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Chemical Chameleon
The chemical chameleon is a redox reaction, well known from classroom demonstrations, that exploits the dramatic color changes associated with the various oxidation states of manganese. Oxidation states and the Chemical Chameleon Science and Maths Society Glauber reported the first description of the production of when he noted ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Chameleon Redox Reaction (permanganate)
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent Chemical element, elements by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances (substances consisting of a single chemical element), chemical compounds, or alloys. Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure Water (molecule), water; it has the same properties and the same atomic ratio, ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. Other chemical substances commonly encountered in pure form are diamond (carbon), gold, Edible salt, table salt (sodium chloride) and refined sugar (sucrose). However, in practice, no substance is entirely pure, and chemical purity is specified according to the intended use of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manganese Dioxide
Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cell batteries, such as the alkaline battery and the zinc–carbon battery.. is also used as a pigment and as a precursor to other manganese compounds, such as . It is used as a reagent in organic synthesis, for example, for the oxidation of allylic alcohols. is α polymorph that can incorporate a variety of atoms (as well as water molecules) in the "tunnels" or "channels" between the manganese oxide octahedra. There is considerable interest in as a possible cathode for lithium-ion batteries. Structure Several polymorphs of are claimed, as well as a hydrated form. Like many other dioxides, crystallizes in the rutile crystal structure (this polymorph is called pyrolusite or ), with three-coordinate oxide and octahedral metal centres. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double sugars, are molecules made of two bonded monosaccharides; common examples are sucrose (glucose + fructose), lactose (glucose + galactose), and maltose (two molecules of glucose). White sugar is a refined form of sucrose. In the body, compound sugars are hydrolysed into simple sugars. Longer chains of monosaccharides (>2) are not regarded as sugars, and are called oligosaccharides or polysaccharides. Starch is a glucose polymer found in plants, the most abundant source of energy in human food. Some other chemical substances, such as glycerol and sugar alcohols, may have a sweet taste, but are not classified as sugar. Sugars are found in the tissues of most plants. Honey and fruits are abundant natural sources of simple sugars. Suc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ammonium Hydroxide
Ammonia solution, also known as ammonia water, ammonium hydroxide, ammoniacal liquor, ammonia liquor, aqua ammonia, aqueous ammonia, or (inaccurately) ammonia, is a solution of ammonia in water. It can be denoted by the symbols NH3(aq). Although the name ammonium hydroxide suggests an alkali with chemical formula, composition , it is actually impossible to isolate samples of NH4OH. The ions and OH− do not account for a significant fraction of the total amount of ammonia except in extremely dilute solutions. Basicity of ammonia in water In aqueous solution, ammonia deprotonation, deprotonates a small fraction of the water to give ammonium and hydroxide according to the following chemical equilibrium, equilibrium: : NH3 + H2O NH4+ + OH−. In a 1 Molar concentration, M ammonia solution, about 0.42% of the ammonia is converted to ammonium, equivalent to pH = 11.63 because [NH4+] = 0.0042 M, [OH−] = 0.0042 M, [NH3] = 0.9958 M, and pH = 14 + log10[OHâ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Hydroxide
Potassium hydroxide is an inorganic compound with the formula K OH, and is commonly called caustic potash. Along with sodium hydroxide (NaOH), KOH is a prototypical strong base. It has many industrial and niche applications, most of which exploit its caustic nature and its reactivity toward acids. An estimated 700,000 to 800,000 tonnes were produced in 2005. KOH is noteworthy as the precursor to most soft and liquid soaps, as well as numerous potassium-containing chemicals. It is a white solid that is dangerously corrosive. Properties and structure KOH exhibits high thermal stability. Because of this high stability and relatively low melting point, it is often melt-cast as pellets or rods, forms that have low surface area and convenient handling properties. These pellets become tacky in air because KOH is hygroscopic. Most commercial samples are ca. 90% pure, the remainder being water and carbonates. Its dissolution in water is strongly exothermic. Concentrated aqueous solut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sodium Hydroxide
Sodium hydroxide, also known as lye and caustic soda, is an inorganic compound with the formula NaOH. It is a white solid ionic compound consisting of sodium cations and hydroxide anions . Sodium hydroxide is a highly caustic base and alkali that decomposes proteins at ordinary ambient temperatures and may cause severe chemical burns. It is highly soluble in water, and readily absorbs moisture and carbon dioxide from the air. It forms a series of hydrates . The monohydrate crystallizes from water solutions between 12.3 and 61.8 °C. The commercially available "sodium hydroxide" is often this monohydrate, and published data may refer to it instead of the anhydrous compound. As one of the simplest hydroxides, sodium hydroxide is frequently used alongside neutral water and acidic hydrochloric acid to demonstrate the pH scale to chemistry students. Sodium hydroxide is used in many industries: in the manufacture of pulp and paper, textiles, drinking water, soaps and deterge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Hypomanganate
Potassium hypomanganate is the inorganic compound with the formula . Also known as potassium manganate(V), this bright blue solid is a rare example of a salt with the hypomanganate or manganate(V) anion, where the manganese atom is in the +5 oxidation state. Preparative routes *by two-electron reduction of potassium permanganate with excess potassium sulfite;.. : *by the single-electron reduction of potassium manganate with hydrogen peroxide in 10 M potassium hydroxide solution;. : *by the single-electron reduction of potassium manganate with mandelate in 3–10 M potassium hydroxide solution; : *by disproportionation when manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cell ... is dissolved in a concentrated solution of potassium hydroxide; : The compound is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Manganate
Potassium manganate is the inorganic compound with the formula . This green-colored salt is an intermediate in the industrial synthesis of potassium permanganate (), a common chemical. Occasionally, potassium manganate and potassium ''per''manganate are confused, but these compounds's properties are distinct. Structure and bonding is a salt, consisting of cations and anions. X-ray crystallography shows that the anion is tetrahedral, with Mn-O distances of 1.66 Å, ca. 0.03 Å longer than the Mn-O distances in . It is isostructural with potassium sulfate. The compound is paramagnetic, owing to the presence of one unpaired electron on the Mn(VI) center. Synthesis The industrial route entails treatment of with air: :2 MnO2 + 4 KOH + O2 → 2 K2MnO4 + 2 H2O The transformation gives a green-colored melt. Alternatively, instead of using air, potassium nitrate can be used as the oxidizer: : One can test an unknown substance for the presence of manganese by heating the sample in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Permanganate
Potassium permanganate is an inorganic compound with the chemical formula KMnO4. It is a purplish-black crystalline salt, that dissolves in water as K+ and , an intensely pink to purple solution. Potassium permanganate is widely used in the chemical industry and laboratories as a strong oxidizing agent, and also as a medication for dermatitis, for cleaning wounds, and general disinfection. It is on the World Health Organization's List of Essential Medicines. In 2000, worldwide production was estimated at 30,000 tonnes. Properties Potassium permanganate is the potassium salt of the tetrahedral transition metal oxo complex permanganate, in which four O2- ligands are bound to a manganese(VII) center. Structure KMnO4 forms orthorhombic crystals with constants: ''a'' = 910.5 pm, ''b'' = 572.0 pm, ''c'' = 742.5 pm. The overall motif is similar to that for barium sulfate, with which it forms solid solutions. In the solid (as in solution), each MnO4− centre is t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Hypomanganate
Potassium hypomanganate is the inorganic compound with the formula . Also known as potassium manganate(V), this bright blue solid is a rare example of a salt with the hypomanganate or manganate(V) anion, where the manganese atom is in the +5 oxidation state. Preparative routes *by two-electron reduction of potassium permanganate with excess potassium sulfite;.. : *by the single-electron reduction of potassium manganate with hydrogen peroxide in 10 M potassium hydroxide solution;. : *by the single-electron reduction of potassium manganate with mandelate in 3–10 M potassium hydroxide solution; : *by disproportionation when manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-cell ... is dissolved in a concentrated solution of potassium hydroxide; : The compound is u ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ontario Institute For Studies In Education
The Ontario Institute for Studies in Education of the University of Toronto (OISE/UT) is Canada's only all-graduate institute of teaching, learning and research, located in Toronto, Ontario. It is located directly above the St. George subway station, with the OISE Jackman Institute of Child Study located on Walmer Street by the Spadina station. History OISE/UT traces its origins back to three separate institutions: the Ontario Provincial Normal School, the Faculty of Education at the University of Toronto, and the Ontario Institute for Studies in Education. The Ontario Provincial Normal School was founded in 1847, Provincial Model School in 1848 (later merged into Normal School), renamed the Toronto Normal School in 1875, and renamed again as the Toronto Teachers’ College in 1953. In 1974, the Toronto Teachers’ College was recreated as the Ontario Teacher Education College which was a degree granting institution, in turn with declining need for teachers it was closed by th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox Reaction
Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. There are two classes of redox reactions: * ''Electron-transfer'' – Only one (usually) electron flows from the reducing agent to the oxidant. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * ''Atom transfer'' – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidation reactions are commonly associated with the formation of oxides, other chemical species can serve the same function. In hydrogenation, C=C (and other) bonds ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
