Chlordane (organochlorine insecticide) Chlordane Chlordane is a persistent organochlorine insecticide formerly used for seed treatment, wood preservation and termite control; now widely restricted because of persistence, bioaccum…
Chloric acid (HClO3): properties, preparation and safety Chloric acid Chloric acid (HClO3) is the oxoacid of chlorine in oxidation state +5, known mainly in aqueous solution. It is a strong oxidizing acid and the parent of chlorate salts; it requires…
Chloride (Cl−): properties, occurrence, biological and industrial roles Chloride Chloride is the negatively charged ion of chlorine (Cl−). It is abundant in nature, essential for life, present in common salts, used industrially, and monitored in medicine and th…
Chlorine: properties, history, production and uses Chlorine Chlorine is a reactive, greenish‑yellow halogen gas (Cl) used widely in water treatment, industry and chemistry; it has two stable isotopes and is produced mainly by electrolysis o…
Chlorine dioxide (ClO2): properties, production, uses, and safety Chlorine dioxide Chlorine dioxide (ClO2) is a yellow‑green, highly reactive gas used as a disinfectant and bleaching agent. It is a strong oxidizer with distinct chemistry, widespread industrial us…
Chlorine monofluoride (ClF) Chlorine monofluoride Chlorine monofluoride (ClF) is the simplest interhalogen compound of chlorine and fluorine. A reactive, polar diatomic species used as a fluorinating and oxidizing reagent; highly…
Chlorite (ClO2−): chemistry, preparation, uses and safety Chlorite Chlorite is the ClO2− oxyanion with chlorine in oxidation state +3. Common as salts (notably sodium chlorite), it is an oxidizer used in bleaching and disinfection and requires car…
Chloroacetic acid (monochloroacetic acid) Chloroacetic acid A simple organochloride acid (C2H3ClO2) used as an intermediate in industrial chemistry; corrosive and toxic, with applications in dyes, polymers and pharmaceuticals.
Chlorofluorocarbon (CFC): chemistry, uses, environmental impact and alternatives Chlorofluorocarbon Chlorofluorocarbons (CFCs) are halogenated compounds once widely used as refrigerants, solvents and propellants. This article explains their chemistry, history, environmental harm…
Chloroform (trichloromethane): properties, uses, history and safety Chloroform Comprehensive overview of chloroform (trichloromethane): chemical identity, physical characteristics, historical role as an anesthetic, industrial uses including PTFE production, a…
Chlorous acid (HClO2): properties, preparation, and uses Chlorous acid Chlorous acid (HClO2) is an unstable oxyacid of chlorine with the chlorite ion as its conjugate base; it exists mainly as transient solutions and intermediates and is a strong oxid…
Choking agent (pulmonary chemical weapon) Choking agent Choking agents are pulmonary chemical agents that damage the lungs and cause fluid accumulation and breathing failure. Examples include chlorine and phosgene; they have industrial…
Cholesterol: function, structure, health implications, and management Cholesterol An overview of cholesterol: its chemical nature, biological roles, transport and synthesis, clinical significance and common approaches to diagnosis and management.
Choline: roles, dietary sources, health effects, and safety Choline Choline is an essential nutrient involved in neurotransmission, membrane structure, methyl-group metabolism, liver function and fetal development. This article summarizes functions…
Chondroitin sulfate: structure, biological role, and uses Chondroitin sulfate Chondroitin sulfate is a sulfated glycosaminoglycan found in connective tissues, especially cartilage. This article explains its structure, biological functions, natural sources, c…
Chromate (CrO4^2−): properties, reactions, uses and safety Chromate Chromate (CrO4^2−) is a chromium(VI) oxyanion used in pigments, corrosion inhibitors and oxidation chemistry; it is strongly oxidizing in acid and poses significant health and envi…
Chromatography: principles, types, and applications Chromatography Chromatography is a laboratory technique for separating components of a mixture based on differential distribution between a mobile and a stationary phase. Common methods include p…
Chrome alum (potassium chromium sulfate) Chrome alum Chrome alum (KCr(SO4)2·12H2O) is a violet, crystalline alum of chromium(III) used historically as a mordant and for laboratory demonstrations; it has distinctive coordination chemi…
Chromic acid: properties, preparation, uses and hazards Chromic acid Chromic acid refers to several related chromium(VI) oxidizing species produced from chromates or chromium(VI) oxide. It is a powerful oxidant with important laboratory uses and sig…
Chromium — properties, chemistry, uses, and safety Chromium Chromium (Cr, atomic number 24) is a silvery transition metal used in alloys, plating and pigments. This article summarizes its properties, occurrence, compounds, major uses and sa…
Chromium(II) chloride: properties, synthesis, and laboratory handling Chromium(II) chloride Chromium(II) chloride (CrCl2): properties, synthesis routes, reactivity as a strong reducing agent, and laboratory handling and storage precautions to prevent oxidation and contami…
Chromium(II) oxide (CrO) Chromium(II) oxide Chromium(II) oxide, CrO, is the monoxide of chromium. It is a less-stable chromium oxide that acts as a reducing agent, readily oxidizes to Cr2O3, and is encountered mainly in spec…
Chromium(III) chloride (CrCl3) Chromium(III) chloride Inorganic salt chromium(III) chloride (CrCl3): green hydrated and purple anhydrous forms, octahedral Cr3+, common laboratory reagent and synthetic precursor; less toxic than hexava…
Chromium(III) oxide (Cr2O3) Chromium(III) oxide Chromium(III) oxide, Cr2O3, is a stable dark green inorganic oxide of chromium(III). It is used as a pigment, in metal production, and as the protective passive layer on stainless…
Chromium(III) sulfate Chromium(III) sulfate (Cr2(SO4)3) is a water‑soluble chromium salt used chiefly in leather tanning; it occurs in several hydrated forms, is prepared from chromium or chromates, and…
Chromium(IV) oxide (chromium dioxide, CrO2) Chromium(IV) oxide Chromium(IV) oxide (CrO2) is a black, crystalline inorganic compound known for its ferromagnetic properties and historical use as the magnetic pigment in audio and video tapes.
Chromium(VI) oxide (chromium trioxide) Chromium(VI) oxide Chromium(VI) oxide (CrO3) is a red crystalline, highly oxidizing inorganic solid used historically in plating, glass cleaning and organic oxidations; it is highly toxic, corrosive…
Chromophore: the light‑absorbing part of a molecule Chromophore A chromophore is the region of a molecule that absorbs specific wavelengths of light and produces colour; it underlies pigments, biological photoreceptors, dyes and many optical ap…
Chromyl chloride (CrO2Cl2): properties, preparation, uses, and safety Chromyl chloride Chromyl chloride (CrO2Cl2) is a red, volatile chromium(VI) oxychloride used as an oxidizing reagent and for the qualitative chromyl chloride test; it is highly toxic and corrosive.
Cinnabar: the red mercury sulfide mineral and its uses Cinnabar Cinnabar (HgS) is the principal ore of mercury, known for its bright red color and use as vermilion pigment; it has two crystal forms, a long mining history, and significant toxici…
Citric acid: properties, biological role, uses and history Citric acid Citric acid is a naturally occurring weak organic acid found in citrus fruits. This article summarizes its chemistry, role in metabolism, industrial production, applications, histo…
Clandestine chemistry: illegal synthesis, risks, and social impacts Clandestine chemistry Clandestine chemistry refers to secret, unregulated chemical production—most often illicit drug synthesis—carrying acute safety, environmental and legal hazards and requiring speci…
Cofactor (biochemistry): nonprotein components essential for enzyme activity Co-factor A cofactor is a nonprotein chemical element or compound—metal ion or organic coenzyme—required for many proteins, especially enzymes, to catalyze reactions or maintain structural f…
Cobalt: Transition Metal Properties, Industrial Uses, and Biological Importance Cobalt Cobalt (Co): a ferromagnetic transition metal — properties, chemistry and occurrence; major industrial uses (batteries, superalloys, catalysts), global production, and its biologic…
Cobalt oxide Inorganic oxides of cobalt, chiefly cobalt(II) oxide (CoO) and cobalt(II,III) oxide (Co3O4). Overview of structures, preparation, properties, applications in ceramics, catalysis an…
Cobalt(II,III) oxide (Co3O4): properties, structure and applications Cobalt(II,III) oxide Cobalt(II,III) oxide (Co3O4) is a mixed‑valence cobalt oxide with a spinel structure. This black crystalline solid is used as a catalyst, pigment precursor and in battery and senso…
Cobalt(II) chloride Cobalt(II) chloride (CoCl2) is a hygroscopic inorganic salt of cobalt in the +2 oxidation state, known for its reversible color change with hydration and its use as a humidity indi…
Cobalt(II) fluoride (CoF2) — properties, preparation and uses Cobalt(II) fluoride Cobalt(II) fluoride (CoF2) is a divalent cobalt salt used in inorganic synthesis and materials research. It exists as anhydrous and hydrated solids and requires careful handling be…
Cobalt(II) hydroxide Cobalt(II) hydroxide (Co(OH)2) is an inorganic compound that appears as blue or reddish solids, used as a precursor to cobalt oxides, pigments, catalysts and some electrochemical m…
Cobalt(II) oxide (CoO) Cobalt(II) oxide Cobalt(II) oxide, CoO, is the binary oxide of cobalt in the +2 state. It is a transition-metal oxide used as a pigment precursor, catalyst component and material for ceramics and b…
Cobalt(II) sulfate (cobaltous sulfate) Cobalt(II) sulfate Cobalt(II) sulfate (CoSO4) is a water‑soluble cobalt(II) salt found as hydrated crystals. It serves as a precursor for pigments, electroplating baths, catalysts, and veterinary mic…
Cobalt(III) fluoride (CoF3) Cobalt(III) fluoride Cobalt(III) fluoride (CoF3) is a brown, crystalline inorganic compound used as a fluorinating oxidant. It contains cobalt in the +3 state and reacts violently with moisture to prod…
Cobalt(III) oxide (Co2O3) Cobalt(III) oxide Cobalt(III) oxide (Co2O3) is an inorganic cobalt oxide containing cobalt in the +3 oxidation state. It is less common and less stable than other cobalt oxides and is used mainly as…
Coenzyme A Coenzyme A (CoA) is an essential metabolic cofactor that carries acyl groups, links major pathways such as the Krebs cycle and fatty acid metabolism, and is derived from vitamin B5…
Cohesion (chemistry) Cohesion in chemistry is the intermolecular attraction between like molecules that holds a substance together and gives rise to phenomena such as surface tension, droplets, and cap…
Cold (temperature, perception and effects) Cold An encyclopedic overview of cold: its physical meaning, perception, measurement scales, effects on materials and life, and technologies that control low temperatures.
Colloid: Definition, Types, Properties, and Applications Colloid A colloid is a mixture in which tiny particles of one substance are dispersed throughout another. This article explains characteristics, common types, history, uses, and distinguis…
Colorimeter: Principles, Components, History and Practical Uses Colorimeter A colorimeter measures light absorbance or reflectance to quantify colour and estimate concentration. This article covers principles (Beer–Lambert), components, operation, calibrat…
