Water treat merit

Most organic substances can be dissolved readily in a suitable organic solvent and some are directly soluble in water or can be dissolved in aqueous solutions of acids (basic materials) or of alkalis (acidic materials). Many inorganic substances can be dissolved directly in water or in dilute acids, but materials such as minerals, refractories, and alloys must usually be treated with a variety of reagents in order to discover a suitable solvent in such cases the preliminary qualitative analysis will have revealed the best procedure to adopt. Each case must be considered on its merits no attempt at generalisation will therefore be made. It is however of value to discuss the experimental technique of the simple process of solution of a sample in water or in acids, and also the method of treatment of insoluble substances. 

B. Duplication method. This is usually applied as the so-called colorimetric titration in which a known volume (x mL) of the test solution is treated in a Nessler cylinder with a measured volume (y mL) of appropriate reagent so that a colour is developed. Distilled water (x mL) is placed in a second Nessler cylinder together with y mL of reagent. A standard solution of the substance under test is now added to the second cylinder from a microburette until the colour developed matches that in the first tube the concentration of the test solution can then be calculated. The standard solution should be of such concentration that it amounts to no more than 2 per cent of the final solution. This method is only approximate but has the merit that only the simplest apparatus is required it will not be discussed further. 

Hydrogen and hydroxide ions can disturb this equilibrium if they combine with the appropriate cation or anion to form less soluble acids or bases. Consequently, the pH of the biological fluid may affect the solubility of a drug and, as a result, its activity. In general, increasing the hydrophilic nature of the salt should increase its water solubility. However, there are numerous exceptions to this generalization, and each salt should be treated on its merits. 

The quality of stripping steam frequently does not receive the attention it merits. The boiler feed water used to produce the steam should be passed through an efficient deaerator and be chemically treated so... 

The theory of liquid water and aqueous solutions has been developed mainly along two routes, both of which have some merits and involve serious approximations. The older approach, recognizing from the outset the immense difficulties involved in treating... 

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