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Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water.Solutions of HF are colorless, acidic and highly corrosive.A common concentration is 49% (48-52%) but there are also stronger solutions (e.g. 70%) and pure HF has a boiling point near room temperature.
Solid HF consists of zig-zag chains of HF molecules. The HF molecules, with a short covalent H–F bond of 95 pm length, are linked to neighboring molecules by intermolecular H–F distances of 155 pm. [4] Liquid HF also consists of chains of HF molecules, but the chains are shorter, consisting on average of only five or six molecules. [5]
At the interface between the phases (in the classical problem) the temperature is set to the phase change temperature. To close the mathematical system a further equation, the Stefan condition, is required. This is an energy balance which defines the position of the moving interface.
In chemistry, a phase-transfer catalyst or PTC is a catalyst that facilitates the transition of a reactant from one phase into another phase where reaction occurs. Phase-transfer catalysis is a special form of catalysis and can act through homogeneous catalysis or heterogeneous catalysis methods depending on the catalyst used.
In thermochemistry, a thermochemical equation is a balanced chemical equation that represents the energy changes from a system to its surroundings. One such equation involves the enthalpy change, which is denoted with Δ H {\displaystyle \Delta H} In variable form, a thermochemical equation would appear similar to the following:
2 HOF → 2 HF + O 2. This reaction is catalyzed by water. [2] It was isolated in the pure form by passing F 2 gas over ice at −40 °C, rapidly collecting the HOF gas away from the ice, and condensing it: [2] F 2 + H 2 O → HOF + HF. The compound has been characterized in the solid phase by X-ray crystallography [1] as a bent molecule with
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For a gas, it is the hypothetical state the gas would assume if it obeyed the ideal gas equation at a pressure of 1 bar. For a gaseous or solid solute present in a diluted ideal solution , the standard state is the hypothetical state of concentration of the solute of exactly one mole per liter (1 M ) at a pressure of 1 bar extrapolated from ...