Meaning of Chemical Concentration

What is Chemical concentration:

chemical concentration determines the ratio of solute and solvent in a chemical solution.

The chemical concentration is the amount in which the substances that dissolve (solute) are found in relation to the substance or substances that dissolve it (solvent). In this sense, the amount of solute will always be less than the solvent for it to be considered a solution.

The preparation of a chemical solution requires calculating the measurements of solute and solvent that will determine the concentration of the solution and the type of solution.

Solution concentrations are expressed by molarity, molality, or mole fraction.

Chemical concentration measurements

The concentration measures of chemical solutions are determined by physical units and chemical units of concentration:

The physical units are those that define the ratio between the solute and the solvent in mass, volume or its parts.

Chemical units, on the other hand, define the concentration of the solution by moles or chemical equivalents that the solvent presents.

Physical units of concentration of solutions

The physical units of concentration of solutions express the proportion of solute in weight, volume or parts, with respect to the amount of solvent. The exercises to calculate the percentage by mass or weight, that is, its concentration expressed in those measurements, divide the solute measurements by the solvent and then multiply by 100.

The physical measures of chemical concentrations and their formulas are as follows:

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weight on weight

Weight on weight (% w/w), or also mass on mass (m/m) expresses the percentage of weight or mass of solute in relation to the weight or mass of solution:

weight for weight

volume over volume

Volume by volume (%v/v) indicates the proportion of the volume of the solute in the total volume of the solution:

volume by volume

weight over volume

Weight over volume (% w/v) represents the weight of the solute in relation to the volume of the solution:

weight per volume

Parts per million

Parts per million (ppm) calculates the milligrams of solute in kilograms of solution:

ppm

Chemical units of concentration of solutions

Chemical units of solution concentration calculate the number of moles or chemical equivalents of a solute in a solvent. The chemical measures of concentration and their respective formulas are:

Molarity (g/L)

Molarity is the number of moles of solute in liters of solution. A mole is a number of carbon atoms expressed in Avogadro’s constant. To determine the number of moles or molar mass of an element, it is enough to consult a periodic table. The number below the element’s chemical symbol and is also known as the atomic mass.

To calculate the molarity of a solution, the following formula must be used:

molarity

To determine the number of moles of a solute, the mass of the solute must be calculated using the following formula:

solute mass

In this case, the molar mass is calculated by multiplying the atomic mass of each element by the number of atoms indicated in the formula, and then adding the result for each element.

For example, to calculate the molar mass of 100 grams of ammonia (NH3) as a solute, first determine the molar mass of ammonia by adding the atomic masses of nitrogen (1.008) with the three hydrogen atoms (3*14.01) obtaining 43.038 g /mol. Then, divide the grams by the molar mass: 100 / 43.038 = 2.323 moles in 100 grams of ammonia.

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See also Molar mass.

molality

For the preparation of solutions of concentrations of a certain amount of molality, the following formula is used:

molality

To calculate the moles of a solute, the atomic mass or molar mass found under each chemical element on the periodic table is sought.

Normality (N)

Normality is the number of chemical equivalents (EQ) in one gram of solute contained in one liter of solution. Chemical equivalents is the amount of substance that reacts to produce one mole of product.

Normality is also known as normal concentration and is calculated using the following formula:

Normal

To calculate the chemical equivalent (EQ) of a solute, one must take into account whether the solute is an acid or a hydroxide (OH) and use the following formulas depending on the corresponding solute:

chemical equivalents

See also:

  • Chemical solution
  • Concentration
  • solute and solvent.