Matter states/phases

Traditionally one categorizes matter by phases such as gases, liquids and solids. Chemistry is usually concerned with matter m the gas and liquid phases, whereas physics is concerned with the solid phase. However, this distinction is not well defined often chemists are concerned with the solid state and reactions between solid-state phases, and physicists often study atoms and molecular systems in the gas phase. The tenn condensed phases usually encompasses both the liquid state and the solid state, but not the gas state. In this section, the emphasis will be placed on the solid state with a brief discussion of liquids. 

Intermolecular forces are responsible for the existence of several different phases of matter. A phase is a form of matter that is uniform throughout in both chemical composition and physical state. The phases of matter include the three common physical states, solid, liquid, and gas (or vapor), introduced in Section A. Many substances have more than one solid phase, with different arrangements of their atoms or molecules. For instance, carbon has several solid phases one is the hard, brilliantly transparent diamond we value and treasure and another is the soft, slippery, black graphite we use in common pencil lead. A condensed phase means simply a solid or liquid phase. The temperature at which a gas condenses to a liquid or a solid depends on the strength of the attractive forces between its molecules. 

Figure 6. Solutions of the gap equations and the charge neutrality condition (solid black line) in the /// vs //, plane. Two branches are shown states with diquark condensation on the upper right (A > 0) and normal quark matter states (A = 0) on the lower left. The plateau in between corresponds to a mixed phase. The lines for the /3-equilibium condition are also shown (solid and dashed straight lines) for different values of the (anti-)neutrino chemical potential. Matter under stellar conditions should fulfill both conditions and therefore for //,( = 0 a 2SC-normal quark matter mixed phase is preferable.

An equilibrium exists between a liquid and its vapor. This is just one of several equilibria that exist between the states of matter. A phase diagram is a graph representing the relationship of all the states of matter of a substance. One type of phase diagram relates the states to temperature and pressure. This type allows us to predict which state of matter will exist at a certain temperature and pressure combination. Figure 11-1 shows a general form of a phase diagram. 

In the same way, the behavior of molecules in chemistry determines the state of matter, or phase of a substance. The state of matter tells you how molecules move, behave, and are organized in... 

Finally, we make a few additional remarks. First, note that a pure number state is a3j= state whose phase 0k is evenly distributed between 0 and 2n. This is a consequence of the commutation relation [3] between Nk and e,0 <. Nevertheless, dipole mafKi w elements calculated between number states are (as all quantum mechanical amplitudes) well-defined complex numbers, and as such they have well-defined phajje j S Thus, the phases of the dipole matrix elements in conjunction with the mode ph f i f/)k [Eq. (12.15)] yield well-defined matter + radiation phases that determine the outcome of the photodissociation process. As in the weak-field domain, if only gJ one incident radiation mode exists then the phase cancels out in the rate expres4<3 [Eq. (12.35)], provided that the RWA [Eqs. (12.44) and (12.45)] is adoptedf However, in complete analogy with the treatment of weak-field control, if we irradh ate the material system with two or more radiation modes then the relative pb between them may have a pronounced effect on the fully interacting state, phase control is possible. 

States of matter. Illustration showing three states of matter for water solid (ice), liquid (water), and gas (steam). The state of matter (or phase) of a substance depends on the ambient temperature and pressure. At any combination, there is a dynamic equilibrium between two or more phases. Water at a temperature of 0.072°C and an ambient pressure of 612 Pa has a dynamic equilibrium between all three phases. This is known as its triple point. A fourth phase, the plasma, exists at extremely high temperatures and is normally seen only in elements. (Courtesy of Mehau Kulyk/Scienee Photo Library)... 

See mass. (1) States There are three generally accepted states (phases) in which substances can exist, i.e., solid, liquid, and gas (vapor). From time to time it has been proposed that specialized forms of matter be regarded as states, such as the vitreous (glassy) state, the colloidal state, and the plasma state, but none of these suggestions has gained substantial acceptance. 

The answer is yes and we will digress a bit at this point to introduce these concepts as we did earlier in the chapter. The temperature and pressure conditions that govern physico-chemical behavior of liquids are defined in terms of thermodynamics. The Gibbs Phase Rule is a direct outcome of the physical chemistry of changes in the state of matter. The phase rule helps to interpret the physico-chemical behavior of solids, liquids, and gases within the framework of the kinetic-molecular theory of phase equilibria. 

PHASE CHANGES (SECTION 11.4) A substance may exist in more than one state of matter, or phase. Phase changes are transformations from one phase to another. Changes of a solid to liquid (melting), solid to gas (sublimation), and liquid to gas (vaporization) are all endothermic processes. Thus, the heat of fusion (melting), the heat of sublimation, and the heat of vaporization are all positive quantities. The reverse processes (freezing, deposition, and condensation) are exothermic. 

Chemical reactions of material depend significantly on the state (phase) and degree (size) of aggregation. Thus, clusters, i.e. finite aggregates containing from 2 up to 10" particles, show unique physical and chemical phenomena and allow us to explore the gradual transition from molecular to condensed-matter systems. 

Chapter 5 The States of Matter I Phase Diagrams and Gases... 

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