Properties of solutions

Some properties of solutions depend on the specific nature of the solute. 

In other words, an effect you can record about the solution depends on the specific nature of the solute. For example, salt solutions taste salty, while sugar solutions taste sweet. Salt solutions conduct electricity (they re electrolytes — see Chapter 6), while sugar solutions don t (they re nonelectrolytes). Solutions containing the nickel cation are commonly green, while those containing the copper cation are blue. 

There s also a group of solution properties that doesn t depend on the specific type of solute — just the number of solute particles. These properties are called colligative properties — properties that simply depend on the relative number of solute particles. The effect you can record about the solution depends on the number of solute particles present. These colligative properties — these effects — include 

Vapor pressure lowering Boiling point elevation Freezing point depression Osmotic pressure 

If a liquid is contained in a closed container, the liquid eventually evaporates, and the gaseous molecules contribute to the pressure above the liquid. The pressure due to the gaseous molecules of the evaporated liquid is called the liquid s vapor pressure. 

The depression of the freezing point. Solutions freeze at lower temperatures than the solvent used to prepare the solutions. 

The depression of the vapor pressure. Solutions have a lower vapor pressure than the pure solvent, both compared at the same temperature. 

Osmotic pressure. The ability of solvent molecules in a solution to pass through a semi-permeable membrane is described by the osmotic pressure of the solution. Solvent passes through the membrane from a solution of lower osmotic pressure into one of higher osmotic pressure. 

Three of the four colligative properties will be examined in this book. 

The properties of sodium silicate solutions at all ratios and concentrations have been described in detail by Vail (1) in 1952. A very convenient summary of data on key properties such as phase diagrams, pH, density, viscosity, and solubility has been 

The specific gravity of a silicate solution is used to determine concentration, if the ratio is known. Otherwise, analysis for silica or alkali is required. Shtyrenkov et al. (20) propose titrating the normality of the alkali, from which the molar ratio of SiOjrNajO can be determined-as 55.16( / - )N - 2.28 where d is specific gravity and N is alkali normality. 

Measurements have been made of certain physical properties of sodium silicate solutions over a wide range of ratios and concentrations. Accurate pH data have been published by Bacon and Wills (21), who used specially designed electrode cells. Densities of the solutions were also reported and an empirical equation given  

Electrical conductivity was measured by Ukihashi (22) on solutions ranging in SiOj NajO ratio from 1.0 to 3.95 and concentrations from 10 N to maximum viscosity. 

The viscosity of 3.41 ratio sodium silicate solutions was measured by Grant and Masson (23) over the concentration range of 0.005-0.3253 g ml and the intrinsic viscosity (specific viscosity divided by concentration) was found to be independent of the shear rate. At a concentration of 0.325 g ml the intrinsic viscosity was 16 ml g at 0.02 g ml it was 3.2 ml g , and at zero concentration the extrapolated value was 3.1 ml g . This demonstrated that the silicate ions were of low molecular weight and lacked chainlike character even in dilute solution. 

Solubility Structure Effects Pressure Effects Temperature Effects (for Aqueous Solutions) 

Freezing-Point Depression Boiling-Point Elevation Freezing-Point Depression 

Opals are formed from colloidal suspensions of silica when the liquid evaporates. 

A solute is the substance being dissolved. The solvent is the dissolving medium. 

In Chapters 10,11, and 12, we explored the properties of pure gases, liquids, and solids. However, the matter that we encounter in our daily lives, such as soda, air, and glass, are frequently mixtures. In this chapter, we examine homogeneous mixtures. 

As we noted in the earlier chapters, homogeneous mixtures are called solutions. aoo (Sections 1.2 and 4.1) 

However, because liquid solutions are the most common, we focus our attention on them in this chapter. 

Each substance in a solution is a component of the solution. As we saw in Chapter 4, the solvent is normally the component present in the greatest amount, and all the other components are called solutes. In this chapter, we compare the physical properties of solutions with the properties of the components in their pure form. We will be particularly concerned with aqueous solutions, which contain water as the solvent and either a gas, liquid, or solid as a solute. 

A solution is formed when one substance disperses uniformly throughout another. The ability of substances to form solutions depends on two factors (1) the natural tendency of substances to mix and spread into larger volumes when not restrained in some way and (2) the types of intermolecular interactions involved in the solution process. 

The size and number of solute particles in different types of mixtures play an important role in determining the properties of that mixture. 

Identify a mixture as a solution, a colloid, or a suspension. Describe how the number of particles in a solution affects the osmotic pressure of a solution. 

Shaving cream, whipped cream, soapsuds Gas Liquid 

Blood plasma, paints (latex), gelatin Solid Liquid 

Suspensions are heterogeneous, nonuniform mixtures that are very different from solutions or colloids. The particles of a suspension are so large that they can often be seen with the naked eye. They are trapped by filters and semipermeable membranes. 

175 Boiling-Point Elevation and Freezing-Point Depression 

Pouring oil and water together makes an immiscile solution. 

Most of the substances we encounter in daily life are mixtures Wood, milk, gasoline, shampoo, steel, and air are all well-known examples. When the components of a mixture are uniformly intermingled—that is, when a mixture is homogeneous—it is called a solution. Solutions can be gases, liquids, or solids, as shown in Table 17.1. However, we will be concerned in this chapter with the properties of liquid solutions, particularly those containing water. Many essential chemical reactions occur in aqueous solutions, since water is capable of dissolving so many substances. 

Example State of Solution State of Solute State of Solvent 

Vodka in watei antifreeze Liquid Liquid Liquid 

Factors Affecting Solubility Structure Effects Pressure Effects 

Unless otherwise noted, all art on this page is ) Cengage Learning 2014. 

Mayonnaise, homogenized miUc, hand lotions Liquid Liquid 

Suspensions are heterogeneous, nonuniform mixtures containing very large particles that are trapped by filters and do not pass through semipermeable membranes. If you stir muddy water, it mixes but then quickly separates as the suspension particles settle to the bottom. Before you use suspensions such as Kaopectate, calamine lotion, antacid mixtures, and liquid penicillin, it is important that you shake well before using to suspend all the particles they contain. 

Water-treatment plants make use of the properties of suspensions to purify water. When chemicals such as aluminum sulfate or iron(lll) sulfate are added to untreated water, they react with small particles to form large suspension particles called oc. In the water-treatment plant, a system of filters traps the suspension particles, but clean water passes through. 

---

The accurate determination of relative retention volumes and Kovats indices is of great utility to the analyst, for besides being tools of identification, they can also be related to thermodynamic properties of solutions (measurements of vapor pressure and heats of vaporization on nonpolar columns) and activity coefficients on polar columns by simple relationships (179). 

In this chapter we shall consider some thermodynamic properties of solutions in which a polymer is the solute and some low molecular weight species is the solvent. Our special interest is in the application of solution thermodynamics to problems of phase equilibrium. 

Osmotic pressure is one of four closely related properties of solutions that are collectively known as colligative properties. In all four, a difference in the behavior of the solution and the pure solvent is related to the thermodynamic activity of the solvent in the solution. In ideal solutions the activity equals the mole fraction, and the mole fractions of the solvent (subscript 1) and the solute (subscript 2) add up to unity in two-component systems. Therefore the colligative properties can easily be related to the mole fraction of the solute in an ideal solution. The following review of the other three colligative properties indicates the similarity which underlies the analysis of all the colligative properties ... 

In this chapter we analyse a wide class of equilibrium problems with cracks. It is well known that the classical approach to the crack problem is characterized by the equality type boundary conditions considered at the crack faces, in particular, the crack faces are considered to be stress-free (Cherepanov, 1979, 1983 Kachanov, 1974 Morozov, 1984). This means that displacements found as solutions of these boundary value problems do not satisfy nonpenetration conditions. There are practical examples showing that interpenetration of crack faces may occur in these cases. An essential feature of our consideration is that restrictions of Signorini type are considered at the crack faces which do not allow the opposite crack faces to penetrate each other. The restrictions can be written as inequalities for the displacement vector. As a result a complete set of boundary conditions at crack faces is written as a system of equations and inequalities. The presence of inequality type boundary conditions implies the boundary problems to be nonlinear, which requires the investigation of corresponding boundary value problems. In the chapter, plates and shells with cracks are considered. Properties of solutions are established existence of solutions, regularity up to the crack faces, convergence of solutions as parameters of a system are varying and so on. We analyse different constitutive laws elastic, viscoelastic. 

The results on contact problems for plates without cracks can be found in (Caffarelli, Friedman, 1979 Caffarelli et al., 1982). Properties of solutions to elliptic problems with thin obstacles were analysed in (Frehse, 1975 Schild, 1984 Necas, 1975 Kovtunenko, 1994a). Problems with boundary conditions of equality type at the crack faces are investigated in (Friedman, Lin, 1996). 

As for approximate methods of finding crack shapes we refer the reader to (Banichuk, 1970). Qualitative properties of solutions to boundary value problems in nonsmooth domains are in (Oleinik et al., 1981 Nazarov, 1989 Nazarov, Plamenevslii, 1991 Nicaise, 1992 Maz ya, Nazarov, 1987 Gris-vard, 1985,1991 Kondrat ev et al., 1982 Kondrat ev, Oleinik, 1983 Dauge, 1988 Costabel, Dauge, 1994 Sandig et al., 1989 Movchan A.B., Movchan N.V., 1995). 

We consider a problem similar to the one considered in Section 2.8. The nonpenetration condition between crack faces is taken in simplified form. Our aim is to obtain some qualitative properties of solutions for a contact problem for a plate having a crack. 

In the book, two- and three-dimensional bodies, plates and shells with cracks are considered. Properties of solutions are established existence of solutions, regularity up to the crack faces, convergence of solutions as parameters of a system are varying and so on. We analyse different constitutive laws elastic, thermoelastic, elastoplastic. The book gives a new outlook on the crack problem, displays new methods of studying the problems and proposes new models for cracks in elastic and nonelastic bodies satisfying physically suitable nonpenetration conditions between crack faces. 

Properties of solutions in contact problems for elastic plates and shells having cracks. 

Table 4. Annealed Tensile Properties of Solution Strengthened Copper Alloys...

From known properties of solution, at measured or calculated concentration. Effective AT if a surface condenser. 

Typical room-temperature properties of solution-annealed plates. 

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. 

UNIFAC was built on the framework of a contemporary model for correlating the properties of solutions in terms of pure-component molecular properties and fitting parameters, viz. UNIQUAC (the universal quasi-chemical) model... 

As noted earlier, colligative properties of solutions are directly proportional to the concentration of solute particles. On this basis, it is reasonable to suppose that, at a given concentration, an electrolyte should have a greater effect on these properties than does a nonelectrolyte. When one mole of a nonelectrolyte such as glucose dissolves in water, one mole of solute molecules is obtained. On the other hand, one mole of the electrolyte NaCl yields two moles of ions (1 mol of Na+, 1 mol of Cl-). With CaCl three moles of ions are produced per mole of solute (1 mol of Ca2+, 2 mol of Cl-). 

Once again, the formation of NH accounts for ammonia having the properties of a base. Reaction (27) produces hydroxide ion, which, by our postulate, accounts for the taste and feel properties of solutions of bases. Reaction (28) shows... 

Systematic studies67) to determine the properties of solutions of the obtained graft copolymers showed that graft copolymers containing stiff main chains (PAA,... 

The test of the validity of the theory of Arrhenius is not therefore to be found in the agreement between the values of i obtained from measurements of any properties of solutions which are conditioned by the osmotic pressure it is in quite another field—that of electrochemistry—that a comparison of known relations with the deductions from the theory may be instituted. 

---