Creates a different molarity, different concentration solutions

Amount of substance concentration

The Amount of substance concentration (Formula symbol: c) or Molarity (outdated term) is the quotient of the amount of substance (n) of a solute X and the volume (V.) of the solution.[1] If the molar mass is known, the mass concentration or - with the help of the Avogadro constant (see also Loschmidt number) - the particle number concentration can be calculated from the molar concentration.

history

It used to be the symbol M. used for the unit of measurement mole per liter and also used together with SI prefixes; however, this notation is not compatible with the International System of Units (SI). According to the IUPAC recommendation, only the substance concentration in English should be included concentration are designated.[2]

Notation

The molar concentration can be given in the unit mole per liter:

$ c_X = \ frac {n_X} {V} \ qquad [c_X] = 1 \ frac {\ rm mol} {\ rm l} $

With a 2.5 molar (outdated representation also: 2.5 M) aqueous sulfuric acid is meant a solution which contains 2.5 mol sulfuric acid molecules per liter at a certain temperature; this is based on the usual unit mol / l;

Sample calculations

In a 0.8 molar (0.8 M) sulfuric acid solution (molar mass of sulfuric acid: 98.08 g / mol) there are 0.8 mol of H per liter of solution2SO4 contain. The corresponding mass at H2SO4 for a volume V. = 3 liters of such sulfuric acid is:

$ m_ {H_2 SO_4} = c_ {H_2 SO_4} \ cdot M_ {H_2 SO_4} \ cdot V = 0 {,} 8 \, \ frac {\ mbox {mol}} {\ mbox {l}} \ cdot 98 { ,} 08 \, \ frac {\ mbox {g}} {\ mbox {mol}} \ cdot 3 {,} 0 \, {\ mbox {l}} = 235 {,} 392 \, {\ mbox {g }} $

The number of particlesN a 3 millimolar (3 mM) solution of cane sugar in water for one volume of solution V. = 2 cubic centimeters, where NA. (Avogadro's constant) indicates the number of particles per mole is:

$ N_ {C_ {12} H_ {22} O_ {11}} = c_ {C_ {12} H_ {22} O_ {11}} \ cdot V \ cdot N_A = 0 {,} 003 \, \ mathrm {\ frac {mol} {dm ^ 3}} \ times 0 {,} 002 \, \ mathrm {dm ^ 3} \ times 6 {,} 022 \ times 10 ^ {23} \, \ mathrm {mol ^ {- 1 }} = 3 {,} 6132 \ cdot \ mathrm {10 ^ {18}} $

See also

Individual evidence

  1. ↑ Entry: amount concentration. In: IUPAC Compendium of Chemical Terminology (the “Gold Book”). doi: 10.1351 / goldbook.A00295.
  2. ↑ IUPAC: Abbreviated list of quantities, units and symbols in physical chemistry. By K. H. Homann. Section 4.3, accessed January 13, 2013.