standardtingimustes

Standardtingimustes, Estonian for “under standard conditions,” is a convention used in science to provide a common reference framework for reporting measurements. It designates a specified set of temperature and pressure, and, for solutions, a reference concentration, so results from different experiments can be compared more easily. The exact values vary by discipline, but common anchors are around 25 °C (298.15 K) and 1 atmosphere (101.325 kPa). In chemistry, the standard state of a pure substance is typically at 1 bar, while for solutions the standard state is often a 1 M concentration; standard thermodynamic quantities such as ΔH°, ΔG°, and S° are defined at these conditions.

In gas-related contexts, standard temperature and pressure (STP) has historically meant 0 °C and 1 atm, giving a molar volume of 22.414 L per mole. Some modern conventions use 0 °C and 1 bar, or 25 °C and 1 bar, depending on the organization.

It is important to distinguish standardtingimustes from the broader concept of standard states in thermodynamics. The standard state refers to a defined reference state for a substance at a specified temperature and pressure, while standard conditions describe the practical combination of those values for reporting data. The exact values used should be specified in any report, as small changes can affect calculated properties and comparisons.