Visually, potassium nitrate (KNO3) and potassium chloride (KCl) may be difficult to differentiate because they both appear as colorless or white crystals. However, the two compounds may be distinguished from each other by conducting chemical processes and laboratory tests to check the physical properties.
A simple way of differentiating potassium chloride from potassium nitrate is by capitalizing on their physical properties. Potassium chloride has a significantly higher melting point at 770 degrees Celsius compared to potassium nitrate at only 334 degrees Celsius, and this property may be identified using melting point laboratory equipment, such as the Kofler hot bench. In a similar fashion, identification of the compound may be done by comparing boiling points and water solubility.
The compounds may also be identified based on their crystalline structure. Under the microscope, potassium chloride appears as elongated or prismatic crystals, while potassium nitrate have more of a rhombic or trigonal structure.
Potassium nitrate is a natural source of nitrogen, and it is useful in fertilizers and pyrotechnics. Potassium chloride, on the other hand, is similar to table salt and is used in the fields of food processing and medicine. One of the sources of confusion is that both compounds allude to the term "potash," with potassium chloride commonly known as "muriate of potash" and potassium nitrate is known as "nitrate of potash."