In chemistry, hydronium is the common name for the aqueous cation H 3O+, the type of oxonium ion produced by protonation of water. It is the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H+) to the surrounding water molecules (H2O). == Determination of pH == It is the presence of hydronium ion relative to hydroxide that determines a solution's pH. The molecules in pure water auto-dissociate into hydronium and hydroxide ions in the following equilibrium: 2 H 2O ⇌ OH− + H 3O+ In pure water, there...

In chemistry, resonance or mesomerism is a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by one single Lewis structure. A molecule or ion with such delocalized electrons is represented by several contributing structures (also called resonance structures or canonical structures). Each contributing structure can be represented by a Lewis structure, with only an integer number of covalent bonds between each pair of atoms within the structure. Several Lewis structures are used collectively to describe the actual molecul...

Sulfur hexafluoride (SF6) is an inorganic, colorless, odorless, non-flammable, extremely potent greenhouse gas, which is an excellent electrical insulator. SF 6 has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, it is poorly soluble in water but quite soluble in nonpolar organic solvents. It is generally transported as a liquefied compressed gas. It has a density of 6.12 g/L at sea level conditions, considerably higher than the density of air (1.225 g/L). == Synthesis and reactions == SF 6 can...

In chemistry, methanium is a positive ion with formula CH+ 5, namely a molecule with one carbon atom bonded to five hydrogen atoms and bearing a +1 electric charge. It is a superacid and one of the onium ions, indeed the simplest carbonium ion. Methanium can be produced in the laboratory as a rarefied gas or as a dilute species in superacids. It was prepared for the first time in 1950 and published in 1952 by Victor Talrose and his assistant Anna Konstantinovna Lyubimova. It occurs as an intermediate species in chemical reactions. The methanium ion is named after methane (CH 4), by analogy with...

According to the classical definition, a superacid is an acid with an acidity greater than that of 100% pure sulfuric acid, which has a Hammett acidity function (H0) of −12. According to the modern definition, superacid is a medium in which the chemical potential of the proton is higher than in pure sulfuric acid. Commercially available superacids include trifluoromethanesulfonic acid (CF3SO3H), also known as triflic acid, and fluorosulfuric acid (HSO3F), both of which are about a thousand times stronger (i.e. have more negative H0 values) than sulfuric acid. Strong superacids are prepared by the...