第二章 药物溶液的配制理论-2013.ppt

学习要求（learning objectives） Identify the concept of solution， saturated solution， unsaturated solution， supersaturated solution (掌握溶液、饱和溶液、不饱和溶液、超饱和溶液的概念) 掌握药物溶解度与溶出速度的概念与表示方法，影响药物溶解度与溶出速度的因素及增加药物溶解度与溶出速度的方法。 熟悉药用溶剂的种类及性质；溶解度的测定方法；理解药物在油水两相中分配的含义。 Some Definitions Parts of a Solution SOLUTE(溶质) – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT（溶剂） – the part of a solution that dissolves the solute (usually the greater amount) Solute + Solvent = Solution （溶液） Definitions Solutions can be classified as saturated or unsaturated（不饱和的）. A saturated solution contains the maximum quantity of solute that dissolves at that temperature. An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature Definitions 《中国药典》关于溶解度的描述方法 Definitions SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved 一定温度、压力下，当溶液 中溶质的浓度已超过该温度、 压力下的溶质的溶解度，而溶质仍不析出的现象叫过饱和现象，此时的溶液称为过饱和溶液 Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways: 1. Warm the solvent so that it will dissolve more, then cool the solution 2. Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution Supersaturated Sodium Acetate(醋酸钠) One application of a supersaturated solution is the sodium acetate “heat pack.” 醋酸钠溶解和结晶的反应式为： 当醋酸钠过饱和溶液结晶时，反应向左边进行，放出大量的热 结晶后的溶液可以重新加热使用，循环利用 IONIC COMPOUNDS Compounds in Aqueous Solution Many reactions involve ionic compounds, especially reactions in water — aqueous solutions. Aqueous Solution How do we know ions are present in aqueous solutions? The solutions _______________ They are called ELECTROLYTES HCl, MgCl2, and NaCl are strong electrolytes. They dissociate completely (or nearly so) into ions.? Aqueous Solutions Some compounds dissolve in water but do not conduct electricity. They are called nonelectrolytes. USING MOLARITY What ma