Calcium nitrate, also known as Norwegian saltpeter, is an ionic salt that is made up of calcium cations and nitrate anions. The chemical formula of this inorganic compound is Ca(NO3)2. Under standard conditions for temperature and pressure (often abbreviated to STP), calcium nitrate exists as a colorless solid that absorbs the moisture in its environment to form a tetra hydrate. The physical and chemical properties of calcium nitrate are detailed in this article along with its uses.
Properties of Calcium Nitrate
Physical Properties of Calcium Nitrate
- The molar mass of anhydrous calcium nitrate is 164.088 grams per mole.
- The molar mass of the tetra hydrate form of this compound is equal to 236.15 grams per mole.
- Anhydrous calcium nitrate has a density of 2.504 grams per cubic centimetre.
- The density of the tetra hydrate form of Ca(NO3)2 is equal to 1.896 grams per cubic centimetre.
- The melting point of anhydrous calcium nitrate is equal to 561 degrees Celsius or 834 Kelvin. The boiling point of the anhydrous form is not defined since the compound decomposes at high temperatures.
- Ca(NO3)2.4H2O has a melting point of 42.7 degrees Celsius or 316 Kelvin. The boiling point of the tetra hydrate of calcium nitrate is roughly equal to 132 degrees Celsius or 405 Kelvin.
Chemical Properties of Calcium Nitrate
Calcium nitrate is quite soluble in water. The anhydrous form of this compound is slightly more soluble in water than the dehydrate. As is the case with most other compounds, the solubility of calcium nitrate in water increases as the temperature increases. For example, at a temperature of 20 degrees Celsius, the solubility of anhydrous calcium nitrate in water is equal to 1212 grams per liter. When the temperature is increased to 40 degrees Celsius, its solubility also increases to 2710 grams per liter.
The solubility of the tetra hydrate of calcium nitrate in water is equal to 1290 grams per liter at a temperature of 20 degrees Celsius. However, at 100 degrees Celsius, the solubility of the tetra hydrate increases to 3630 grams per liter. It can also be noted that calcium nitrate is soluble in ammonia, ethanol, methanol, and some other organic solvents. However, this compound is close to insoluble in nitric acid.
What are the Uses of Calcium Nitrate?
One of the most notable applications of calcium nitrate is as a fertilizer, especially in greenhouse setups and hydroponics setups. Calcium nitrate, in combination with boric acid, can be used to increase fruit retention and fruit yield in some plants. This compound is also used in the treatment of wastewater. Calcium nitrate can be added to wastewater before it is processed in order to control the emission of foul odours. This is because the metabolism of sulfates by the associated bacteria is inhibited by the presence of nitrates.
Another important application of calcium nitrate is in set accelerating concrete admixtures. Here, the calcium ion is employed to speed up the formation of calcium hydroxide (a chemical compound with the formula Ca(OH)2). The nitrate ion also contributes to the setting process by facilitating the formation of iron hydroxide.
For the production of latex, it is not uncommon for calcium nitrate to be employed as a coagulating agent. This application of calcium nitrate is especially important for dipping processes, where a solution containing dissolved Ca(NO3)2 is used as a component of the dipping bath. The dissolution of the tetra hydrate of this compound can be exploited for a cooling effect (since the dissolution of Ca(NO3)2.4H2O is an endothermic process). Thus, this compound is ideal for use in cold packs.