Chemistry

Potash: potassium-bearing salts, history, and uses Potash Potash refers to potassium-containing salts and compounds used chiefly as fertilizers and industrial feedstocks; historically derived from wood ashes and now produced by mining and…

Potassium (chemical element K) Potassium Potassium is a soft, highly reactive alkali metal (symbol K, atomic number 19). It occurs only in compounds in nature, is essential for plants and animals, and is widely used in fe…

Potassium aluminium sulfate (potash alum) Potassium aluminium sulfate Potassium aluminium sulfate, KAl(SO4)2, known as potash alum, is a crystalline double sulfate used historically as a mordant and today in water treatment, cosmetics, food, and mino…

Potassium arsenate Inorganic potassium salts of the arsenate oxyanion (K3AsO4, K2HAsO4, KH2AsO4). Tetrahedral arsenate species; historically used in industry and agriculture; highly toxic and strictl…

Potassium arsenite Potassium arsenite (KAsO2) is an inorganic arsenic salt historically used in medicine and industry; it is highly toxic, environmentally mobile, and strictly regulated today.

Potassium bromate (KBrO3): properties, uses, and safety Potassium bromate Potassium bromate (KBrO3) is a white crystalline oxidizing salt used in laboratories and formerly as a flour improver; it poses health and environmental risks and is restricted in…

Potassium bromide (KBr): properties, uses and history Potassium bromide Potassium bromide (KBr) is an inorganic ionic salt used in spectroscopy, photography, and historically as a sedative and anticonvulsant. It is colorless, water-soluble, and handled…

Potassium carbonate (K2CO3): properties, history, and uses Potassium carbonate Potassium carbonate is a white, water‑soluble inorganic salt (K2CO3) used in glassmaking, soap, food processing and laboratory chemistry. It is strongly alkaline and historically k…

Potassium chlorate (KClO3): properties, uses, and safety Potassium chlorate Potassium chlorate (KClO3) is a white crystalline oxidizer used in pyrotechnics, matches, laboratory oxygen production and analytical chemistry. It is a hazardous oxidant that deco…

Potassium chloride (KCl) Potassium chloride Potassium chloride (KCl) is an inorganic salt used widely as a fertilizer, food additive, medical potassium source and laboratory reagent; it is a white, water‑soluble ionic compou…

Potassium chromate (K2CrO4) Potassium chromate Potassium chromate (K2CrO4) is a bright yellow, water-soluble inorganic salt containing chromate anions. It is used as a laboratory reagent and industrial chemical and is a toxic,…

Potassium dichromate: properties, uses, and safety Potassium dichromate Potassium dichromate (K2Cr2O7) is an orange-red crystalline oxidizing salt of hexavalent chromium. It has laboratory and historic industrial uses but is highly toxic and environmen…

Potassium fluoride Potassium fluoride (KF) is an ionic inorganic salt composed of potassium and fluoride ions. It is a water-soluble white crystalline solid used as a fluoride source in chemistry and…

Potassium hydroxide (KOH) — properties, uses, production and safety Potassium hydroxide Potassium hydroxide (KOH) is a strong, hygroscopic base used across industry and laboratories. This article summarizes its composition, properties, production history, common uses…

Potassium hypomanganate A rare, bright-blue potassium salt of the hypomanganate ion (Mn in +5 state). Highly reactive and unstable, it is chiefly observed as a transient species in strongly basic redox ch…

Potassium iodate (KIO3): properties, production, uses, and safety Potassium iodate Potassium iodate (KIO3) is a white, oxidizing salt used to iodize table salt, as a laboratory oxidant, and for iodine prophylaxis; it is chemically distinct from potassium iodide.

Potassium iodide (KI) Potassium iodide Potassium iodide (KI) is an ionic salt of potassium and iodide ions used in medicine, chemistry, and industry as a source of iodide; it has distinctive physical and safety properti…

Potassium manganate (K2MnO4): properties, preparation and uses Potassium manganate Potassium manganate (K2MnO4) is a green, alkaline manganese(VI) compound. It is an intermediate in permanganate manufacture, a laboratory oxidant, and notable for its redox behavio…

Potassium nitrate (saltpeter): properties, history, uses and safety Potassium nitrate Potassium nitrate (KNO3), commonly called saltpeter, is an ionic compound used as a fertilizer, oxidizer in pyrotechnics and propellants, and historically in gunpowder and food cur…

Potassium perchlorate (KClO4) Potassium perchlorate Potassium perchlorate is a white crystalline oxidizing salt used in pyrotechnics, propellants and some industrial processes. It is chemically stable but a strong oxidizer and envir…

Potassium periodate An inorganic potassium salt of periodate, best known as a strong oxidizing agent used in analytical chemistry and organic synthesis.

Potassium permanganate: properties, uses, history, and safety Potassium permanganate An encyclopedic overview of potassium permanganate (KMnO4): chemical characteristics, common applications, preparation and history, hazards and safe handling, with links for furthe…

Potassium sulfate (K2SO4): properties, uses, and history Potassium sulfate Potassium sulfate (K2SO4) is a white crystalline salt supplying potassium and sulfur. Widely used as a chloride-free fertilizer, it also has roles in industry and chemistry and occ…

Potassium sulfide (K2S): properties, preparation, and uses Potassium sulfide Potassium sulfide (K2S) is an inorganic ionic compound containing K+ and S2−. It is a water-sensitive, strongly basic sulfide used as a sulfur source in synthesis and must be handl…

Potassium sulfite Potassium sulfite (K2SO3) is an inorganic potassium salt of the sulfite ion. It is a white, water‑soluble reducing salt used in industrial preservation, water treatment, and chemic…

Praseodymium Praseodymium is a soft, silvery lanthanide metal (atomic number 59) used in alloys, glass coloration, lighting electrodes and specialized optical materials.

Producer gas Producer gas is a low-calorific gaseous fuel made by gasifying solid carbonaceous fuels with air; used historically for engines and heating and still produced for local power and i…

Product (chemistry) A product is the chemical species formed by a reaction. This article defines products, explains types (major products, by-products), stoichiometry, yields, identification, and indu…

Promethium (element 61) — properties, isotopes, history and uses Promethium Promethium (Pm, atomic number 61) is a radioactive lanthanide with no stable isotopes. Produced in nuclear reactions, it has limited industrial uses and is notable for its rarity a…

Propane (C3H8) — properties, uses, production and safety Propane Propane (C3H8) is a three‑carbon alkane commonly used as a fuel. This article summarizes its chemical nature, physical properties, production sources, applications, safety consider…

Propellant: substances and systems that produce thrust or pressure Propellant A propellant is a material that produces gas, pressure, or reactive force to move or eject another object. It includes compressed gases, aerosol vapors, explosives, and rocket fuel…

Propene (propylene): properties, production, uses, and safety Propene Propene (propylene), C3H6, is a three‑carbon alkene used as a key petrochemical feedstock for polymers and industrial chemicals; it is a flammable gas at ambient conditions.

Protactinium: an overview of the radioactive actinide element Protactinium Protactinium (Pa, atomic number 91) is a rare, highly radioactive actinide used primarily in research and geochronology; it is chemically reactive, scarce in nature, and handled un…

Proton: Structure, Properties, and Role in Atomic Nuclei Proton Overview of the proton: its charge, mass, quark substructure, and how proton number defines elements and shapes the composition and stability of atomic nuclei.

Protonation: the addition of a proton to molecules and functional groups Protonation Protonation is the chemical process in which a proton (H+) binds to a molecule, altering structure, reactivity, and charge. It underpins acid–base chemistry, catalysis, biological…

Prussian blue Prussian blue is a deep blue synthetic pigment (ferric ferrocyanide) first produced in early 18th‑century Berlin, widely used in art, printing, textiles, engineering and some medic…

Psilocybin: natural psychedelic compound, effects, history, and uses Psilocybin Psilocybin is a naturally occurring psychedelic found in many mushroom species. It alters perception and cognition, is studied for therapeutic use, and has varied legal status; saf…

Purification: processes, methods, history and practical applications Purification Removal of unwanted substances or contaminants to make a material or environment pure; covers physical, chemical, biological, and ritual approaches and common uses in water, air, a…

Purine: structure and biological role in nucleic acids and metabolism Purine Purines are bicyclic nitrogenous bases found in DNA and RNA. This article explains their chemical structure, biological functions, metabolism, common examples and medical relevance…

Purity Purity describes the absence of unwanted components in a substance and, more broadly, ideals of moral, ritual, or aesthetic cleanliness across cultures and industries.

Pyrimidine Pyrimidine is a six-membered aromatic heterocycle with two nitrogen atoms; its derivatives include the DNA/RNA bases cytosine, thymine and uracil and many biologically important co…

Pyrolysis: thermal decomposition of carbon-containing materials Pyrolysis Pyrolysis is the thermal decomposition of carbon-containing materials in low-oxygen conditions, producing char, liquids and gases; used for charcoal, bio-oil, waste-to-energy and c…

Pyruvic acid: structure, metabolism, and biological roles Pyruvic acid Pyruvic acid (pyruvate) is the simplest keto acid and a central metabolic intermediate. This article explains its chemistry, formation by glycolysis, main biochemical fates, and bi…

Qualitative analysis: identification of chemical substances Qualitative analysis Qualitative analysis determines which chemical species are present in a sample using chemical reactions, color changes, precipitations and instrumental identification; distinct fro…

Quantitative analysis (chemistry) Quantitative analysis determines how much of one or more chemical species is present in a sample, using classical and instrumental methods with calibration, validation and attentio…

Radioactive decay Radioactive decay is the spontaneous change of unstable atomic nuclei that emits particles or photons. It shapes nuclear chemistry, enables medical and dating technologies, and req…

Radiogenic (radiogenic nuclides and isotopes) Radiogenic Radiogenic describes atoms produced by radioactive decay. This article explains how radiogenic nuclides form, common examples, uses in dating and geochemistry, measurement methods,…

Radionuclide A radionuclide is a radioactive isotope of an element that emits ionizing radiation. Found in nature and made artificially, radionuclides have diverse uses in medicine, industry, r…