Gases and liquids

The density (absolute) of a liquid or solid is the mass of unit volume of the substance. Generally, however, in using the term density at a given temperature, one really means the relative density, or the density at a given temperature relatively to the density of a standard substance (water) either at the 

The density of liquids is most easily determined by means of vessels of accurately defined volume, called pyknometers. These are made of very varying shapes, but the simplest and most generally useful form is the Ostwald modification of the Sprengel pyknometer (Fig. 6). 

This form of pyknometer, which can be easily made by the student, consists of a moderately wide (10—15 mni.) and rather thin glass tube, to which narrower tubes, a and b, are sealed and bent as shown 

The volume of the pyknometer should be about 5-15 c.c. This will allow of an accuracy of about i unit in the fourth place of decimals, which will be quite sufficient for all our purposes. 

The pyknometer, cleaned and dried, is first weighed empty. For this purpose it is suspended from the end of the balance beam by means of a double hook (Fig. 7), made either from platinum or from copper wire, preferably the 

Because of their closer molecular spacing, liquids normally have higher densities, viscosities, refractive indices, etc., than gases (see Prob. 1.2). In engineering this frequently leads to quite different behaviors of liquids and of gases, as we shall see. 

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In the absence of a single accurate theory representing the physical reality of liquids and gases and, consequently, all their physical properties, a property can be calculated in various ways. 

Numerous types of equations of state apply to solids, liquids, and gases a few of these are considered here. 

Solubility is given in parts by weight (of the formula weight) per 100 parts by weight of the solvent (i.e., percent by weight) and at room temperature. Another unit frequently used is grams per 100 mF of solvent (mF per 100 mF for liquids and gases). The symbols of the common mineral acids represent aqueous solutions of these acids. 

Nitric acid, fuming Organic matter, nonmetals, most metals, ammonia, chlorosulfonic acid, chromium trioxide, cyanides, dichromates, hydrazines, hydrides, HCN, HI, hydrogen sulflde, sulfur dioxide, sulfur halides, sulfuric acid, flammable liquids and gases... 

Converted from tables in Vargaftik, Tables of the Theimophysical Propeities of Liquids and Gases, Nauka, Moscow, 1972, and Hemispbere, Washington, 1975. m = melting point. Tbe notation 2.66.—9 signifies 2.66 X 10. ... 

Liquids and Gases For cocurreut flow of liquids and gases in vertical (upflow), horizontal, and inclined pipes, a veiy large literature of experimental and theoretical work has been published, with less work on countercurrent and cocurreut vertical downflow. Much of the effort has been devoted to predicting flow patterns, pressure drop, and volume fractious of the phases, with emphasis on hilly developed flow. In practice, many two-phase flows in process plants are not fully developed. 

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