Standard Solution

standard solution

[¦stan·dərd sə¦lü·shən] (analytical chemistry) titrant

Standard Solution

a solution with a known concentration of chemical reagent. Standard solutions are used in titrimetric analysis for establishing the quantity of a particular substance (analyte) by titrating to an equivalence point, usually determined by a change in color of a chemical indicator or of the titrated solution. In order to calculate the results, the amount (volume, sometimes weight) of the standard solution consumed in the reaction with the analyte is established. The accuracy of the determinations depends on the accuracy in establishing the concentration of the standard solution. The concentration of a standard solution is usually expressed in terms of normality. The titer also has certain practical applications.

Standard solutions are obtained in a number of ways. One method involves dissolving an exact weight of a substance in an exact volume of solvent. The substance must be chemically pure and must be stable during storage in solid form and in solution; the composition of this substance must correspond exactly to its chemical formula. A second method involves titration with another solution having a known concentration. This method is convenient in that it does not require exact weighings to determine the concentration of many solutions. Standard solutions can also be prepared by using titrants in the form of dry substances or solutions in amounts required for the preparation of 1 liter of solution of a given concentration. These titrants are produced industrially and are marketed in sealed glass ampuls. Standard solutions must be stored under conditions that ensure a constant composition; here, the chemical nature of the solute must be taken into account.

REFERENCES

Kolthoff, I. M., and V. A. Stenger. Ob’emnyi analiz, vol. 1. Moscow-Leningrad, 1950. (Translated from English.)
Kreshkov, A. P. Osnovy analiticheskoi khimii, 3rd ed. [vol. 2]. Moscow, 1970.
Alekseev, V. N. Kolichestvennyi analiz, 4th ed. Moscow, 1972.

L. V. NIFANTEVA

standard solution

solution

[so-loo´shun] 1. a homogeneous mixture of one or more substances (solutes) dispersed molecularly in a sufficient quantity of dissolving medium (solvent). 2. in pharmacology, a liquid preparation of one or more soluble chemical substances, which are usually dissolved in water. For names of specific solutions, see under the name.3. the process of dissolving or disrupting.4. a loosening or separation.
Preparation of Solutions. Formula for preparing solutions from a pure drug:
For example, to prepare 2000 mL of a 2 per cent solution from boric acid crystals, the proportion would be
Formula for preparing solutions from stock solutions:
For example, to prepare 1000 mL of a 2 per cent solution from a 4 per cent stock solution, the proportion would be aqueous solution one in which water is used as the solvent.BCG solution an aqueous suspension of bacille Calmette-Guérin for instillation into the bladder to activate the immune system in treatment of superficial bladder cancers. It reduces the risk of a subsequent bladder cancer developing, although the exact mechanism of action is unknown. buffer solution one that resists appreciable change in its hydrogen ion concentration (pH) when acid or alkali is added to it.colloid solution (colloidal solution) imprecise term for colloid (def. 3).hyperbaric solution one having a greater specific gravity than a standard of reference.hypertonic solution one having an osmotic pressure greater than that of a standard of reference.hypobaric solution one having a specific gravity less than that of a standard of reference.hypotonic solution one having an osmotic pressure less than that of a standard of reference.isobaric solution a solution having the same specific gravity as a standard of reference.isotonic solution one having an osmotic pressure the same as that of a standard of reference.molar solution a solution in which each liter contains 1 mole of the dissolved substance; designated 1 M. The concentration of other solutions may be expressed in relation to that of molar solutions as tenth-molar (0.1 M), etc.normal solution a solution in which each liter contains 1 equivalent weight of the dissolved substance; designated 1 N.ophthalmic solution a sterile solution, free from foreign particles, for instillation into the eye.saturated solution one in which the solvent has taken up all of the dissolved substance that it can hold in solution.sclerosing solution one containing an irritant substance (sclerosing agent) that will cause obliteration of a space, as in sclerotherapy.standard solution one that contains in each liter a definitely stated amount of reagent; usually expressed in terms of normality (equivalent weights of solute per liter of solution) or molarity (moles of solute per liter of solution).supersaturated solution an unstable solution containing more of the solute than it can permanently hold.volumetric solution one that contains a specific quantity of solvent per stated unit of volume.

stan·dard so·lu·tion

, standardized solutiona solution of known concentration, used as a standard of comparison or analysis.

stan·dard so·lu·tion

, standardized solution (stan'dărd sŏ-lū'shŭn, stan'dărd-īzd) A solution of known concentration, used as a measure of comparison or analysis.