In chemistry, the standard state of a material is its state at 1 bar (100 kilopascals). This pressure of 1 bar was recently changed from 1 atm by IUPAC in 1997. The standard state of a material can be defined at any given temperature. When the standard state is referred to in a chemical reaction, it also includes the condition that all solutions are at 1 mol/L or 1 mol/kg. Pure liquids and solids are in their standard states.

For a given material or substance, the standard state is the reference state for the material's thermodynamic state properties such as enthalpy, entropy, Gibbs free energy, and for a lot of other material standards. The standard enthalpy of formation for an element in its standard state is 0.

See also

• Standard temperature and pressure aka STP

External links

• IUPAC definition of standard state
• Standard-state enthalpies

Thermodynamics

Standaardomstandigheden | Warunki standardowe | Condições normais