Calcium nitrite (Ca(NO2)2) is a chemical compound that is commonly used as a corrosion inhibitor in concrete. It helps to prevent the corrosion of steel reinforcement.
| IUPAC name | Calcium dinitrite |
| Molecular formula | Ca(NO2)2 |
| CAS number | 13780-06-8 |
| Synonyms | Calcium Nitrite Dihydrate, Nitrous acid, calcium salt, Nitric acid, calcium salt, dihydrate, etc. |
| InChI | InChI=1S/Ca.2HNO2/c;22-1-3/h;2(H,2,3) |
Calcium Nitrite Properties
Calcium Nitrite Formula
The chemical formula for calcium nitrite is Ca(NO2)2. This formula indicates that the compound contains two nitrite anions for every calcium cation. The formula is important for determining the composition of the compound and for determining the amount of each element in the compound.
Calcium Nitrite Molar Mass
The molar mass of Ca(NO2)2, also known as calcium dinitrite, is approximately 132.09 g/mol. It is an ionic compound made up of calcium cations and nitrite anions. The molar mass is calculated by adding the atomic masses of the constituent elements in the compound, which in this case are calcium, nitrogen, and oxygen.
Calcium Nitrite Boiling Point
Ca(NO2)2 has a high boiling point of approximately 400°C (752°F). This high boiling point is due to the strong ionic bonds that exist between the Ca2+ and NO2- ions in the compound. When Ca(NO2)2 is heated, it undergoes thermal decomposition, releasing nitrogen dioxide and oxygen.
Calcium Nitrite Melting Point
Ca(NO2)2 has a melting point of approximately 132°C (270°F). This melting point is relatively low compared to other ionic compounds, such as sodium chloride, which has a melting point of 801°C (1,474°F). The low melting point of Ca(NO2)2 can be attributed to the relatively weak ionic bonds that exist between the Ca2+ and NO2- ions.
Calcium Nitrite Density g/mL
The density of Ca(NO2)2 is approximately 2.32 g/mL. This value indicates that Ca(NO2)2 is a relatively dense compound. The density is calculated by dividing the mass of the compound by its volume. The high density of Ca(NO2)2 can be attributed to the presence of calcium cations, which are relatively heavy.
Calcium Nitrite Molecular Weight
The molecular weight of Ca(NO2)2 is approximately 132.09 g/mol. This value is calculated by adding the atomic weights of the constituent elements in the compound. The molecular weight is important for determining the amount of Ca(NO2)2 needed to obtain a certain number of moles of the compound.
Calcium Nitrite Structure
The structure of Ca(NO2)2 is composed of Ca2+ and NO2-. The Ca2+ ions are located at the center of the crystal lattice, while the NO2- ions surround them. The crystal lattice is held together by strong ionic bonds between the Ca2+ and NO2- ions.
Calcium Nitrite Solubility
Ca(NO2)2 is soluble in water and alcohol. The solubility in water is relatively high, with a solubility of approximately 61 g/100 mL of water at room temperature. The solubility in alcohol is lower than in water. The solubility of Ca(NO2)2 is important for determining its use in various applications, such as in the production of concrete.
| Appearance | White to slightly yellow crystalline powder or solid |
| Specific Gravity | 2.32 |
| Color | Colorless to white |
| Odor | Odorless |
| Molar Mass | 132.09 g/mol |
| Density | 2.32 g/mL |
| Melting Point | 132 °C (270 °F) |
| Boiling Point | Decomposes at approximately 400 °C (752 °F) |
| Flash Point | Not applicable |
| Water Solubility | Soluble |
| Solubility | Soluble in water and alcohol |
| Vapor Pressure | Not applicable |
| Vapor Density | Not applicable |
| pKa | Not applicable |
| pH | Neutral |
Calcium Nitrite Safety and Hazards
Ca(NO2)2 can be harmful if ingested, inhaled, or in contact with the skin or eyes. It can cause irritation, burns, and respiratory problems. The compound is also an oxidizing agent and can react with other chemicals, such as acids and metals, to form hazardous substances. Ca(NO2)2 should be stored in a cool, dry, and well-ventilated area, away from incompatible materials. Personal protective equipment, such as gloves and goggles, should be worn when handling the compound. In case of exposure, immediate medical attention should be sought, and contaminated clothing should be removed.
| Hazard Symbols | Xn |
| Safety Description | Avoid contact with skin and eyes; wear personal protective equipment (PPE); in case of exposure, seek medical attention immediately |
| UN IDs | UN 1454 |
| HS Code | 2834.29.90 |
| Hazard Class | 5.1 |
| Packing Group | III |
| Toxicity | Harmful if ingested or inhaled; can cause irritation, burns, and respiratory problems |
Calcium Nitrite Synthesis Methods
Various methods can synthesize Ca(NO2)2, including reacting nitric acid or nitrogen oxides with calcium carbonate, reacting nitrous acid or nitrogen oxides with calcium hydroxide, and reacting calcium hydroxide or ammonium hydroxide with calcium nitrate.
One common method involves reacting calcium carbonate with nitric acid to produce calcium nitrate. Then, reacting calcium nitrate with calcium hydroxide results in the formation of Ca(NO2)2 and byproducts of calcium oxide.
Another method involves the reaction of nitrogen oxides with calcium hydroxide to produce Ca(NO2)2 and calcium nitrate.
In another method, one can react calcium nitrate with calcium hydroxide or ammonium hydroxide to produce Ca(NO2)2 while generating calcium nitrate as a byproduct.
Calcium Nitrite Uses
Ca(NO2)2 has a variety of applications across different industries, including:
- Concrete industry: Used as a concrete additive to increase the durability and strength of concrete structures. It acts as a corrosion inhibitor by protecting the reinforcing steel from corrosion caused by chlorides and other aggressive ions.
- Agriculture: Used as a fertilizer in agriculture to provide a source of nitrogen and calcium to plants. Also used as a soil conditioner to improve soil quality and enhance plant growth.
- Chemical industry: Used as a reducing agent in chemical reactions, as well as a precursor for the synthesis of other chemicals such as calcium nitrate and calcium ammonium nitrate.
- Wastewater treatment: Used as a wastewater treatment chemical to remove contaminants and reduce the concentration of harmful substances in water.
- Food industry: Used as a food preservative to prevent the growth of bacteria and other microorganisms in meat, fish, and other food products.
Questions:
Q: What is the formula for calcium nitrite?
A: The chemical formula for calcium nitrite is Ca(NO2)2.
Q: How much calcium nitrite is used in concrete annually?
A: The amount of Ca(NO2)2 used in concrete annually varies depending on the specific application and market demand. However, it is estimated that several thousand metric tons of Ca(NO2)2 are used globally each year as a concrete additive.
Q: Is calcium nitrite soluble in water?
A: Yes, Ca(NO2)2 is soluble in water. It has a solubility of approximately 167 g/L at 20°C.
Q: Is calcium nitrite a salt?
A: Yes, Ca(NO2)2 is salt. An ionic compound composed of calcium cations (Ca2+) and nitrite anions (NO2-).
Q: How would the following solutions be prepared? 1.25 l of a 0.775 m solution of Ca(NO2)2
A: To prepare 1.25 L of a 0.775 M solution of Ca(NO2)2, one would need to dissolve approximately 187.5 g of Ca(NO2)2 in enough water to make a final volume of 1.25 L. This can be calculated using the formula: grams of solute = Molarity x volume (in liters) x molar mass of solute.
Q: What is the ionic compound formula for calcium nitrite?
A: The ionic compound formula for Ca(NO2)2 is Ca(NO2)2. It is composed of one calcium ion (Ca2+) and two nitrite ions (NO2-).