Potassium phosphate (K3PO4) is a compound that contains the elements potassium and phosphorus. It is commonly used as a food additive and fertilizer due to its high solubility and ability to provide essential nutrients for plant growth.
| IUPAC name | Potassium phosphate |
| Molecular formula | K3PO4 |
| CAS number | 7778-53-2 |
| Synonyms | Tripotassium phosphate, Potassium orthophosphate, Potassium tertiary phosphate, Tripotassium monophosphate, Potassium phosphate tribasic |
| InChI | InChI=1S/3K.H3O4P/c;;;1-5(2,3)4/h;;;(H3,1,2,3,4)/q3*+1;/p-3 |
Potassium Phosphate Properties
Potassium Phosphate Formula
The chemical formula of potassium phosphate is K3PO4. It indicates that the compound contains three K+ ions and one PO43- ion in each formula unit. The formula of potassium phosphate is useful in determining the stoichiometry of reactions involving the compound, as well as in identifying the amount of each element present in a given mass of the compound.
Potassium Phosphate Molar Mass
The molar mass of K3PO4 is 212.27 g/mol. It is calculated by adding the atomic masses of potassium, phosphorus, and oxygen to the compound. The molar mass is an important parameter in determining the amount of substance present in a given mass of the compound. It is also useful in calculating the stoichiometry of reactions involving K3PO4.
Potassium Phosphate Boiling Point
The boiling point of K3PO4 is 1,660°C. This high boiling point is due to the strong ionic bonds between the K+ ions and PO43- ions in the compound. It is also an indication of the stability of the compound at high temperatures. The boiling point of K3PO4 is useful in various industrial applications, such as in the production of ceramics and glass.
Potassium Phosphate Melting Point
The melting point of K3PO4 is 1,340°C. It is the temperature at which the solid compound changes to a liquid state. The high melting point of K3PO4 is due to the ionic nature of the compound, which requires a high amount of energy to overcome the attractive forces between the ions. The melting point of K3PO4 is useful in determining its suitability for various applications, such as in the production of fertilizers and food additives.
Potassium Phosphate Density g/mL
The density of K3PO4 is 2.564 g/mL at room temperature. The high density of the compound is due to the presence of three K+ ions and one PO43- ion in each formula unit. The density of K3PO4 is useful in determining its solubility and its behavior in various industrial processes, such as in the production of fertilizers and food additives.
Potassium Phosphate Molecular Weight
The molecular weight of K3PO4 is 212.27 g/mol. It is the sum of the atomic weights of all the atoms in the compound. The molecular weight is useful in calculating the amount of substance present in a given mass of the compound, as well as in determining the stoichiometry of reactions involving K3PO4.
Potassium Phosphate Structure
K3PO4 has an orthorhombic crystal structure. It consists of an array of PO4 tetrahedra, with each phosphate ion sharing two oxygen atoms with neighboring phosphate ions. The potassium ions are located between the phosphate tetrahedra, surrounded by oxygen atoms. The structure of K3PO4 is useful in understanding its properties, such as its solubility and thermal stability.
| Appearance | White crystalline powder |
| Specific gravity | 2.564 g/mL |
| Color | White |
| Odor | Odorless |
| Molar mass | 212.27 g/mol |
| Density | 2.564 g/mL |
| Melting point | 1,340°C |
| Boiling point | 1,660°C |
| Flash point | Not applicable |
| Water solubility | 100 g/L (20°C) |
| Solubility | Soluble in ethanol and acetone, insoluble in ether |
| Vapour pressure | Negligible |
| Vapour density | Not applicable |
| pKa | pKa1 = 2.16, pKa2 = 7.21, pKa3 = 12.32 |
| pH | pH of a 1% solution is 11.5 |
Potassium Phosphate Safety and Hazards
K3PO4 is generally considered safe for use when handled properly. However, like any chemical, it can pose hazards if mishandled or ingested in large amounts. The compound is classified as a skin, eye, and respiratory irritant and can cause severe burns or respiratory distress if inhaled or ingested in high concentrations. It is also incompatible with acids and oxidizing agents and can cause fire or explosion if exposed to these materials. Therefore, it is important to handle K3PO4 with caution, wear appropriate protective equipment, and store it in a cool, dry, and well-ventilated area away from incompatible substances.
| Hazard symbols | Xi (Irritant) |
| Safety description | Avoid contact with skin and eyes. |
| UN IDs | UN 2833 (for anhydrous), UN 2423 (for trihydrate) |
| HS code | 28352400 |
| Hazard class | 6.1 (toxic) |
| Packing group | III |
| Toxicity | LD50 (oral, rat): 2,340 mg/kg; LC50 (inhalation, rat): 50 mg/L |
Potassium Phosphate (K3PO4) Synthesis Methods
Several methods exist to synthesize K3PO4, including reacting phosphoric acid (H3PO4) with potassium hydroxide (KOH) or thermally decomposing KH2PO4.
One method involves reacting equimolar amounts of KOH and H3PO4 in water at a temperature of around 60-80°C. The procedure involves evaporating the resulting mixture and heating the solid residue to about 300°C to produce K3PO4.
Another method involves reacting KH2PO4 with KOH at a high temperature (above 400°C) to yield K3PO4 and water. A specialized furnace can carry out this process known as thermal decomposition.
The reaction of phosphoric acid with potassium carbonate (K2CO3) and the reaction of potassium oxide (K2O) with phosphorus pentoxide (P2O5) are additional methods for producing K3PO4.
Potassium Phosphate Uses
K3PO4 has several practical uses across a range of industries, including:
- Fertilizer: Commonly used as a fertilizer due to its high phosphorus content. Farmers often add it to the soil to provide essential nutrients to plants.
- Food industry: Used as a food additive to regulate acidity levels, prevent discoloration, and enhance texture.
- Buffering agent: Various laboratory applications use it as an effective buffering agent, including pH calibration buffer solutions and biological research.
- Detergents: Used in the production of detergents and cleaning products due to its ability to soften water and prevent the buildup of mineral deposits.
- Medicine: Used as a dietary supplement to treat certain medical conditions, such as low phosphate levels in the blood.
- Water treatment: Used in water treatment to prevent the formation of scale and corrosion in pipes and equipment.
- Fire retardant: Used as a fire retardant in various materials, including textiles and plastics, due to its ability to release water vapor and prevent the spread of flames.
Questions:
Q: Is potassium phosphate soluble in water?
A: Yes, K3PO4 is soluble in water.
Q: How many potassium ions are needed to bond with a phosphate ion?
A: Three potassium ions are needed to bond with one phosphate ion, forming K3PO4.
Q: What precipitate forms when aqueous solutions of calcium bromide and potassium phosphate are mixed?
A: When aqueous solutions of calcium bromide and K3PO4 are mixed, a precipitate of calcium phosphate (Ca3(PO4)2) forms.
Q: Is k3po4 soluble in water?
A: Yes, K3PO4 is soluble in water.
Q: Is k3po4 soluble?
A: Yes, K3PO4 is soluble in water.
Q: What products result from mixing aqueous solutions of Ni(C2H3O2)2 (aq) and K3PO4 (aq)?
A: When aqueous solutions of Ni(C2H3O2)2 and K3PO4 are mixed, a precipitate of nickel(II) phosphate (Ni3(PO4)2) forms, along with aqueous solutions of potassium acetate (KCH3COO) and acetic acid (CH3COOH).
Q: Which element increases its oxidation number in this reaction? 3KOH + H3PO4 → K3PO4 + 3H2O
A: The element phosphorus increases its oxidation number from +5 in H3PO4 to +5 in K3PO4.
Q: What is K3PO4?
A: K3PO4 is the chemical formula for potassium phosphate, a compound that is used in various applications, such as fertilizers, food additives, and cleaning products.