Intensive physical properties

Vapor pressure, like density and solubility, is an intensive physical property that is characteristic of a particular substance. The vapor pressure of water at 25°C is 23.76 mm Hg, independent of volume or the presence of another gas. Like density and solubility, vapor pressure varies with temperature for water it is 55.3 mm Hg at 40°C, 233.7 mm Hg at 70°C, and 760.0 mm Hg at 100°C. We will have more to say in Chapter 9 about the temperature dependence of vapor pressure. 

The intensive physical property that relates the mass of an object to its volume is called density. Density, which is simply the mass of an object divided by its... 

Accurate measurement is crucial to scientific experimentation. The units used are those of the Systeme Internationale (SI units). There are seven fundamental SI units, together with other derived units Mass, the amount of matter an object contains, is measured in kilograms (kg) length is measured in meters (m) temperature is measured in kelvins (K) and volume is measured in cubic meters (m3). The more familiar metric liter (L) and milliliter (mL) are also still used for measuring volume, and the Celsius degree (°C) is still used for measuring temperature. Density is an intensive physical property that relates mass to volume. 

An intensive physical property does not change with amount. 

Density, melting and boiling temperatures, and color are intensive physical properties. 

Many systems of color have been developed over time. Early theories about the nature of color existed in many countries of the ancient world. An interest in color was expressed by the Babylonians as early as 1900 B.C. Most early theories assumed that color was one of the properties of matter, such as density or mass. These theories were correct in identifying some physical properties of matter. Color and density are intensive physical properties. They remain constant regardless of amount. Mass, on the other hand, is an extensive physical property of matter. It changes with amount. 

Give one intensive physical property of water and one extensive physical property of water. 

Step 2 Choose a sample size. Since concentration is an intensive physical property, we can choose any sample size we want. A 1-L sample is convenient, because that would contain 0.28 mol of glucose, which is one of the numbers we need to know. We re halfway there ... 

Identify each of the following as an extensive or intensive physical property. (3.1)... 

As an example, it has been pointed out that the Hamaker and Lifshitz theories assume (exphcitly and implicitly, respectively) that intensive physical properties of the media involved such as density, and dielectric constant, remain unchanged throughout the phase—that is, right up to the interface between phases. We know, however, that at the atomic or molecular level solids and liquids (and gases under certain circumstances) exhibit short-range periodic fluctuations they are damped oscillating functions. Conceptually, if one visualizes a hquid in contact with a flat solid surface (Fig. 4.8a), one can see that the molecules (assumed to be approximately spherical, in this case) trapped between the surface and the bulk of the liquid will have less translational freedom relative to the bulk and therefore be more structured. That structure will (or may) result in changes in effective intensive properties near the surface. 

An portion of a material system which is uniform in chemical corrqxtsition and in intensive physical properties. 

A device that converts a chemical or physical property, such as pH or photon intensity, to an easily measured electrical signal, such as a voltage or current. 

The sweet taste of sucrose is its most notable and important physical property and is regarded as the standard against which other sweeteners (qv) are rated. Sweetness is induenced by temperature, pH, sugar concentration, physical properties of the food system, and other factors (18—20). The sweetening powers of sucrose and other sweeteners are compared in Table 3. The sweetness threshold for dissolved sucrose is 0.2-0.5% and its sweetness intensity is highest at 32-38°C (19). 

The physical properties of the fatty acid ethoxylates depend on the nature of the fatty acid and even more on ethylene oxide content. As the latter increases, consistencies of the products change from free-flowing Hquids to slurries to firm waxes (qv). At the same time, odor, which is characteristic of the fatty acid, decreases in intensity. Odor and color stabiUty are important commercial properties, particularly in textile appHcations. Oleic acid esters, though possessing good functional properties, cannot be used because they tend to yellow on exposure to heat and air. 

The phase rule specifies the number of intensive properties of a system that must be set to estabUsh all other intensive properties at fixed values (3), without providing information about how to calculate values for these properties. The field of appHed engineering thermodynamics has grown out of the need to assign numerical values to thermodynamic properties within the constraints of the phase rule and fundamental laws. In the engineering disciplines there is a particular demand for physical properties, both for pure fluids and mixtures, and for phase equiUbrium data (4,5). 

Physical properties of Fullerene Cyg It does not melt below 360°, and starts to sublime at 350° in vacuo. A reddish-brown solid, greenish black in thicker films. Solns are port-wine red in colour. Mixtures of Csq and C70 are red due to C70 being more intensely coloured. It is less soluble than Cso in but also dissolves... 

The Group 1 elements are soft, low-melting metals which crystallize with bee lattices. All are silvery-white except caesium which is golden yellow "- in fact, caesium is one of only three metallic elements which are intensely coloured, the other two being copper and gold (see also pp. 112, 1177, 1232). Lithium is harder than sodium but softer than lead. Atomic properties are summarized in Table 4.1 and general physical properties are in Table 4.2. Further physical properties of the alkali metals, together with a review of the chemical properties and industrial applications of the metals in the molten state are in ref. 11. 

The solid is pale blue the liquid is an intense blue at low temperatures but the colour fades and becomes greenish due to the presence of NO2 at higher temperatures. The dissociation also limits the precision with which physical properties of the compound can be determined. At 25°C the dissociative equilibrium in the gas phase is characterized by the following thermodynamic quantities ... 

The use of the Hammett equation has also been extended to several new types of applications. Since these are not germane to the subject matter of the present chapter, we wiU simply mention work on applications to ethylenic and acetylenic compounds the various applications to physical properties, such as infrared frequencies and intensities, ultraviolet spectra, polarographic half-wave potentials, dipole moments,NMR and NQR spectra,and solubility data and applications to preparative data and biological activity. 

Properties of gold. The color of gold is an intensive property. The quantity of gold in a sample is an extensive property. The fact that gold can be stored in the air without undergoing any chemical reaction with oxygen in the air is a chemical property. The temperature at which gold melts (1063°C) is a physical property. 

Poly(p-pheny lene)s, PPPs, constitute the prototype of rigid-rod polymers and are currently being intensively investigated [1]. The key role of PPPs follows from their conceptually simple and appealing molecular structure, from their chemical stability, and from their superior physical properties [2], In turn, this is the result of important advances made in aromatic chemistry over the last few years. The following section gives an overview of the most common methods to generate poly(p-phenylene)s via different synthetic approaches. 

A surprisingly low concentration of water can reduce the viscosity such that reclaimed PET cannot be used for the blow molding of bottles with acceptable physical properties. The established solution to the moisture problem is to dry the recycled PET in special dryers prior to use. However, the drying process is both time and energy intensive. Paper labels can cause problems in PET recycling if they decompose during washing and removal. The paper fibers formed can produce cellulose fibers that are difficult to remove from the reprocessed PET.1... 

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