molecular weight

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weight

 [wāt]
1. heaviness; the degree to which a body is drawn toward the earth by gravity. (See also Tables of Weights and Measures in the Appendix.) Abbreviated wt.
2. in statistics, the process of assigning greater importance to some observations than to others, or a mathematical factor used to apply such a process.
apothecaries' weight see apothecaries' system.
atomic weight the sum of the masses of the constituents of an atom, expressed in atomic mass units (or daltons), in SI units (i.e., kilograms), or as a dimensionless ratio derived by comparing the mass to the mass of an atom of carbon-12, which is taken as 12.000. Abbreviated At wt.
avoirdupois weight see avoirdupois system.
equivalent weight the amount of substance that combines with or displaces 8.0 g of oxygen (or 1.008 g of hydrogen), usually expressed in grams; for acid/base reactions, one equivalent donates or receives a mole of protons and the equivalent weight is the ratio of the molecular weight to the number of protons involved in the reaction. For oxidation-reduction reactions, one equivalent donates or receives a mole of electrons and the equivalent weight is the ratio of the molecular weight to the number of electrons involved in the reaction.
gram molecular weight the molecular weight of a substance expressed in grams; one gram molecular weight of a molecular substance contains one mole of molecules. See also mole1.
low birth weight (LBW) see under infant.
molecular weight the weight of a molecule of a chemical compound as compared with the weight of an atom of carbon-12; it is equal to the sum of the weights of its constituent atoms and is dimensionless. Abbreviated Mol wt or MW. Although widely used, the term is not technically correct; relative molecular mass is preferable.
very low birth weight (VLBW) see under infant.

mo·lec·u·lar weight (mol wt, MW),

the sum of the atomic weights of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now 12C (taken as 12.000). Relative molecular mass (Mr) is the mass relative to the dalton and has no units.
See also: atomic weight.

molecular weight (mol wt)

mo·lec·u·lar weight

(mŏ-lekyū-lăr wāt)
The sum of the atomic weights of all the atoms constituting a molecule; the mass of a molecule relative to the mass of a standard atom, now 12C (taken as 12.000). Relative molecular mass (Mr) is the mass relative to the dalton and has no units.
See also: atomic weight
Synonym(s): molecular weight ratio, relative molecular mass.

molecular weight

The sum of the weights of all the atoms in the molecule.

molecular weight,

n the total atomic mass (weight) of all atoms within a molecule. This determines biologi-cal and physical properties of the substance.

mo·lec·u·lar weight

(mol wt, MW) (mŏ-lekyū-lăr wāt)
The sum of the atomic weights of all the atoms constituting a molecule.
Synonym(s): molecular weight ratio, relative molecular mass.

molecular

of, pertaining to, or composed of molecules.

molecular activity
see enzyme activity.
molecular biology
study of the biochemical and biophysical aspects of the structure and function of genes and other subcellular entities, and of such specific proteins as hemoglobins, enzymes and hormones; it provides knowledge of cellular differentiation and metabolism and of comparative evolution.
molecular layer
layers of cells in both cerebellar and cerebral cortices.
molecular mimicry
see antigenic mimicry.
molecular weight
see molecular weight.

weight

heaviness; the degree to which a body is drawn toward the earth by gravity. See also Tables 4.1 and 4.2.

apothecaries' weight
an outmoded system of weight used in compounding prescriptions based on the grain (equivalent 64.8 mg). Its units are the scruple (20 grains), dram (3 scruples), ounce (8 drams) and pound (12 ounces). See also Tables 4.2 and 4.3.
atomic weight
the weight of an atom of a chemical element, compared with the weight of an atom of carbon-12, which is taken as 12.00000.
avoirdupois weight
the system of weight still used for ordinary commodities in some English-speaking countries. Its units are the dram (27.344 grains), ounce (16 drams) and pound (16 ounces).
birth weight
weight of the newborn at the time of birth.
body weight
the animal's weight. In herbivores this is often debatable because of the variation in 'gut-fill' depending on the availability of palatable food. In the absence of scales the weights of large animals are often estimated on the basis of their age and their girth just behind the elbow. Called also liveweight. See also body condition score.
body weight-to-surface area
determination of many drug dosages is physiologically more accurate when based on body surface area rather than body weight; used particularly in cancer chemotherapy. For conversion table for use in dogs see Table 21.
equivalent weight
the weight in grams of a substance that is equivalent in a chemical reaction to 1.008 g of hydrogen. See also chemical equivalent.
weight gain
increase in body weight for specific periods; the principal measure of productivity in meat animals.
weight loss
the loss of body weight from that previously measured. This estimate must take into account the difference in 'gut-fill' and the effects of developing pregnancy and recent parturition.
metric weight
see Tables 4.1 and 4.2.
molecular weight
the weight of a molecule of a chemical compound as compared with the weight of an atom of carbon-12; it is equal to the sum of the weights of its constituent atoms. Abbreviated mol. wt. See also Table 6.
shifting weight limb to limb
sign indicative of lameness especially in horses; while standing the horse is continually shifting its weight from one limb to the opposite one of the pair.
References in periodicals archive ?
Taking chloroform as an example, the number-average molecular weight of PPO does not change with the increase of chloroform content when chloroform content is below 15 wt%.
Therefore, the numerical computation expression of number-average molecular weight, [bar.
The number-average molecular weights measured by VPO are higher than those measured by GPC.
The average molecular weights, such as the number-average molecular weight [M.
This is one of the facts that explains the discrepancies between the calculated and measured absolute values of the weight-average and number-average molecular weight.
12] have for instance obtained a threefold increase of the number-average molecular weight [M.