In Chemistry, What Is the Standard State?

The so-called standard state is the state of the substance at a specified standard pressure p, referred to as the standard state. Generally refers to the temperature T, 100 kPa ^[1] . In order to facilitate the comparison of their relative values in different states, a state needs to be specified as the criterion for comparison.

There are three standard states of gas:

1.The tenth session in 1954

It should be noted that, since the standard state only specifies the pressure p and does not specify the temperature, the standard state of the temperature-dependent state function should indicate the temperature. For comparison, the International Union of Theoretical and Applied Chemistry (IUPAC) recommends selecting 298.15K as the reference temperature. It should be noted that before 1982, IUPAC used 101.325kPa as the standard pressure. When referring to thermodynamic data from a manual or monograph, attention should be paid to its prescribed standard state to avoid misuse of the data. In chemistry, standard temperature and pressure (STP) were once defined as 0 ° C (273.15K) and 101.325kPa (1atm), but since 1992 IUPAC has redefined "standard pressure" as 100 kPa. ^[3]