearby chemical supply stores or hardware stores in your area or check online retailers such as Amazon or eBay.
Q: Is Ca(OH)2 an acid or base?
A: Ca(OH)2 is a base. It is a strong base that dissociates completely in water to form calcium ions (Ca2+) and hydroxide ions (OH-).
Q: When the reaction H3PO4(aq)+Ca(OH)2(aq)→ occurs, what is the formula for the salt formed?
A: The reaction between H3PO4(aq) and Ca(OH)2(aq) produces calcium phosphate (Ca3(PO4)2) and water (H2O) as the salt and byproduct, respectively.
Q: Is Ca(OH)2 soluble in water?
A: Yes, Ca(OH)2 is moderately soluble in water. It can dissolve in water to form a saturated solution with a concentration of approximately 1.2 g/L at room temperature.
Q: Is Ca(OH)2 a strong base?
A: Yes, Ca(OH)2 is a strong base. It is a highly basic compound that dissociates completely in water to form Ca2+ and OH- ions, making it a strong base.
Q: Which are produced when HCl reacts with Ca(OH)2?
A: When HCl reacts with Ca(OH)2, the products formed are calcium chloride (CaCl2) and water (H2O), as the H+ ions from HCl react with the OH- ions from Ca(OH)2 to form water, while the remaining Ca2+ and Cl- ions form the salt, calcium chloride.