Potassium bicarbonate (KHCO3) serves as a white crystalline salt, widely utilized as a leavening agent in baking, a fire extinguishing agent, and for neutralizing soil acidity in agriculture. Additionally, it acts as a nutritional supplement and plays a role in specific medical treatments.
| IUPAC Name | Potassium hydrogen carbonate |
| Molecular Formula | KHCO3 |
| CAS Number | 298-14-6 |
| Synonyms | Potassium acid carbonate, potassium acid salt, potassium hydrogen carbonate, PCN 0775, E501 |
| InChI | InChI=1S/CH2O3.K/c2-1(3)4;/h(H2,2,3,4);/q;+1/p-1 |
Potassium Bicarbonate Properties
Potassium Bicarbonate Formula
The formula for potassium bicarbonate is KHCO3. This formula indicates that one potassium ion (K+) is combined with one bicarbonate ion (HCO3-) to form one molecule of potassium bicarbonate. The formula is important in chemistry as it provides information about the types and numbers of atoms that make up a molecule.
Potassium Bicarbonate Molar Mass
KHCO3 has a molar mass of 100.115 g/mol. This means that one mole of KHCO3 contains 100.115 grams of the compound. Molar mass is an important property of a compound, as it is used to calculate the amount of a substance needed for a chemical reaction. In addition, molar mass can be used to convert between grams and moles of a substance.
Potassium Bicarbonate Boiling Point
The boiling point of KHCO3 is not well-defined since it decomposes before reaching its boiling point. When heated, KHCO3 decomposes into potassium carbonate, carbon dioxide, and water. Therefore, the decomposition temperature of KHCO3 is used to describe its thermal stability.
Potassium Bicarbonate Melting Point
KHCO3 has a melting point of 292°C. At this temperature, KHCO3 transforms from a solid to a liquid. The melting point of a compound is an important physical property as it determines the conditions under which the compound can be melted and processed.
Potassium Bicarbonate Density g/mL
The density of KHCO3 is 2.17 g/mL. Density is a measure of the amount of mass per unit volume. The high density of KHCO3 makes it a useful compound in applications such as fire extinguishers, where it is used to extinguish Class B fires.
Potassium Bicarbonate Molecular Weight
The molecular weight of KHCO3 is 100.115 g/mol. The molecular weight is the sum of the atomic weights of all atoms in a molecule. This property is important in chemistry as it is used to calculate the amount of a substance needed for a chemical reaction.
Potassium Bicarbonate Structure
KHCO3 has a crystal structure that is similar to that of sodium chloride. The compound is made up of potassium ions (K+) and bicarbonate ions (HCO3-). The potassium ions occupy the positions of the sodium ions in the sodium chloride crystal structure, while the bicarbonate ions occupy the positions of the chloride ions.
| Appearance | White crystalline powder |
| Specific Gravity | 2.17 g/cm³ |
| Color | White |
| Odor | Odorless |
| Molar Mass | 100.115 g/mol |
| Density | 2.17 g/cm³ |
| Melting Point | 292 °C |
| Boiling Point | Decomposes before boiling |
| Flash Point | Not applicable |
| Water Solubility | 25 g/100 mL (20°C) |
| Solubility | Soluble in water |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| pKa | 10.3 (carbonic acid) |
| pH | 8.5 – 9.5 (1% solution) |
Potassium Bicarbonate Safety and Hazards
KHCO3 is generally considered safe when used as directed. However, it can cause skin and eye irritation and should be handled with care. It can also be harmful if ingested in large amounts. Inhalation of the dust may cause respiratory irritation. Additionally, it can react with strong acids to release carbon dioxide gas, which can be hazardous. When using KHCO3, it is important to follow safety procedures and wear appropriate protective equipment. In case of ingestion, seek medical attention immediately. In case of skin or eye contact, wash the affected area thoroughly with water and seek medical attention if irritation persists.
| Hazard Symbols | None |
| Safety Description | Harmful if swallowed, causes skin and eye irritation. Avoid inhalation. |
| UN IDs | UN 2987 |
| HS Code | 2836.30.00 |
| Hazard Class | 8 (Corrosive) |
| Packing Group | III |
| Toxicity | LD50 (rat, oral): 6,400 mg/kg |
Potassium Bicarbonate Synthesis Methods
In the presence of water, carbon dioxide gas reacts with potassium carbonate to synthesize KHCO3.
The reaction occurs as follows:
K2CO3 + CO2 + H2O → 2KHCO3
Another method involves reacting potassium hydroxide with carbon dioxide gas:
KOH + CO2 → KHCO3
The resulting KHCO3 can then be purified by recrystallization from water. The yield of the reaction depends on the purity of the starting materials and the reaction conditions.
To produce KHCO3, one can react potassium chloride with ammonium bicarbonate and then treat the resulting mixture with carbon dioxide gas.
NH4HCO3 + KCl → NH4Cl + KHCO3
KHCO3 + CO2 → K2CO3 + H2O
K2CO3 + CO2 + H2O → 2KHCO3
This method has the advantage of using inexpensive starting materials and does not produce any hazardous byproducts.
Potassium Bicarbonate Uses
KHCO3 has a wide range of uses in various industries and applications. Here are some of the most common uses:
- Food industry: Used as a leavening agent in baked goods, such as cakes, cookies, and bread, to help them rise.
- Agriculture: Used as a fungicide to control fungal diseases in plants, such as powdery mildew.
- Pharmaceuticals: Used in antacids to neutralize stomach acid and treat indigestion and heartburn.
- Fire extinguishers: Used in fire extinguishers as a dry chemical agent to extinguish Class B and Class C fires.
- Laboratory applications: Used in various laboratory applications, such as pH buffering and cell culture.
- Personal care products: Used in toothpaste as a mild abrasive and in deodorants to help control odor.
- Water treatment: Used in water treatment to adjust the pH level and remove heavy metals and other impurities.
Questions:
Q: What is potassium bicarbonate?
A: KHCO3 is a white, odorless powder that is commonly used in various industries, such as food, agriculture, and pharmaceuticals. It has the chemical formula KHCO3 and is a salt that is composed of potassium cation, bicarbonate anion, and water molecules.
Q: Does the bicarbonate in effervescent potassium tablets turn into carbon dioxide?
A: Yes, when effervescent potassium tablets dissolve in water, the bicarbonate in the tablet reacts with the citric acid to release carbon dioxide gas. This reaction produces the characteristic fizzing and bubbling that is associated with effervescent tablets.
Q: What happens after adding potassium bicarbonate to wine?
A: Adding KHCO3 to wine reduces the acidity of the wine by reacting with the excess acid present. Winemakers commonly use this process, known as deacidification, to improve the taste and quality of the wine.
Q: Where to buy potassium bicarbonate?
A: KHCO3 can be purchased from various chemical suppliers, online marketplaces, and agricultural supply stores. It is also commonly available in health food stores and natural food markets.
Q: What is the name of the compound with the formula KHCO3?
A: The compound with the formula KHCO3 is called potassium bicarbonate.
Q: What was done in the experiment to make sure that all KHCO3 was reacted?
A: In the experiment to ensure that all KHCO3 was reacted, excess acid was added to the reaction mixture, and the reaction was continued until no more gas was produced. The absence of gas indicated that all KHCO3 had reacted with the acid.
Q: What happens if you heat KHCO3?
A: When KHCO3 is heated, it decomposes to form potassium carbonate (K2CO3), water, and carbon dioxide gas. This reaction occurs as follows: 2KHCO3 → K2CO3 + H2O + CO2.