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After completing this chapter, the reader should be able to:
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► Define and classify liquid systems on the basis of their physical properties.
► List the identification terms, symbols, and definitions of common concentration expressions.
► Clearly understand each concentration expression.
► Solve problems by utilizing concentration expressions and convert from one concentration unit to another.
► Define and demonstrate an understanding of the colligative properties of nonelectrolyte and electrolyte solutions.
► Calculate the molecular weight of a solute from any of the colligative properties.
► Recognize the significance of Liso and ΔTf.
► Calculate osmolarity from concentration and vice versa.
► Show familiarity with the physiologic implications of colligative properties.
► Define an isotonic solution.
► Perform the calculations for preparing an isotonic solution.
► Use the appropriate tables to find freezing point depression values of solutions, sodium chloride equivalent values, and Sprowls' values.
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GENERAL CONSIDERATIONS
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A solution is defined as a chemically and physically homogeneous mixture of two or more substances. Homogeneous is a term used to imply that a mixture is uniform; that is, all the parts are identical. When subjected to routine chemical and physical analysis, the parts test the same. A binary solution is a mixture of only two components. These two components are called the solute and the solvent. For a solution of a solid material in a liquid such as water, the solute is the solid component and the solvent is the liquid component—water in the case of most pharmaceutical applications. The possibilities for a solute and solvent mixture as a solution for all states of matter are 3 × 3 = 9, as shown here:
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Pharmaceutical solutions are mostly solids dissolved in a liquid, which is usually water or water combined with other liquids. They may be named for their use in the patient as outlined here:
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The advantages of solutions as a dosage form ...