empirical formula


Also found in: Dictionary, Thesaurus, Encyclopedia, Wikipedia.

formula

 [for´mu-lah] (pl. formulas, for´mulae) (L.)
1. an expression, using numbers or symbols, giving the directions for preparing a compound (such as a medicine) or giving a procedure to follow to obtain a desired result.
2. a mixture for feeding an infant, usually with cow's milk as a base, supplemented with vitamins and minerals. Various formulas are available, differing in protein, fat, and carbohydrate content in order to meet the nutritional requirements or restrictions of individual infants.
chemical formula a combination of symbols used to express the chemical components of a substance.
empirical formula a chemical formula that expresses the proportions of the elements present in a substance.
molecular formula a chemical formula expressing the number of each element present in a substance, without indicating how they are linked.
spatial formula (stereochemical formula) a chemical formula giving the numbers of atoms of each element present in a molecule of a substance, which atom is linked to which, the types of linkages involved, and the relative positions of the atoms in space.
structural formula a chemical formula showing the spatial arrangement of the atoms and the linkage of every atom.
References in periodicals archive ?
The empirical formulas about spindle speed indicate that the milling force decreases with the increase in the spindle speed, which is caused by the increase in diamond abrasive particle per unit time; the reason is that the maximum milling thickness of single diamond abrasive particle decreases with the increase in diamond abrasive particle per unit time.
Formula (3) which states the relationship between microbending loss and the retraction displacement of optical fiber is an empirical formula, but the shearing displacement of landslide mass would not been calculated directly through fiber optic microbend loss by formula (3).
Specifically, the increase magnitude and empirical formula shown in Figure 9 are adapted to more general situations and expressed as Equation (22).
(3) By curve fitting of the experimental data, an empirical formula of the frictional loss factor in turbulent flow for raw sewage was determined as [[lambda].sub.ts] = 0.3208/[([Re.sub.s]).sup.0.27].
(2) The dimensionless empirical formula of spacing threshold is obtained via multivariate regression analysis, and its accuracy is satisfactory.
Since it is difficult to obtain analytical design formula of such a complicated phase shifter, empirical formula derived by measured or full-wave simulated results is adopted.
In both cases, the samples obtained from mechanical and ultrasound agitation produced similar empirical formulas ([C.sub.7][N.sub.1][H.sub.7]).
Each monograph includes information on nonproprietary names, synonyms, chemical name and Chemical Abstracts Service registry number, empirical formula and molecular weight, structural formula, functional category, applications in pharmaceutical formulation or technology, description, pharmacopoeial specifications, typical properties, stability and storage conditions, incompatibilities, method of manufacture, safety, handling precautions, regulatory status, related substances, specific and general references, and date of revision.
Deflection rate of the system "anchor-roof" by the anchor torque measurements was on average 1.3 mm/t, where loads on used anchors (N) was determined by the empirical formula 0.2722 N = M (M is anchor torque).
Figures 3, 4, and 5 show the comparison of data with the method recommended by ASHRAE Handbook, Shah's empirical formula (Equation 14a), and Shah's analytical formula (Equation 11).
For example, both stearic acid and isostearic acid have the same empirical formula and same molecular weight, but they have dissimilar physico-chemical properties.
The empirical formula ofg the rhodonite based on 5 (Si,Al)[O.sub.4] groups is:

Full browser ?