concentration solutions - a concept that is quite common in the scientific turnover, and in the household lexicon - characterizes the quantitative structure of the composition of any solution.In accordance with the standards and definitions of the IUPAC (International Register of chemical compounds) under the concentration refers to the ratio of the masses of matter and solution.The measurement of this ratio is performed in units of mole / L or g / L.
If we consider the matter, the proportion of which may be expressed in the same type of values (for example, weight to weight), they are made to reflect the ratio of shares, but the practice was widespread use of the concept is the concentration of solutions.
There are several ways in which you can reflect the concentration.For solutions most commonly used expression in the solution structure of mass and volume (liquid) Percentage can express concentration in moles, moreover, the concentration of the solutions can be expressed in gram equivalents.In some cases, using a variant of reflection concentration using the molar titer or measure.
Typically, the concentration of the solutions which do not require great precision in its expression, showing percentages by weight.However, where high accuracy is required, use moth, titles, or the gram-equivalents.
When using weight percent should apply the rule according to which the concentration of the expression specified in the same units, for example, how many grams of a substance contained in a certain number of grams of the solution.Can not be combined reflected in grams per unit volume (for example: the number of grams of a substance in 100 milliliters of solution).
For example, if we need to express the composition of a 10% solution of common salt, NaCl formula which, it should be understood in a way that includes 100 gram solution of 10 g salt and 90 g of water.In that case, if the concentration is given in terms of percentage of substance (e.g., 25% solution), and the need to use an amount of solution that it was exactly a specified amount of a substance (e.g., 5 g), the solution should be taken forweight (in this example - is 20 g).
For each option has its own reflection concentration formula.So, if you are using percentage concentration of the solution, the formula is as follows:
C = m1 / m, where: m1 - mass of the substance dissolved in the solution and expressed in grams or kilograms, m - mass of the solution, expressed in the sameunits.
molar concentration in the solution is determined by the formula: C (M) = n / V, where n - amount of substance in moles, V - the volume of the solution in liters.By using gram-equivalents formula takes the form: C (N) = z / V, where V - volume of the solution, expressed in liters, z - the number of equivalence.
In those cases where the solution density is known, it is convenient to reflect it by volume.But this is only the case when dealing with rather concentrated solutions (less than 1%), since the error in this case may be negligible.
expressed in number of moles concentration in chemistry called moles.When saying "One molar solution", it means that 1 liter of liquid contained 1 mol of substance.Such a solution is called a "mole."
If the concentration expressed as number of gram-equivalents, which are contained in a unit volume of liquid, in this case, an expression "Normal", which indicates that, for example, in 1 liter of liquid is 1 gram equivalent.Most often, such a solution is simply called normal.
The article deals with only some basic ways of expressing concentration.In other cases, when it comes to sophisticated solutions can be used for this and other units.
