Potassium nitrite (KNO2) is a chemical compound commonly used as a food preservative. It is known to inhibit the growth of bacteria and prevent spoilage in meats and other foods.
| IUPAC Name | Potassium Nitrite |
| Molecular Formula | KNO2 |
| CAS Number | 7758-09-0 |
| Synonyms | Nitrous acid, potassium salt; saltpeter (III); nitrous acid, compd. with potassium salt (1:1); E249 |
| InChI | InChI=1S/K.NO2/c;2-1-3/q+1;-1 |
Potassium Nitrite Properties
Potassium Nitrite Formula
The chemical formula of potassium nitrite is KNO2. It represents the composition of the compound in terms of its constituent atoms. The formula of potassium nitrite is used to calculate its molar mass and molecular weight.
Potassium Nitrite Molar Mass
The molar mass of KNO2 is 85.103 g/mol. It is derived from the sum of the atomic masses of potassium (39.10 g/mol), nitrogen (14.01 g/mol), and two oxygen atoms (2 x 16.00 g/mol). The molar mass of KNO2 is essential in determining the amount of substance present in a given mass or volume.
Potassium Nitrite Boiling Point
The boiling point of KNO2 is 320°C (608°F). At this temperature, the compound transforms from a liquid to a gas phase. The boiling point of KNO2 is dependent on various factors, such as pressure and purity.
Potassium Nitrite Melting Point
The melting point of KNO2 is 441°C (826°F). At this temperature, the solid compound transforms to a liquid phase. The melting point of KNO2 is a crucial parameter in determining its suitability for various applications, such as in food preservation and medicine.
Potassium Nitrite Density g/mL
The density of KNO2 is 1.915 g/mL at room temperature. The density of a substance is defined as the mass of the substance per unit volume. The density of KNO2 plays a significant role in determining its physical properties, such as its solubility and chemical reactivity.
Potassium Nitrite Molecular Weight
The molecular weight of KNO2 is 85.103 g/mol. It is a crucial parameter in determining the stoichiometry of a reaction involving KNO2. The molecular weight of KNO2 is also used to determine its physical and chemical properties.
Potassium Nitrite Structure
KNO2 has a molecular formula of KNO2. It has an ionic structure, with potassium cations (K+) and nitrite anions (NO2-). The nitrite ion has a bent molecular geometry, with a bond angle of approximately 115°. The structure of KNO2 is critical in determining its chemical properties, such as its solubility and reactivity.
Potassium Nitrite Solubility
KNO2 is highly soluble in water, with a solubility of approximately 710 g/L at 20°C. The solubility of KNO2 is dependent on various factors such as temperature, pressure, and the presence of other substances. The solubility of KNO2 is a crucial parameter in determining its suitability for various applications, such as in food preservation and medicine.
| Appearance | White to yellowish crystalline solid |
| Specific Gravity | 1.915 |
| Color | Colorless to white |
| Odor | Odorless |
| Molar Mass | 85.103 g/mol |
| Density | 1.915 g/mL |
| Melting Point | 441°C (826°F) |
| Boiling Point | 320°C (608°F) |
| Flash Point | Not applicable |
| Water Solubility | Highly soluble (710 g/L at 20°C) |
| Solubility | Soluble in ethanol, slightly soluble in ammonia |
| Vapor Pressure | 0.0038 mmHg at 25°C |
| Vapor Density | 2.96 (air = 1) |
| pKa | 3.35 |
| pH | 5-8 (5% solution) |
Potassium Nitrite Safety and Hazards
KNO2 can be hazardous if handled improperly. It is harmful if ingested or inhaled and may cause irritation to the eyes, skin, and respiratory system. Prolonged or repeated exposure to KNO2 can cause methemoglobinemia, a condition that reduces the oxygen-carrying capacity of the blood. KNO2 is also a strong oxidizing agent and may react violently with combustible materials, causing fire or explosion. Proper safety measures, such as the use of protective equipment, adequate ventilation, and safe storage, should be followed when handling KNO2. In case of ingestion or inhalation, seek immediate medical attention.
| Hazard Symbols | Xn |
| Safety Description | S22, S24/25 |
| UN IDs | UN 1488 |
| HS Code | 2834.29.10 |
| Hazard Class | 5.1 |
| Packing Group | III |
| Toxicity | Harmful if ingested or inhaled, may cause methemoglobinemia |
Potassium Nitrite Synthesis Methods
Potassium hydroxide (KOH) reacts with nitrous acid (HNO2) to synthesize KNO2. The reaction produces KNO2 and water (H2O) as byproducts. The industry commonly utilizes this method to manufacture large quantities of KNO2.
The equation for the reaction is:
2 KOH + HNO2 → KNO2 + 2 H2O
Another method to synthesize KNO2 involves reacting potassium carbonate (K2CO3) with nitric oxide (NO). The reaction produces KNO2, carbon dioxide (CO2), and nitrogen (N2) as byproducts. Obtaining nitric oxide is difficult and expensive, which makes this method less frequently used.
The equation for the reaction is:
2 K2CO3 + 2 NO → 2 KNO2 + 2 CO2 + N2
One can obtain KNO2 by oxidizing KNO3 using a reducing agent such as SO2 or FeSO4.
The reaction produces KNO2, water, and the reduced form of the reducing agent as byproducts. Scientists less frequently employ this method and typically reserve it for small-scale laboratory synthesis.
The equation for the reaction with sulfur dioxide is:
2 KNO3 + 3 SO2 + H2O → 2 KNO2 + 3 H2SO4
Potassium Nitrite Uses
KNO2 has several industrial and laboratory applications due to its chemical properties. Some of the common uses of KNO2 are:
- Food Preservation: Used as a preservative in cured meats to prevent the growth of harmful bacteria and prolong their shelf life.
- Chemical Industry: Used as an intermediate in the production of several chemicals, such as nitrous acid, diazonium compounds, and organic nitrites.
- Agriculture: Used as a fertilizer and soil conditioner due to its high solubility in water and ability to release nitrogen.
- Laboratory Reagent: Used as a reagent in several laboratory applications, such as the detection of primary amines and the preparation of diazonium salts.
- Medicinal Use: Used in the treatment of cyanide poisoning as it reacts with cyanide ions to form non-toxic cyanmethemoglobin.
- Photography: Used as an additive in photographic developers to improve the quality and clarity of the developed images.
- Glass Industry: Used in the glass industry as a decolorizing agent to remove unwanted coloration from glass products.
Questions:
What is potassium nitrite?
A: KNO2 is an inorganic compound that is commonly used in various industrial and laboratory applications.
Q: What is the formula for potassium nitrite?
A: The chemical formula for potassium nitrite is KNO2.
Q: Which salt is produced when NH4OH reacts with HNO3? KNO2, NaNO3, NH4NO3, or NH4NO2?
A: When NH4OH reacts with HNO3, the salt produced is NH4NO3.
Q: Is KNO2 an acid or base?
A: KNO2 is a basic compound.
Q: What is the name of the compound with the formula KNO2?
A: The name of the compound with the formula KNO2 is potassium nitrite.
Q: Is KNO2 a weak base?
A: KNO2 is considered a weak base.
Q: Is KNO2 acidic or basic?
A: KNO2 is basic in nature and can act as a mild reducing agent.