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The standard Gibbs free energy of formation (G f °) of a compound is the change of Gibbs free energy that accompanies the formation of 1 mole of a substance in its standard state from its constituent elements in their standard states (the most stable form of the element at 1 bar of pressure and the specified temperature, usually 298.15 K or 25 °C).
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen.Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bonded to oxygen that can dissociate to produce the H + cation and the anion of the acid.
Free energy is made up of an enthalpy term and an entropy term. [11] = The standard enthalpy change can be determined by calorimetry or by using the van 't Hoff equation, though the calorimetric method is preferable. When both the standard enthalpy change and acid dissociation constant have been determined, the standard entropy change is easily ...
A conjugate acid, within the Brønsted–Lowry acid–base theory, is a chemical compound formed when an acid gives a proton (H +) to a base—in other words, it is a base with a hydrogen ion added to it, as it loses a hydrogen ion in the reverse reaction.
For many substances, the formation reaction may be considered as the sum of a number of simpler reactions, either real or fictitious. The enthalpy of reaction can then be analyzed by applying Hess' law, which states that the sum of the enthalpy changes for a number of individual reaction steps equals the enthalpy change of the overall reaction.
This is best illustrated by an equilibrium equation. acid + base ⇌ conjugate base + conjugate acid. With an acid, HA, the equation can be written symbolically as: + + + The equilibrium sign, ⇌, is used because the reaction can occur in both forward and backward directions (is reversible).
Pyrophosphoric acid. In chemistry, a phosphoric acid, in the general sense, is a phosphorus oxoacid in which each phosphorus (P) atom is in the oxidation state +5, and is bonded to four oxygen (O) atoms, one of them through a double bond, arranged as the corners of a tetrahedron.
Diagram of phosphodiester bonds (PO 3− 4) between three nucleotides.The 5' end has a 5' carbon attached to a phosphate, and the other end, the 3' end, has a 3' carbon attached to a hydroxyl group.