The percentage concentration of solution (the concentration can be calculated by the grams, moles or equivalents of solutes in a certain solution) refers to the percentage by weight of solutes contained in the solution (usually unit solution).
After a soluble substance is dissolved in a solvent, the distribution density of the solvent is expressed as a percentage, which is called the solution percentage concentration (solution mass fraction), and is often expressed as C% (also can be expressed as w).
Solution percentage concentration The calculation formula of solution percentage concentration is:
Mass percentage concentration of solution=solute mass/solution mass × 100%
*Wherein, solute mass+solvent mass=solution mass. [1]
Contained in unit solution solute The amount of is called the concentration of the solution. The more solute content, the greater concentration. Solution concentration can be divided into mass concentration (e.g. mass Percent concentration ）, volume concentration (e.g. molar concentration Normality ）And mass volume concentration. Mass percent concentration
concentration Volumetric concentration
(1) Molar concentration
The concentration of solution is expressed by the number of moles of solute contained in 1L solution, which is called molar concentration, and is expressed by the symbol mol/L, for example, 1L concentrated sulfuric acid If it contains 18.4 mol of sulfuric acid, the concentration is 18.4mol/L. Molar concentration (mol/L)=solute Number of moles /Solution volume (L) The concentration of solution is expressed by the gram equivalent number of solute contained in 1 liter solution, which is called the equivalent concentration, and is expressed by the symbol N.
For example, 1 liter Concentrated hydrochloric acid If it contains 12.0 g equivalent hydrochloric acid (HCl), the concentration is 12.0N. Normality=gram equivalents of solute/solution volume (L)
Mass volume concentration
Use the solute contained in the solution per unit volume (1 cubic meter or 1 liter) Mass number The concentration expressed by is called mass volume concentration, which is expressed by the symbol g/m ³ or mg/L. For example, 1 liter contains chromium waste water Contained in Hexavalent chromium If the mass is 2mg, the concentration of hexavalent chromium is 2mg/L (mg/L) Mass volume concentration=mass of solute (gram or milligram)/volume of solution (cubic meter or liter). [2]
