The addition of a second component to a pure compound(), resulting in a mixture, will result in a melting point that is lower than that of the pure compound. The degree to which the melting point is lowered is proportional to the mole fraction(NA) of the second component that is added. This can be expressed as: △T=2303 RTTOlOgNA/△Hr AH is the molar heat of fusion T is the absolute equilibrium temperature To is the melting point of pure A, and R is the gas constant
The addition of a second component to a pure compound (A), resulting in a mixture, will result in a melting point that is lower than that of the pure compound. The degree to which the melting point is lowered is proportional to the mole fraction (NA) of the second component that is added. This can be expressed as: T=2.303RTT0 logNA/Hf Hf is the molar heat of fusion T is the absolute equilibrium temperature T0 is the melting point of pure A, and R is the gas constant
Two things are noteworthy in contributing to the extent of melting-point lowering. Evident from this relationship is the inverse proportion between the melting point and the heat of fusion. When a second ingredient is added to a compound with a low molar heat of fusion a large lowering of the melting point is observed Substances with a high molar heat of fusion will show little change in melting point with the addition of a second compound
Two things are noteworthy in contributing to the extent of melting-point lowering. ① Evident from this relationship is the inverse proportion between the melting point and the heat of fusion. - When a second ingredient is added to a compound with a low molar heat of fusion, a large lowering of the melting point is observed; - Substances with a high molar heat of fusion will show little change in melting point with the addition of a second compound
2 The extent of lowering of the melting point is also related to the melting point itself. Compounds with low melting points are affected to a greater extent than compounds with high melting points upon the addition of a second component Low-melting-point compounds will result in a greater lowering of the melting point than those with high melting points
② The extent of lowering of the melting point is also related to the melting point itself. - Compounds with low melting points are affected to a greater extent than compounds with high melting points upon the addition of a second component - Low-melting-point compounds will result in a greater lowering of the melting point than those with high melting points
4) The phase rule(相律) Phase diagrams are often constructed to provide a visual picture of the existence and extent of the presence of solid and liquid phases in binary, ternary and other mixtures 〔相图是通常用于解释和表达固相与液相以 元、三元混合时其存在和范围的可视图 画。)
4) The phase rule （相律） Phase diagrams are often constructed to provide a visual picture of the existence and extent of the presence of solid and liquid phases in binary, ternary and other mixtures. (相图是通常用于解释和表达固相与液相以 二元、三元混合时其存在和范围的可视图 画。）
A phase diagram, or temperature composition diagram, represents the melting point as a function of composition of two or three component systems (相图或温度成分图表示二或三组分系统其 组成与熔点的关系)
◼ A phase diagram, or temperaturecomposition diagram, represents the melting point as a function of composition of two or three component systems. （相图或温度成分图表示二或三组分系统其 组成与熔点的关系）