数均分子量 - 百度百科
数均分子量（Number-average Molecular Weight），聚合物是由化学组成相同而聚合度不等的同系混合物组成的，即由分子链长度不同的高聚物混合组成。 通常采用平均数分子量表征分子的大小。 按分子数目统计平均，则称为数均分子量，符号为 (Mn)。
Molar mass distribution - Wikipedia
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: Number average molar mass (Mn), also loosely referred to as number average molecular weight (NAMW).
Number Average Molecular Weight - an overview - ScienceDirect
It is determined by measuring the molecular weight of n molecules, summing the weights, and dividing by n. The weight average molecular weight is a way of describing the molecular weight of a complex mixture such as crude oil even if the molecular constituents are not of the same type and exist in different sizes.
Polymer Chemistry: Molecular Weight Averages
Two of the most important are the number-average and the weight-average molecular weights. Suppose that you have a set of values {x 1, x 2, . . ., x n} for which you calculate an average value. If the probability of each value occurring are given by {P 1, P 2, . . ., P n} then the average is given by the sum below.
NUMBER-AVERAGE AND WEIGHT-AVERAGE MOLECULAR …
2022年11月17日 · A polymer’s molecular weight uses either the number fraction or the weight fraction of the molecules present in the polymer to get either the number-average molecular weight or the weight average molecular weight.
Number Average vs. Weight Average Molecular Weight
Number Average Molecular Weight is calculated by summing up the products of the molecular weight of each polymer species and its corresponding number of molecules, and then dividing it by the total number of molecules in the sample.
2.2: Molecular Weight Determination - Chemistry LibreTexts
2022年8月28日 · Weigh (15 to 20 grams) of the pure solvent in a test tube and record the measured weight value of the pure solvent. Place a stir bar or wire stirrer in the test tube and close with a rubber stopper that has a hole to encase a mercury thermometer. Place a mercury thermometer in the rubber stopper hole.
Molecular Weights of Polymers - Chemistry LibreTexts
2023年1月23日 · Two experimentally determined values are common: Mn M n, the number average molecular weight, is calculated from the mole fraction distribution of different sized molecules in a sample, and Mw M w, the weight average molecular weight, is calculated from the weight fraction distribution of different sized molecules. These are defined below.
数均分子量怎么计算 教你如何正确计算 - 百度知道
1、数均分子量计算公式：Mn=∑NM/∑N。 2、数均分子量（Number-average Molecular Weight），聚合物是由化学组成相同而聚合度不等的同系混合物组成的，即由分子链长度不同的 高聚物 混合组成。 通常采用 平均数 分子量表征分子的大小。 按分子数目统计平均，则称为数均分子量，符号为 (Mn)。 3、数均分子量=求和各组分分子量*组分摩尔数/总摩尔数。 常用聚合物稀溶液的冰点降低，沸点升高， 渗透压 法和端基滴定法等依数性方法来测定,其意义是某体系的总质 …
Number Average Molecular Weight - Fiveable
Number average molecular weight (M_n) is a measure of the average mass of polymer molecules in a sample, calculated by dividing the total mass of all the polymer chains by the total number of chains.
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