molecular weight definition

molecular weight ratio synonyms, molecular weight ratio pronunciation, molecular weight ratio translation, English dictionary definition of molecular weight ratio. 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 weight in atomic mass units of each of the atoms in a given formula is the molecular weight of a substance. 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 is a measure of the sum of the atomic weight values of the atoms in a molecule. 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). The polymers produced in polymerization … ¹ Source: wiktionary.com. 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. 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. 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 … Sponsored Links . Definition and molecular weight (molar mass) of some common substances . Often, the terms are called weight rather than mass and used interchangeably. Different average values can be defined, depending on the statistical method applied. The average atomic mass is measured in the unified mass unit (u). The unified mass unit is related to the molar mass constant (M … 2.4.2 Weight Average Molecular Weight. ‘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.’ Definition; History; Inside the atom; Atomic number; Atomic mass; Notation; Molecular weight; Definition. The definition of molecular weight is directly related to the carbon-12 isotope. 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 . 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 … Meaning of gram-molecular weight. What does gram-molecular weight mean? Molecular Mass Definition. 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: . Definition of gram-molecular weight in the Definitions.net dictionary. 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.. Gram molecular weight definition is - the mass of one mole of a compound equal in grams to the molecular weight —called also gram-molecule. Molecular Weight A molecular weight is simply the weight of one mole (6.022x10^23 molecules) of a compound. Molecular mass is a number equal to the sum of the atomic masses of the atoms in a molecule. (chemistry) the sum of the atomic weights of every atom in a molecule ¹ . Since larger molecules in a sample … n. The sum of the atomic weights of all the atoms in a molecule. Molecular Weight Definition. Molecular weight is used in chemistry to determine stoichiometry in chemical reactions and equations. Formula Mass: Formula mass is the sum of the masses of atoms present in the empirical formula. or MW. Effect of Molecular Weight 10 For example, let’s look at hydrocarbons Very short chain … Molecular weight is either unitless or expressed in terms of atomic mass units (amu) or Daltons (Da). Difference Between Formula Mass and Molecular Mass Definition. The mass of one mole of carbon 12 atoms is exactly 12 grams, which is its molar mass is exactly 12 grams per mole. 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]. Definition of molar mass averages. 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. Information and translations of gram-molecular weight in the most comprehensive dictionary definitions resource on the web. Also called relative molecular mass . Molecular definition, of or relating to or caused by molecules: molecular structure. Noun. Molecular Mass Definition . The mass of one mole of carbon 12 atoms is exactly 12 grams, which is its molar mass is exactly 12 grams per mole. Unlike pure compounds, polymers form as a mixture of different molecules (pure compounds contain … Because virtually all polymers are mixtures of many large molecules, we have to resort to averages to describe polymer molecular weight. 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. 1. Mp is quoted for very narrowly distributed polymers, such as polymer standards used in calibrations. A good example is molecular mass or molecular weight. Learn more. molecular weight meaning: 1. another term for relative molecular mass specialized 2. another term for relative molecular mass…. Although the definition and units are different for molar mass and molecular weight, the value is the same. It is based on the fact that bigger molecules contain more mass than smaller molecules. Molecular mass is a number equal to the sum of the atomic masses of the atoms in a molecule. An atomic mass unit is described as 1/12 th the weight of the carbon-12 isotope. 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. History. Molecular weight has an important effect on the mechanical properties of polymer, more especially above the glass transition temperature. 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). Medical Definition of Molecular weight. The molecular mass of a molecule is also called the molar 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. Weight average molecular weight (M w) measuring system includes the mass of individual chains, which contributes to the overall molecular weight of the polymer. 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. 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). 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. Thus larger the size of molecule more its contribution to the molecular weight average. 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. These are defined below. 1. Molecular weight is commonly abbreviated by M.W. The molecular weight of a particular polymer molecule is a product of the degree of polymerization and the molecular weight of the repeating unit. Protein molecular weight markers, sometimes identified as protein standards or protein ladders, are used to estimate the molecular weight of proteins of interest, to monitor the progress of electrophoretic separation or transfer, and as a positive control for analysis conditions. Define molecular weight ratio. 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. 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 ‘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.’ See more. Molecular weight definition: the relative average weight of a molecule of a substance , expressed by a number equal to... | Meaning, pronunciation, translations and examples For instance a particular polythylene molecule with $$DP = 1000$$ will have a molecular weight of 28,000. They are physical properties of substances and are very useful in … The old symbol was amu, while the most correct symbol is u (a lower-case letter u). Definition of Molecular weight. 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. Search molecular weight and thousands of other words in English definition and synonym dictionary from Reverso.