Potassium sulfite (K2SO3) is a chemical compound made up of potassium, sulfur, and oxygen. It is commonly used as a preservative in the food industry to prevent discoloration and spoilage.
| IUPAC Name | Potassium sulfite |
| Molecular Formula | K2SO3 |
| CAS Number | 10117-38-1 |
| Synonyms | Dipotassium sulfite; Sulfurous acid dipotassium salt; Potassium sulfonate; Potassium sulfur oxide |
| InChI | InChI=1S/2K.H2O3S/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2 |
Potassium Sulfite
Potassium Sulfite Formula
Potassium sulfite has the chemical formula K2SO3, which indicates that it contains two atoms of potassium, one atom of sulfur, and three atoms of oxygen. The compound is formed by the reaction between potassium hydroxide (KOH) and sulfur dioxide (SO2). Potassium sulfite is an ionic compound, meaning that it is composed of positively charged potassium ions and negatively charged sulfite ions. The formula for sulfite ion is SO32-.
Potassium Sulfite Molar Mass
The molar mass of K2SO3 is 158.26 g/mol. This is calculated by adding up the atomic masses of each element in the formula (2 x atomic mass of K) + atomic mass of S + (3 x atomic mass of O). The molar mass of a compound is important because it helps in calculating the amount of the compound needed for a given reaction or in determining the concentration of a solution.
Potassium Sulfite Boiling Point
K2SO3 does not have a specific boiling point because it decomposes before it reaches its boiling point. However, when heated, K2SO3 undergoes thermal decomposition to form potassium sulfate (K2SO4) and sulfur dioxide (SO2). The decomposition temperature is around 390°C.
Potassium Sulfite Melting Point
The melting point of K2SO3 is around 350°C. At this temperature, the solid compound converts into a liquid. However, as the temperature increases, K2SO3 decomposes, as mentioned earlier.
Potassium Sulfite Density g/mL
The density of K2SO3 is 2.44 g/mL at room temperature. Density is defined as the mass of a substance per unit volume. The high density of K2SO3 indicates that it is a relatively heavy compound. This property is important in determining the physical properties of the compound, such as its solubility and reactivity.
Potassium Sulfite Molecular Weight
The molecular weight of K2SO3 is 158.26 g/mol. This value represents the average mass of one molecule of the compound. Molecular weight is important in calculating the amount of a substance in a given volume or mass, which is useful in chemical reactions and laboratory experiments.
Potassium Sulfite Structure
K2SO3 has a crystalline structure, which means that its atoms are arranged in a repeating pattern. The compound has a trigonal planar geometry, with the sulfur atom at the center and the three oxygen atoms arranged symmetrically around it. The potassium ions are located outside this structure, balancing the negative charge of the sulfite ions.
Potassium Sulfite Solubility
K2SO3 is highly soluble in water. At room temperature, it can dissolve in water to form a clear, colorless solution. The solubility of K2SO3 is due to its ionic nature, which allows it to dissociate into its constituent ions in water. The solubility of K2SO3 is also affected by temperature, with solubility increasing as the temperature increases.
| Appearance | White crystalline powder |
| Specific Gravity | 2.44 |
| Color | Colorless |
| Odor | Odorless |
| Molar Mass | 158.26 g/mol |
| Density | 2.44 g/mL |
| Melting Point | 350°C |
| Boiling Point | Decomposes at 390°C |
| Flash Point | Not applicable |
| Water Solubility | Highly soluble in water |
| Solubility | Soluble in ethanol and glycerol |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | 10.3 (for sulfurous acid) |
| pH | ~9 (for a 0.1 M solution) |
Potassium Sulfite Safety and Hazards
K2SO3 is relatively safe to handle and use if proper precautions are taken. However, it can pose hazards if not handled with care. The compound can cause irritation to the skin, eyes, and respiratory system if it comes into contact with these parts of the body. K2SO3 can also cause gastrointestinal problems if ingested. Additionally, the compound is a potential fire and explosion hazard when exposed to heat or flames. Therefore, appropriate safety measures should be taken when working with K2SO3, such as wearing protective equipment and storing the compound away from heat and sources of ignition.
| Hazard Symbols | Skull and crossbones |
| Safety Description | Toxic, harmful if ingested, skin and eye irritant |
| UN IDs | UN 2697 |
| HS Code | 283210 |
| Hazard Class | 6.1 (Toxic substances) |
| Packing Group | II (Medium danger) |
| Toxicity | Oral (LD50): 345 mg/kg (rat) |
Potassium Sulfite Synthesis Methods
K2SO3 can be synthesized by different methods, including the reaction of potassium hydroxide with sulfur dioxide or sulfur, the reaction of potassium carbonate with sulfur dioxide, and the reaction of potassium bisulfite with potassium hydroxide.
In the first method, a solution of potassium hydroxide is reacted with sulfur dioxide gas in the presence of water to form K2SO3. In the second method, a mixture of potassium carbonate and sulfur dioxide is heated at high temperatures to produce K2SO3. The third method involves mixing potassium bisulfite with potassium hydroxide to produce K2SO3 and water.
Another common method of synthesizing K2SO3 is the reaction of sulfur dioxide with a potassium salt, such as potassium chloride, in the presence of reducing agents like sodium hydrosulfite or iron(II) sulfate. This method is often used in industrial settings to produce large quantities of K2SO3.
Potassium Sulfite Uses
K2SO3 has several applications across different industries due to its chemical properties. Here are some common uses of K2SO3:
- Food and beverage industry: Used as a food preservative to prevent spoilage and discoloration in foods such as wine, dried fruits, and shrimp.
- Photography: Used as a photographic fixing agent to prevent further development of the film and make the image permanent.
- Water treatment: Used as a reducing agent to remove chlorine from water and to treat wastewater.
- Paper industry: Used as a bleaching agent to remove impurities and whiten pulp in the paper manufacturing process.
- Textile industry: Used as a reducing agent to remove excess dye from fabrics and to bleach textiles.
- Chemical industry: Used as a reducing agent in chemical reactions to convert oxidizing agents into reducing agents.
- Medicinal industry: Used in some medical treatments to prevent or relieve symptoms of certain conditions.
Questions:
Q: What is the formula for potassium sulfite?
A: The formula for potassium sulfite is K2SO3.
Q: Is potassium sulfate a sulfite?
A: No, potassium sulfate is not a sulfite. It is a salt composed of potassium, sulfur, and oxygen with the chemical formula K2SO4.
Q: Which salt is produced when H2SO4 reacts with NaOH? K2SO3, Na2SO4, Na2SO3, K2SO4
A: When H2SO4 reacts with NaOH, the salt produced is Na2SO4.
Q: How many SO32- ions are contained in 99.6 mg of Na2SO3?
The molar mass of Na2SO3 is 126.05 g/mol. A: To calculate the number of SO32- ions, we first need to find the number of moles of Na2SO3: 99.6 mg / 126.05 g/mol = 0.000789 mol. Since Na2SO3 contains two SO32- ions per molecule, the number of SO32- ions in 0.000789 mol of Na2SO3 is 0.000789 mol x 2 = 0.00158 mol. Therefore, there are 0.00158 mol x 6.022 x 10^23 ions/mol = 9.52 x 10^20 SO32- ions in 99.6 mg of Na2SO3.
Q: How many sodium ions are contained in 99.6 mg of Na2SO3? The molar mass of Na2SO3 is 126.05 g/mol.
A: To calculate the number of sodium ions, we first need to find the number of moles of Na2SO3: 99.6 mg / 126.05 g/mol = 0.000789 mol. Since each molecule of Na2SO3 contains two sodium ions, the number of sodium ions in 0.000789 mol of Na2SO3 is 0.000789 mol x 2 = 0.00158 mol. Therefore, there are 0.00158 mol x 6.022 x 10^23 ions/mol = 9.52 x 10^20 sodium ions in 99.6 mg of Na2SO3.
Q: What is the chemical name for Na2SO3?
A: The chemical name for Na2SO3 is sodium sulfite.
Q: What is the name of the compound with the formula Na2SO3?
A: The name of the compound with the formula Na2SO3 is sodium sulfite.