Often, the terms are called weight rather than mass and used interchangeably. If the average atomic mass (m a) or average molecular mass is known, we can convert it into the molar mass (M) with the help of the molar mass constant (M u). What does gram-molecular weight mean? Because virtually all polymers are mixtures of many large molecules, we have to resort to averages to describe polymer molecular weight. Two experimentally determined values are common: $$M_n$$, the number average molecular weight, is calculated from the mole fraction distribution of different sized molecules in a sample, and $$M_w$$, the weight average molecular weight, is calculated from the weight fraction distribution of different sized molecules. Molar Mass: Molecular Weight: Definition: It is the mass of a mole of a particular substance: It is the mass of a molecule: Unit: Kgmol-1: Atomic mass units: Calculation: It is calculated by dividing the mass of a substance by the amount of the substance: It is calculated as the mass of substance relative to the 1/12 th of the mass of the carbon-12 atom. Molecular mass is a number equal to the sum of the atomic masses of the atoms in a molecule. Also called relative molecular mass . Definition of average molecular weight a. number average molecular weight ( Mn ) Mn= i i Ni (colligative property and end group analysis) b. weight average molecular weight ( Mw) Mw= WiMi (light scattering) N M Wi 7. The definition of molecular weight is directly related to the carbon-12 isotope. 1. They are physical properties of substances and are very useful in … Difference Between Formula Mass and Molecular Mass Definition. Sponsored Links . A molecular weight marker is a molecule used to provide an estimate of the size of molecules subjected to gel electrophoresis.This is a technique in which DNA, RNA, or proteins are separated by size, using an electrical current on a gel.This term should not be confused with molecular markers in genetics — areas in which an organism’s DNA differs from the rest of the population and … ¹ Source: wiktionary.com. The definition of molecular weight is most authoritatively synonymous with molecular mass; however, in common practice, it is also highly variable as are the units used in conjunction with it. Formula Mass: Formula mass is the sum of the masses of atoms present in the empirical formula. The key difference between number average and weight average molecular weight is that the number average molecular weight refers to the mole fraction of molecules in a polymer sample whereas the weight average molecular weight is the weight fraction of molecules in a polymer sample.. The molecular weight of a polymer is a way of describing how long the polymer chains are Each monomer has a molecular weight (often called the formula weight) Adding the monomers together to make polymers increases the molecular weight The longer the chains, the higher the molecular weight . The weight in atomic mass units of each of the atoms in a given formula is the molecular weight of a substance. molecular weight ratio synonyms, molecular weight ratio pronunciation, molecular weight ratio translation, English dictionary definition of molecular weight ratio. Atomic weight is a common name for relative atomic mass, which is defined as the ratio of the average mass of one atom of an element to 1 12 \frac{1}{12} 1 2 1 of the mass of an atom of carbon-12. Thus larger the size of molecule more its contribution to the molecular weight average. molecular weight to be calculated, the peak molecular weight Mp, defined as: Mp = molecular weight of the highest peak Therefore, Mp is the mode of the molecular weight distribution. Molecular weight is either unitless or expressed in terms of atomic mass units (amu) or Daltons (Da). Molecular weight has an important effect on the mechanical properties of polymer, more especially above the glass transition temperature. Molecular Mass Definition . Molecular weight is used in chemistry to determine stoichiometry in chemical reactions and equations. Information and translations of gram-molecular weight in the most comprehensive dictionary definitions resource on the web. Unlike pure compounds, polymers form as a mixture of different molecules (pure compounds contain … Define molecular weight ratio. Definition and molecular weight (molar mass) of some common substances . Definition; History; Inside the atom; Atomic number; Atomic mass; Notation; Molecular weight; Definition. The molecular weight of a substance, also called the molar mass, M, is the mass of 1 mole of that substance, given in M gram. Molecular Weight A molecular weight is simply the weight of one mole (6.022x10^23 molecules) of a compound. Definition of average molecular weight c. z average molecular weight ( MZ ) M Z= NiMi (ultracentrifugation) 2 d. general equation of average molecular weight : M = ( a=0 , Mn … Since larger molecules in a sample … Molecular mass is a number equal to the sum of the atomic masses of the atoms in a molecule. The molecular mass of a molecule is also called the molar mass. n. The sum of the atomic weights of all the atoms in a molecule. Meaning of gram-molecular weight. Molecular weight is a measure of the sum of the atomic weight values of the atoms in a molecule. Effect of Molecular Weight 10 For example, let’s look at hydrocarbons Very short chain … For instance a particular polythylene molecule with $$DP = 1000$$ will have a molecular weight of 28,000. This is because the mass is given per one mole. Like the gram atomic weight, in the case of molecules, we describe the weight of one mole (6.022 x 10^23 molecules) as the gram molecular weight. gram-molecular weight, amount of a molecular substance whose weight, in grams, is numerically equal to the molecular weight molecular weight, weight of a molecule of a substance expressed in atomic mass units (amu). The unified mass unit is related to the molar mass constant (M … Mp is quoted for very narrowly distributed polymers, such as polymer standards used in calibrations. The molecular weight of a polymer is determined by the chemical structure of the monomer units, the lengths of the chains and the extent to which the chains are interconnected to form branched molecules. In practice four averages are used, representing the weighted mean taken with the mole fraction, the weight fraction, and two other functions which can be related to measured quantities: . The molecular weight of a particular polymer molecule is a product of the degree of polymerization and the molecular weight of the repeating unit. The main difference between molar mass and molecular weight is that molar mass gives the mass of a mole of a particular substance whereas molecular weight is the mass of a molecule of a particular substance. Gram molecular weight definition is - the mass of one mole of a compound equal in grams to the molecular weight —called also gram-molecule. Although the definition and units are different for molar mass and molecular weight, the value is the same. Learn more. 1. Weight average molecular weight (M w) measuring system includes the mass of individual chains, which contributes to the overall molecular weight of the polymer. Definition of molar mass averages. The mass of one mole of carbon 12 atoms is exactly 12 grams, which is its molar mass is exactly 12 grams per mole. Definition of Molecular weight. The polymers produced in polymerization … Molecular definition, of or relating to or caused by molecules: molecular structure. or MW. The highest molecular weight polymers are obtained under strictly controlled stoichiometric conditions, that is to say, an exact 1:1 molar ratio of two functional groups is necessary according to the classical theory of polycondensation. 2.4.2 Weight Average Molecular Weight. The sum of the atomic weight's 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). History. See more. (chemistry) the sum of the atomic weights of every atom in a molecule ¹ . It is based on the fact that bigger molecules contain more mass than smaller molecules. relative molecular mass n the sum of all the relative atomic masses of the atoms in a molecule; the ratio of the average mass per molecule of a specified isotopic composition of a substance to one-twelfth the mass of an atom of carbon-12., (Symbol) Mr (Abbrev) r.m.m (Former name) molecular weight Molecular weight is commonly abbreviated by M.W. These are defined below. The molecular mass gives the mass of a molecule relative to that of the 12 C atom, which is taken to have a mass of 12. The mass of one mole of carbon 12 atoms is exactly 12 grams, which is its molar mass is exactly 12 grams per mole. ‘The ethyl group has a greater molecular weight than the smallest alkyl radical which is the methyl group.’ ‘Alcohols and ethers having higher molecular weights do not dissolve well in water, however, because the water molecules can not completely surround those molecules.’ An atomic mass unit is described as 1/12 th the weight of the carbon-12 isotope. ‘The ethyl group has a greater molecular weight than the smallest alkyl radical which is the methyl group.’ ‘Alcohols and ethers having higher molecular weights do not dissolve well in water, however, because the water molecules can not completely surround those molecules.’ A good example is molecular mass or molecular weight. The old symbol was amu, while the most correct symbol is u (a lower-case letter u). Definition of gram-molecular weight in the Definitions.net dictionary. molecular weight meaning: 1. another term for relative molecular mass specialized 2. another term for relative molecular mass…. The molecular mass gives the mass of a molecule relative to that of the 12 C atom, which is taken to have a mass of 12. Different average values can be defined, depending on the statistical method applied. Molecular weight definition: the relative average weight of a molecule of a substance , expressed by a number equal to... | Meaning, pronunciation, translations and examples In the SI system the unit of M is [kg/kmol] and in the English system the unit is [lb/lbmol], while in the cgs system the unit of M is [g/mol]. Search molecular weight and thousands of other words in English definition and synonym dictionary from Reverso. Medical Definition of Molecular weight. Noun. Molecular Mass Definition. 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