# 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The Amount of substance concentration (Formula symbol: c) or Molarity (outdated term) is the quotient of the amount of substance (n) of a solute X and the volume (V.) of the solution. 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.

### 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With a 2.5 molar (outdated representation also: 2.5 M) aqueous sulfuric acid is meant a solution which contains 2.5 mol sulfuric acid molecules per liter at a certain temperature; this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}} \$

### 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.