What is the unit of concentration chemistry

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Area of ​​Expertise - General Chemistry

In chemistry, general term for the proportion of a substance in a mixed phase (solid, solution, gas mixture).

Depending on the quantities used, a distinction is made between several concentration measures. What all concentrations have in common is the relationship to the volume of the mixed phase. The most common indication of concentration is the molar concentration (previously: Molarity), in which the amount of a substance is related to the total volume. The unity of Amount of substance concentration is moles per liter (). Under normalcy (Equivalent concentration) is the equivalent amount of a substance (amount of substance multiplied by the valency) per unit of volume. It is not standardized, but it is very common in dimensional analysis for acid-base or redox titrations. Less commonly used concentrations are those Volume concentration, in which the volume of a substance is related to the total volume, and the Mass concentration, which indicates the ratio of the mass of a substance to the total volume.

The Molality a solution is defined as the quotient of the amount of substance of a dissolved substance and the mass of the solvent.

Other, frequently used measures are not concentrations in the strict sense - here the content of a substance is given in percent (also in per mille, symbol: -, or ppm - engl .: part per million - 1 part per 1 million particles): Mass or weight percent (%) means that the mass of the dissolved substance is related to the total mass and this value is multiplied by 100. Calculate analogously Volume percent (Vol-%) and Mole percent (Mol%) (amount of substance of the solute / total amount of substance of the solution × 100). The respective quotients are called partial / total Crowds-, volume- or. Breakwater (also Crowds-, volume- or Substance content).

Many thermodynamic and electrochemical relationships usually contain activities instead of concentrations (effective concentrations, see equation), since calculations with concentration usually only lead to correct results with ideally diluted solutions.

See also: activity

Learning units in which the term is dealt with

potassium20 min.

chemistryInorganic chemistryChemistry of the elements

This learning unit gives an overview of the alkali metal potassium including occurrence, extraction, properties, reaction behavior and use of the element as well as selected compounds.

Activity versus concentration15 minutes.

chemistryGeneral Chemistryliquids

There is a relationship between activity and concentration. This relationship is discussed in more detail in the learning unit.

Phase diagrams of binary systems90 min.

chemistryPhysical chemistrythermodynamics

The learning unit deals with the simplest phase diagrams of binary systems. Phase diagrams of ideal and non-ideal mixtures are discussed. It describes what changes a system undergoes when the temperature or the composition is changed.

Speed ​​of chemical reactions30 min.

chemistryPhysical chemistrykinetics

The subject of reaction kinetics is the investigation of the time behavior of a chemical reaction, briefly referred to as the speed of a chemical reaction. The key variable is the so-called reaction speed, abbreviated to RG, the definition and basic characteristics of which are presented here.