Principles of solution chemistry

Preparing solutions - practical advice is given on p. 15. A solution is a homogeneous liquid, formed by the addition of solutes to a solvent. The behaviour of solutions is determined by the type of solutes involved and by their proportions, relative to the solvent. Many laboratory exercises involve calculation of concentrations, e.g. when preparing an experimental solution at a particular concentration, or when expressing data in terms of solute concentration. Make sure that you understand the basic principles set out in this chapter before you tackle such exercises. Solutes can affect the properties of solutions in several ways, as follows. 

Definition Electrolyte - a substance that dissociates, either fully or partially, in water to give two or more ions. Electrolytic dissociation This occurs where a substance dissociates to give charged particles (ions). For a strong electrolyte, e.g. Na+Cl, dissociation is essentially complete. In contrast, a weak electrolyte, e.g. ethanoic acid, will be only partly dissociated, depending upon the pH and temperature of the solution (p. 57). 

Do not confuse the solubility of a chemical with its strength as an electrolyte. Ethanoic acid is completely soluble with water in all proportions, yet it is a weak electrolyte because it is only partially dissociated. Barium hydroxide is very insoluble in water, but the small quantity which does dissolve (see Ks below) is dissociated completely into Ba2 r and OH ions thus it is a strong electrolyte. Osmotic effects These are the result of solute particles lowering the effective concentration of the solvent (water). These effects are particularly relevant to biological systems since membranes are far more permeable to water than to most solutes. Water moves across biological membranes from the solution with the higher effective water concentration to that with the lower effective water concentration (osmosis). Ideal 1 non-ideal behaviour This occurs because solutions of real substances do not necessarily conform to the theoretical relationships predicted for dilute solutions of so-called ideal solutes. It is often necessary to take account of the non-ideal behaviour of real solutions, especially at high solute concentrations (see Lide (2000) for appropriate data). 

Example A 1.0 molar solution of NaCI would contain 58.44 g NaCI (the molecular mass) per litre of solution. Molarity This is the term used to denote molar concentration, [C], expressed as moles of solute per litre volume of solution (moIL-1). This non-SI term continues to find widespread usage, in part because of the familiarity of working scientists with the term, but also because laboratory glassware is calibrated in 

1 Useful procedures for calculations involving molar concentrations 

Electrolyte - a substance that dissociates.i. .eith fully - Sr partially, in water to give 3 two OK more ions. - - 

Solutes can affect the properties of solutions in several ways, as follows. 

These are the result of solute particles lowering the effective concentration of the solvent (water). These effects are particularly relevant to biological systems since membranes are far more permeable to water than to most solutes. Water moves across biological membranes from the solution with the higher effective water concentration to that with the lower effective water concentration (osmosis). 

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Art forgeries are detected by chemical means. Art restoration and conservation is accomplished through applying the principles of solution chemistry. We have a true and faithful marriage of art and chemistry when we restore or conserve artwork and when we discover art forgeries. In these endeavors, art and chemistry will never be divorced. 

Finally, it is understood that the reader is aware of the basic principles of solution chemistry of lanthanides and actinides. Besides all the information published in the previous issues of this Handbook for lanthanides, excellent reviews exist on these topics, either on a general (Katz et al., 1986 Biinzli and Choppin, 1989 Grenthe, 1992 Choppin, 1997 Biinzli, 1998) or an historical perspective (Morss and Fuger, 1992). 

In this chapter, we introduced the reader to some basic principles of solution chemistry with emphasis on the C02-carbonate acid system. An array of equations necessary for making calculations in this system was developed, which emphasized the relationships between concentrations and activity and the bridging concept of activity coefficients. Because most carbonate sediments and rocks are initially deposited in the marine environment and are bathed by seawater or modified seawater solutions for some or much of their history, the carbonic acid system in seawater was discussed in more detail. An example calculation for seawater saturation state was provided to illustrate how such calculations are made, and to prepare the reader, in particular, for material in Chapter 4. We now investigate the relationships between solutions and sedimentary carbonate minerals in Chapters 2 and 3. 

The principles of solution chemistry known from elementary handbooks apply in a concentration range of about 10 — M. The procedures and methods that work very well at concentrations greater than 10 M must not be extrapolated to lower concentrations. This is because distilled water used in the laboratory is not pure water, but contains dissolved components of air, materials leached from the container (e.g., silica), and other components. The contribution of the solutes to the physical and chemical properties of water is negligible when their concentrations are low enough, and the presence of impurities in distilled water can be... 

In the second part of the article (Section 3) we examine the possible involvement of electrochemical processes in metabolic regulation. Current concepts based on the principles of solution chemistry are critically reviewed and the advantages of an alternative electrochemical approach are demonstrated. The question of what factors govern overall metabolic rate as manifested by 02-uptake and heat production in the living cell or organism are explored from an electrochemical viewpoint. 

Intravenous Solutions to Teach Some Principles of Solution Chemistry /. Chem. Educ., Vol. 59,1982, 725. 

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