Physical Properties of Solutions

Many of a solutions properties are determined by the molecular structures of the substances that are in them. In this chapter we will explain the principles underlying a number of familiar everyday phenomena. 

The presence of solutes in water can have profound effects upon the properties of the solvent. These effects include lowering the freezing point, elevating the boiling point, and osmosis. All such properties are called colligative properties they depend upon the concentration of solute, rather than its particular identity. The effects of solutes and solution concentrations on colligative properties are addressed briefly here. 

A sugar cube dissolving in water. The properties of a solution are markedly different from those of its solvent. The solubility of sugar molecules in water is mainly due to hydrogen bond formation between the solute and the solvent. The models show glucose and water molecules. 

Most chemical reactions take place, not between pure solids, liquids, or gases, but among ions and molecules dissolved in water or other solvents. In Chapters 5 and 11 we looked at the properties of gases, liquids, and solids. In this chapter we examine the properties of solutions, concentrating mainly on the role of intermolecular forces in solubility and other physical properties of solution. 

In Section 4.1 we noted that a solution is a homogeneous mixture of two or more substances. Because this definition places no restriction on the nature of the substances involved, we can distinguish six types of solutions, depending on the original states (solid, liquid, or gas) of the solution components. Table 12.1 gives examples of each type. 

Our focus in this chapter will be on solutions involving at least one liquid component—that is, gas-liquid, liquid-liquid, and solid-liquid solutions. And, perhaps not too surprisingly, the liquid solvent in most of the solutions we will study is water. 

Component 1 Component 2 State of Resulting Solution Examples 

In 1993. nine patients who had undergone routine hemodialysis treatment at the University of Chicago Hospitals became seriously ill, and three of them died. The illnesses and deaths were attributed to fluoride poisoning, which occurred when the equipment meant to remove fluoride from the water failed. Although hemodialysis is supposed to remove impurities from the blood, the inadvertent use of fluoridated water in the process actually added a toxin to the patients blood. 

The development and refinement of medical procedures such as hemodialysis require an understanding of the properties of solutions. 

In This Chapter, You Will Learn about the energy changes associated with solution formation, how the concentration of a solution is expressed, and how concentration determines certain properties of a. solution. 

Dialysis uses the properties of solutions to remove harmful substances from the blood. 

At the end of this chapter, you will be able to solve a series of problems related to aqueous fluoride solutions [ M Page 569]. 

As we noted in Seetion 1.2, a solution is a homogeneous mixture of two or more substanees. Reeall that a solution consists of a solvent and one or more solutes [M4 Section 4.1], Althongh many of the most familiar solutions are those in which a solid is dissolved in a liquid (e.g., saltwater or sugar water), the components of a solution may be solid, hqnid, or gas. The possible combinations give rise to seven distinct types of solutions, which we classify by the original states of the solntion components. Table 13.1 gives an example of each type. 

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Unfortunately, any equation that does provide a good fit to a series of experimentally determined data sets, and meets the requirement that all constants were positive and real, would still not uniquely identify the correct expression for peak dispersion. After a satisfactory fit of the experimental data to a particular equation is obtained, the constants, (A), (B), (C) etc. must then be replaced by the explicit expressions derived from the respective theory. These expressions will contain constants that define certain physical properties of the solute, solvent and stationary phase. Consequently, if the pertinent physical properties of solute, solvent and stationary phase are varied in a systematic manner to change the magnitude of the constants (A), (B), (C) etc., the changes as predicted by the equation under examination must then be compared with those obtained experimentally. The equation that satisfies both requirements can then be considered to be the true equation that describes band dispersion in a packed column. 

Physical properties of solutions Hydrodynamic problems and disturbance of the flow profile might appear when solutions with different properties, such as density or viscosity, are introduced into the manifold. 

Phenol-carbohydrate derivatives, in higher plants, 20, 371-408 Photochemistry, of carbohydrates, 18, 9-59 Physical chemistry, of carbohydrates, 15, 11-51 of starch, 11, 335-385 Physical properties, of solutions of polysaccharides, 18, 357-398... 

The mole fraction scale is useful when one is concerned with physical properties of solutions (Chapter 14), which are expressed most clearly in terms of relative numbers of solvent and solute molecules. Sometimes, the physical properties are affected by the number of particles in solution. Then, the molality of ions becomes important, not just that of the molecules—NaCl (Na+ and Cl- in solution) and Na2SC>4 (2Na+ and SO - in solution) affect some physical measurements differently. 

There are two major divisions in a discussion of solutions solution formation and solubility equilibria. The first topic deals with the mechanisms by which solutions form—different ways to describe solutions, factors that affect solution formation, and some of the physical properties of solutions. Those are the domain of this chapter. Solubility equilibria are discussed in Chapter 15, after you ve had a chance to review the concept of equilibrium. 

Largely because of its availability, pyridine is the most frequently used of the nitrogenous, heterocyclic solvents. In the earliest studies,283-285 physical properties of solutions of sucrose in... 

Physical properties of solutions that depend upon the number but not the kind of... 

The further development of modern solution theory is connected with three persons, namely the French researcher Raoult (1830-1901) [28], the Dutch physical chemist van t Hoff (1852-1911) [5], and the Swedish scientist Arrhenius (1859-1927) [6]. Raoult systematically studied the effects of dissolved nonionic substances on the freezing and boiling point of liquids and noticed in 1886 that changing the solute/solvent ratio produces precise proportional changes in the physical properties of solutions. The observation that the vapour pressure of solvent above a solution is proportional to the mole fraction of solvent in the solution is today known as Raoult s law [28]. 

The difficulty in explaining the effects of inorganic solutes on the physical properties of solutions led in 1884 to Arrhenius theory of incomplete and complete dissociation of ionic solutes (electrolytes, ionophores) into cations and anions in solution, which was only very reluctantly accepted by his contemporaries. Arrhenius derived his dissociation theory from comparison of the results obtained by measurements of electroconductivity and osmotic pressure of dilute electrolyte solutions [6]. 

Numerous attempts have been made to calculate relative conformer energies in solution, using physical properties of solutes and solvents, in order to derive theoretical procedures or models with predictive ability [83, 88, 182, 188, 190, 192, 196-198, 274-281], The methods used include quantum-chemical calculations e.g. [198]), statistical... 

Certain physical properties of solutions depend on the concentrations of the particles (molecules or ions) dissolved in the solution, rather than the nature of these solute particles. In this section, we will consider four such colligative properties. The word colligative means depending on the number of particles. ... 

The early chapters in this book deal with chemical reactions. Stoichiometry is covered in Chapters 3 and 4, with special emphasis on reactions in aqueous solutions. The properties of gases are treated in Chapter 5, followed by coverage of gas phase equilibria in Chapter 6. Acid-base equilibria are covered in Chapter 7, and Chapter 8 deals with additional aqueous equilibria. Thermodynamics is covered in two chapters Chapter 9 deals with thermochemistry and the first law of thermodynamics Chapter 10 treats the topics associated with the second law of thermodynamics. The discussion of electrochemistry follows in Chapter 11. Atomic theory and quantum mechanics are covered in Chapter 12, followed by two chapters on chemical bonding and modern spectroscopy (Chapters 13 and 14). Chemical kinetics is discussed in Chapter 15, followed by coverage of solids and liquids in Chapter 16, and the physical properties of solutions in Chapter 17. A systematic treatment of the descriptive chemistry of the representative elements is given in Chapters 18 and 19, and of the transition metals in Chapter 20. Chapter 21 covers topics in nuclear chemistry and Chapter 22 provides an introduction to organic chemistry and to the most important biomolecules. 

Ballou, Clinton E., Alkali-sensitive Glycosides, 9, 59—95 Banks, W., and Greenwood, C. T., Physical Properties of Solutions of Polysaccharides, 18, 357—398 Barker, G. R., Nucleic Acids, 11, 285— 333... 

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