molecular formula

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 [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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

em·pir·ic for·mu·la

in chemistry, a formula indicating the kind and number of atoms in the molecules of a substance, or its composition, but not the relation of the atoms to each other or the intimate structure of the molecule.
Synonym(s): molecular formula
Farlex Partner Medical Dictionary © Farlex 2012
References in periodicals archive ?
The molecular formula was established as, C19H34N2O, by HREIMS (m/z 306.2653), requires four degrees of unsaturation.
White solid; Melting point: 196 AoC; Molecular formula: C19H17N4O2Br; UV/Vis[DMSO](I>>max): 306 nm; FT-IR[KBr](cm-1):1217.08 [C-N], 1454.32 [C=C], 1643.35 [C=N], 1697.35 [C=O amide], 3215.33 [-NH amide], 696.30 [C-Br]; GC-MS (m/z): 413 [M]+, 119 [C5H8N2O]+, 147 [C6H4Br]+, 169 [C7H5Br]+, 335 [C19H16N4O2]+.
The molecular formula was established by HREIMS which gave [M+] peak at m/z 846.8222 for C59H106O2 (calcd.
The molecular ion peak was observed at m/z 280.1669 by HRMS revealing the molecular formula C16H24O4, indicating five degrees of unsaturation in the molecule.
The molecular formula was deduced as C30H48O2 by HREIMS, showing M+ peak at m/z 440.3670 (calcd.
The molecular formula was established as C29H48O2 through HREIMS showing M+ peak at m/z 428.6931, (calcd.
Yield: 95 %; m.p.: 107-109 AdegC; Molecular formula: C9H11NO4S; Molecular weight: 229 gmol-1.
The HREIMS showed the molecular ion peak at m/z 576.1280 consistent with the molecular formula C30H24O12 bearing nineteen double bond equivalence (DBE).
1] was obtained as a white amorphous powder with optical rotation +12.9, with molecular formula C41H81NO5 and M+ at m/z 667.
HCl and was filtered, washed with distilled water and air-dried to achieve N-(4-ethoxyphenyl)-2,3-dihydrobenzo-[1,4]dioxin-6-sulfonamide 3 as off-white powder; Yield: 87 %; m.p: 189 degC; Molecular formula: C16H17NO5S; Molecular weight: 335 gmol-1; IR (KBr, cm-1): vmax: 3045 (C-H stretching of aromatic ring), 2988 (-CH2 stretching), 1639 (C=C stretching of aromatic ring) and 1380 (-SO2 stretching); 1H-NMR (CDCl3, 500 MHz, d in ppm): 7.14 (d, J = 7.6 Hz, 2H, H-2' and H-6'), 6.91 (d, J = 7.6 Hz, 2H, H-3' and H-5'), 6.67 (d, J = 1.9 Hz, 1H, H-5), 6.54 (dd, J = 1.4, 8.0 Hz, 1H, H-7), 6.21 (d, J = 6.4 Hz, 1H, H-8), 4.19-4.04 (m, 4H, CH2-2 and CH2-3), 3.21 (q, J = 7.2 Hz, 2H, -OCH2), 1.29 (t, J = 7.0 Hz, 3H, OCH2CH3).
The final residue was CoO hence the molecular formula was suggested to be Co(C6H12NO2S)2.
Yellowish solid (1.1 mg); molecular formula C7H6O2; 1H-NMR (CD3OD, 400 MHz) dH (ppm): 9.77 (1H, s, -CHO), 7.78 (2H, d, J = 8.5 Hz, H-2, 6), 6.92 (2H, d, J = 8.5 Hz, H-3, 5).

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