Solutions composition

Because a mixture, unlike a chemical compound, has a variable composition, the relative amounts of substances in a solution must be specified. The qualitative terms dilute (relatively little solute present) and concentrated large amount of solute) 

Other ways of describing solution composition are also useful. Mass percent (sometimes called weight percent) is the percent by mass of the solute in the solution  

Another way of describing solution composition is the mole fraction (symbolized by the Greek lowercase letter chi, X), the ratio of the number of moles of a given component 

Example State of Solution State of Solute State of Solvent 

Copyright 2010 Cengage Learning, Inc. All Rights Reserved. May not be copied, scanned, or duphcated, in whole or in part. 

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

When liquids are mixed, the liquid present in the largest amount Is called the solvent. 

Because a mixture, unlike a chemical compound, has a variable composition, the relative amounts of substances in a solution must be specified. The qualitative terms dilute (relatively little solute present) and concentrated (relatively large amount of solute) are often used to describe solution content, but we need to define solution composition more precisely to perform calculations. For example, in dealing with the stoichiometry of solution reactions in Chapter 4, we found it useful to describe solution composition in terms of molarity, or the number of moles of solute per liter of solution (symbolized by A/). 

---

Standard potentials are tabulated except when a solution composition is stated the latter are formal potentials and the concentrations are in mol/liter. 

Half-reaction Standard or formal potential Solution composition... 

Sensitivity From equations 10.32 and 10.33 we can see that the sensitivity of a fluorescent or phosphorescent method is influenced by a number of parameters. The importance of quantum yield and the effect of temperature and solution composition on f and p already have been considered. Besides quantum yield, the sensitivity of an analysis can be improved by using an excitation source that has a greater... 

Mayo and collaborators were among the earliest workers to clarify the relationship between copolymer and monomer solution compositions. 

Working Solution Composition. The working solution in an anthraquinone process is composed of the anthraquinones, the by-products from the hydrogenation and oxidation steps, and solvents. The solvent fraction usually is a blend of polar and aromatic solvents which together provide the needed solubiUties and physical properties. Once the solution has been defined, its composition and physical properties must be maintained within prescribed limits for achieving optimum operation. 

Grain size varies widely, from 10 to 5000 nm. The grain size of fine-grained or banded deposits is usually 10—100 nm. Some metals, notably copper, nickel, cobalt and gold, can be deposited in all four types of grain stmcture, depending on the solution composition and plating conditions. 

Disinfectant Formulations and Sterilization. Hundreds of appHcations covering disinfectant compositions using sodium chlorite have been described in U.S. and foreign patents. Some examples of these are as antimicrobial additives for latexes (166), marine antifouling agents (see Coatings, marine) (167,168), antimildew detergent compositions (169), toothpaste and solution compositions for prevention and treatment of periodontal oral disease (see Dentifrices) (170—172), and compositions for the disinfection of contact lenses (qv) (173). 

Fig. 2. SolubiHty diagram for a hypothetical system. The curves AB and BC represent solution compositions that are in equiHbrium with soHds whose compositions are given by the lines AD and CE. If AD and CE are vertical along the respective axes, the crystals are pure R and S, respectively. Crystallization from any solution whose composition is to the left of the vertical line through point B produces crystals of pure R, whereas solutions to the right of the line produce crystals of pure S. A solution whose composition falls on the line through B produces a soHd mixture that has a composition...

As shown in Fig. 18-57, the mutual solubility of two salts can be plotted on the X and Y axes with temperatures as isotherm hues. In the example shown, all the solution compositions corresponding to 100°C with solid-phase sodium chloride present are shown on the Tine DE, All the solution compositions at equihbrium with solid-phase KCl at 100°C are shown by the line EE If both sohd-phase KCl and NaCl are present, the solution composition at equilibrium can only be represented by point E, which is the invariant point (at constant pressure). Connecting all the invariant points results in the mixed-salt hne. The locus of this line is an important consideration in making phase separations. 

For more precise values, computer programs can be used to calculate soluble recoveiy as weh as solution compositions for conditions that are typical of a CCD circuit, with varying underflow concentrations, stage efficiencies, and solution densities in each of the stages. The calculation sequence is easily performed by utihzing material-balance equations around each thickener. 

The peculiarities in selectivity dependences on membrane or on solution composition ... 

Prepare the solutions and measure the pH at one temperature of the kinetic study. Of course, the pH meter and electrodes must be properly calibrated against standard buffers, all solutions being thermostated at the single temperature of measurement. Carry out the rate constant determinations at three or more tempertures do not measure the pH or change the solution composition at the additional temperatures. Determine from an Arrhenius plot of log against l/T. Then calculate Eqh using Eq. (6-37) or (6-39) and the appropriate values of AH and AH as discussed above. 

Shatalov, A. Ya. and Santsova, V. P., Effect of the Solution Composition of Zinc During Uneven Aeration , Sb. Tr. Voroneshsic Otd. Vses. Khim Obshehestva, 2, 89(1959) C.A., 59, I2478g... 

The Operational Characterisics of Platinised-Titanium Anodes Platinised-titanium anodes have the disadvantage that the protective passive him formed when titanium is made anodic in certain solutions can breakdown. This could result in rapid pitting of the titanium substrate, leading ultimately to anode failure. The potential at which breakdown of titanium occurs is dependent upon the solution composition, as is evident from Table 10.16. 

The wastage rate of HSI depends upon the current density and the nature of the soil or water in which the anode is used. HSI is superior to graphite in waters of resistivity greater than 10ohm m, but in waters of 0-5 ohm m and below HSI is susceptible to pitting. From collated experience in fresh water in the pH range 3 to 10 a nominal consumption rate of approximately 0-1 kg A" y" at 20°C has been observed. This is of course dependent upon solution composition and temperature. A number of reports on the performance of HSI anodes in different environments have been produced . ... 

---