Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Properties of Gases Gas Pressure

The greenish yellow gas is Cl2(g) the brownish red gas is Br2(g) above a small pool of liquid bromine the violet gas is bfg) in contact with grayish-black solid iodine. Most other common gases, such as H2, O2, N2, CO, and CO2, are colorless. [Pg.195]

For a quantitative description of the behavior of gases, we will employ some simple gas laws and a more general expression called the ideal gas equation. These laws will be explained by the kinetic-molecular theory of gases. The topics covered in this chapter extend the discussion of reaction stoichiometry from the previous two chapters and lay some groundwork for use in the following chapter on thermochemistry. The relationships between gases and the other states of matter— liquids and solids—are discussed in Chapter 12. [Pg.195]

Some characteristics of gases are familiar to everyone. Gases expand to fill their containers and assume the shapes of their containers. They diffuse into one another and mix in all proportions. We cannot see individual particles of a gas, although we can see the bulk gas if it is colored (Fig. 6-1). Some gases, such as hydrogen and methane, are combustible whereas others, such as helium and neon, are chemically unreactive. [Pg.195]

Four properties determine the physical behavior of a gas the amount of the gas (in moles) and the volume, temperature, and pressure of the gas. If we know any three of these, we can usually calculate the value of the remaining one by using a mathematical equation called an equation of state (such as the ideal gas equation, given on page 206). To some extent we have already discussed the properties of amount, volume, and temperature, but we need to consider the idea of pressure. [Pg.195]

The two cylinders have the same mass and exert the same force on the supporting surface (F = g X m). The tall, thin one has a smaller area of contact, however, and exerts a greater pressure (P = F/A). [Pg.195]


You have learned that the temperature of a gas is related to the kinetic energy of the gas molecules. Now you will learn about other properties of gases, including pressure, volume, and amount of gas present, and about the relationships among these properties. [Pg.341]

Balloonists, such as those in the photo at the beginning of this chapter, are making use of a physical property of gases if pressure is constant, gases expand when heated. When the temperature increases, the volume of a fixed number of gas molecules must increase if the pressure is to stay constant. At the higher temperature, the gas molecules move faster. They collide with the walls of the container more frequently and with more force. The volume of a flexible container must then increase in order for the pressure to remain the same. [Pg.351]

In this way MTPM distinguishes between transport properties of gases (gas viscosity, binary bulk-diffusion coefficients of all gas pairs) and textural properties of porous materials characterized by the set of transport parameters (, , ly). Transport parameters represent material properties of the porous solid, and, thus do not depend on temperature, pressure and the kind of used gases. The obtained transport characteristics have a wide practical use for simulation and prediction in many industrial processes (e.g. calculation of effective diffusion coefficients for any pairs of gases in automotive catalytic converter [11]). [Pg.218]

A substance is in the ideal gas state when the volume of its molecules is a zero fraction of the total volume taken up by the substance and when the individual molecules are far enough apart from each other so that there is no interaction between them. Although this only occurs at infinite volume and zero pressure, in practice, ideal gas properties can be used for gases up to a pressure of two atmospheres with little loss of accuracy. Thermal properties of ideal gas mixtures may be obtained by mole-fraction averaging the pure component values. [Pg.391]

Pressure, temperature, and volume are properties of gases that are completely interrelated. Boyle s law and Charles law may be combined into one equation that is referred to as the ideal gas law. This equation is always true for ideal gases and is true for real gases under certain conditions. [Pg.557]

The fugacity coefficient is a function of pressure, temperature, and gas composition. It has the useful property that for a mixture of ideal gases (Pi = 1 for all i. The fugacity coefficient is related to the volumetric properties of the gas mixture by either of the exact relations (B3, P5, R6) ... [Pg.144]

A remarkable characteristic of gases is that many of their physical properties are very similar, particularly at low pressures, regardless of the identity of the gas. Therefore, instead of having to describe the properties of each gas individually, we can describe them all simultaneously. [Pg.262]

Summaries of the properties of gases, particularly the variation of pressure with volume and temperature, are known as the gas laws. The first reliable measurements of the properties of gases were made by the Anglo-Irish scientist Robert Boyle in 1662 when he examined the effect of pressure on volume. A century and a half later, a new pastime, hot-air ballooning, motivated two French scientists, Jacques Charles and Joseph-Louis Gay-Lussac, to formulate additional gas laws. Charles and... [Pg.266]

The simplest state of matter is a gas. We can understand many of the bulk properties of a gas—its pressure, for instance—in terms of the kinetic model introduced in Chapter 4, in which the molecules do not interact with one another except during collisions. We have also seen that this model can be improved and used to explain the properties of real gases, by taking into account the fact that molecules do in fact attract and repel one another. But what is the origin of these attractive and... [Pg.299]

Like a iiquid or a soiid, a gas can be characterized by its voiume (V), temperature (T), and amount (n). Unlike iiquids and soiids, however, the properties of gases are highiy sensitive to pressure (P). We can understand this sensitivity using the moiecuiar perspective. [Pg.281]

In this chapter, you learned about the properties of gases. You learned that you can use the combined gas law, the ideal gas law, or the individual gas laws to calculate certain gas quantities, such as temperature and pressure. You also learned that these equations could also be useful in reaction stoichiometry problems involving gases. You learned the postulates of the Kinetic-Molecular... [Pg.93]

Although the two scales are identical numerically, their conceptual bases are different. The ideal gas scale is based on the properties of gases in the limit of zero pressure, whereas the thermodynamic scale is based on the properties of heat engines in the limit of reversible operation. That we can relate them so satisfactorily is an illustration of the usefulness of the concepts so far defined. [Pg.125]

Kinetic molecular theory first made a name for itself when scientists attempted to explain and predict the properties of gases and, in particular, how those properties changed with varying temperature and pressure. The idea emerged that the particles of matter within a gas (atoms or molecules) undergo a serious amount of motion as a result of the kinetic energy within them. [Pg.149]

A gas may be defined as a homogeneous fluid of low density and low viscosity, which has neither independent shape nor Volume but expands to fill completely the vessel in which it is contained. The properties of gases differ considerably from the properties of liquids, mainly because the molecules in gases are much farther apart than molecules in liquids. For instance, a change in pressure has a much greater effect on the density of a gas than of a liquid. [Pg.90]

None of the equations discussed so far in this chapter adequately represents the properties of gases over the ranges of temperature and pressure of interest to the petroleum engineer. These equations are given here to illustrate the various semitheoretical schemes researchers have used in an attempt to modify the ideal gas equation of state to describe real gas properties. [Pg.133]

Unlike solids and liquids, different gases show remarkably similar physical behavior regardless of their chemical makeup. Helium and fluorine, for example, are vastly different in their chemical properties yet are almost identical in much of their physical behavior. Numerous observations made in the late 1600s showed that the physical properties of any gas can be defined by four variables pressure (P), temperature (T), volume (V), and amount, or number of moles in). The specific relationships among these four variables are called the gas laws, and a gas whose behavior follows the laws exactly is called an ideal gas. [Pg.346]

These two equations are applicable to mixtures of ideal gases as well as to pure gases, provided n is taken to be the total number of moles of gas. However, we must consider how the properties of the gas mixture depend upon the composition of the gas mixture and upon the properties of the pure gases. In particular, we must define the Dalton s pressures, the partial pressures, and the Amagat volumes. Dalton s law states that each individual gas in a mixture of ideal gases at a given temperature and volume acts as if it were alone in the same volume and at the same temperature. Thus, from Equation (7.1) we have... [Pg.136]

The following table gives the properties of common gas chromatographic carrier gases. These properties are those used most often in designing separation and optimizing detector performance. The density values are determined at CPC and 0.101 MPa (760 torr).1 The thermal conductivity values, X, are determined at 48.9°C (120°F).1 The viscosity values are determined at the temperatures listed and at 0.101 MPa (760 torr).1 The heat capacity (constant pressure) values are determined at 15°C and 0.101 MPa (750 torr).2... [Pg.10]

The liquid-gas equilibrium line terminates at a point known as the critical point. The temperature and pressure that define the critical point are known as the critical temperature and the critical pressure. For example, nitrous oxide has a critical temperature of 36°C and a critical pressure of 72.45 bar (1051 psi). When the temperature and pressure exceed these critical values, the system becomes a supercritical fluid. Supercritical fluids have the flow properties of gases but densities similar to liquids, and supercritical fluids have no surface tension. Therefore, supercritical fluids are terrific solvents. For example, supercritical carbon dioxide is an excellent solvent for extracting caffeine from coffee without resorting to more toxic organic solvents like dichloromethane. [Pg.188]

Every chemistry student is familiar with the ideal gas equation PV = nRT. It turns out that this equation is a logical consequence of some basic assumptions about the nature of gases. These simple assumptions are the basis of the kinetic theory of gases, which shows that the collisions of individual molecules against the walls of a container creates pressure. This theory has been spectacularly successful in predicting the macroscopic properties of gases, yet it really uses little more than Newton s laws and the statistical properties discussed in the preceding chapters. [Pg.149]

The ideal gas law has been used in many examples in earlier chapters, and some of the important physical properties of gases (the one-dimensional velocity distribution, average speed, and diffusion) were presented in Chapter 4. This chapter puts all of these results into a more comprehensive framework. For example, in Section 7.3 we work out how the diffusion constant scales with pressure and temperature, and we explore corrections to the ideal gas law. [Pg.149]

From the earliest days of quantitative inquiry, scientists have sought to uncover the mathematical relationships that describe natural phenomena, including the properties of gases. Because there are four fundamental properties of a gas, namely, P, T, V, and n, discovering the relationship between any two requires that the other two properties be kept constant. Some of the earliest quantitative studies of gases were reported in the mid-1600s by British chemist Robert Boyle, who found that for a fixed amount of a gas at a specific temperature (i.e., constant n and T), the volume was inversely proportional to the applied pressure. This V-P relationship, known as Boyle s law, is represented as... [Pg.140]

Alveolar wash-in This term refers to the replacement of the normal lung gases with the inspired anesthetic mixture. The time required for this process is directly proportional to the functional residual capacity of the lung, and inversely proportional to the ventilatory rate it is independent of the physical properties of the gas. Once the partial pressure builds within the lung, anesthetic uptake from the lung begins. [Pg.122]


See other pages where Properties of Gases Gas Pressure is mentioned: [Pg.195]    [Pg.195]    [Pg.197]    [Pg.199]    [Pg.232]    [Pg.195]    [Pg.195]    [Pg.197]    [Pg.199]    [Pg.232]    [Pg.61]    [Pg.664]    [Pg.252]    [Pg.633]    [Pg.143]    [Pg.315]    [Pg.262]    [Pg.286]    [Pg.270]    [Pg.531]    [Pg.656]    [Pg.90]    [Pg.1082]    [Pg.4]    [Pg.496]    [Pg.692]    [Pg.90]    [Pg.115]   


SEARCH



Gas properties

Pressure of gas

Properties of gases

© 2024 chempedia.info