Volume mass, pressure, temperature

Type of storage media Volume (g/lt) Mass (%) Pressure (MPa) Temperature (K)... 

To calculate the properties of each gas in a mixture of gases To calculate molar masses from mass data along with pressure, volume, temperature data, and to use the molar masses thus calculated to enable calculation of molecular formulas from empirical formulas... 

Calculation of the entropy of a perfect gas. The calculation of w in terms of quantities which can be measured experimentally (pressure, volume, temperature), and of the number and mass of the molecules, is accompanied in the general case by very serious difl culties. For a perfect monatomic gas Boltzmann has succeeded in solving the problem, thus calculating the entropy S. For a perfect monatomic gas he deduces from equation (1) the expression t... 

The properties of gases that are most easily observed are the relationships among pressure, volume, temperature, and mass. If you have ever inflated a balloon, baked a cake, or slept on an air mattress, you have observed how these properties are related. Because the laws of gases were developed from the study of their properties and behavior, it is now possible to predict the physical behavior of gases by the application of these laws. 

If a system with an artificially and permanently expanded interlayer space was to be modeled (in order to model an external surface, for example), all calculations were performed under NVT (constant mass, volume, and temperature) conditions. In certain other situations such as those described below, the artificially expanded systems were first allowed to equilibrate under NVT conditions and subsequently subjected to NPT (constant mass, pressure, and temperature) conditions, whereupon the separated layers spontaneously reannealed, thereby restoring the equilibrium interlayer spacing characteristic of that particular system. 

A 5.00-g sample of gas is contained in a 2.51-L vessel at 25°C and 1. 10 atm pressure. The gas contains 81.8% carbon and the rest hydrogen, (a) What can be calculated from the pressure-volume-temperature data (b) What can be calculated from the mass and the answer to part (a) (c) What can be calculated from the percent composition data (d) What can be calculated from the answers to parts (b) and (c) ... 

Considering the absolute accuracies to which pressure, volume, temperature and mass may be practically measured, hydrogen may safely be taken to be ideal above room temperature and at pressures below a few bar. At higher pressures or lower temperatures, the need to account for its non-ideality becomes apparent. Perhaps the simplest approach, and the one used exclusively here, is to define the compressibility, Z, of the gas by ... 

Of the three states of aggregation, only the gaseous state allows a comparatively simple quantitative description. For the present we shall restrict this description to the relations among such properties as mass, pressure, volume, and temperature. We shall assume that the system is in equilibrium so that the values of the properties do not change with time, so long as the external constraints on the system are not altered. 

Next, we study the relationship among pressure, volume, temperature, and amount of a gas in terms of various gas laws. We wiU see that these laws can be summarized by the ideal gas equation, which can be used to calculate the density or molar mass of a gas. (5.3 and 5.4)... 

Certain properties are necessary to describe a system completely. These are macroscopic properties such as pressure, volume, temperature, mass etc. These defining properties of a system are referred to as state properties or state variables of a system. For a homogenous system, for example, whose composition is already fixed, only two of the variables, say pressure and temperature need to be specified. The third variable, volume in this case, gets automatically fixed as these variables are inter-related by the relation PV = RT. The two variables to define the system may be chosen suitably and are called independent variables. The third variable is known as the dependent variable. 

Macroscopic properties such as pressure, volume, temperature, composition are needed to describe a system. These are called state variables or state properties of a system. Properties whose values depend on the amount of the substance or the size of the substance are called extensive properties (Mass, volume, energy etc.)... 

The Joule-Thomson effect occurs without the transfer of heat. Temperature is affected by the relationship between volume, mass, pressure, and temperature. Rapid expansion of a gas from high to low pressure results in a temperature drop. This principle was employed by Dutch physicist Heike Kamerlingh Onnes to liquefy helium in 1908 and is useful in home refrigerators and air conditioners. 

The mass fraction, W, is 0 the internal energy, /, is Ig and the specific volume, V, is Vg. The pressure, volume, temperature, and energy values of the detonation products are computed using the BKW code described in Appendix E. They are fitted by the method of least squares to Equations (A.7)-(A.9). A gamma-law gas also may be fitted to these equations using the GLAW code included on the CD-ROM. 

The type of system most commonly encountered in chemical engineering apphcations has the primary characteristic variables pressure, volume, temperature and compositiom Such systems are made up of fluids, liquid or gas, and are called PVT systems. The conservation laws concern the accumulation rate of mass, amount of components, energy and momentum of such a system. The variables depend on the extent of a system and are therefore called extensive variables. Extensive properties are additive. When mirltiple systerrrs are combined to a new system, the new value of the variable will be the sum of the initial ones. In contrast, temperature, pressttre, specific volirme and composition are conditions imposed upon or exhibited by the system. These are intensive variables. When systems are combined to a new system, the new value of the variable will be the equilibrium value of the initial ones. 

Phase behaviour describes the phase or phases in which a mass of fluid exists at given conditions of pressure, volume (the inverse of the density) and temperature (PVT). The simplest way to start to understand this relationship is by considering a single component, say water, and looking at just two of the variables, say pressure and temperature. 

A general prerequisite for the existence of a stable interface between two phases is that the free energy of formation of the interface be positive were it negative or zero, fluctuations would lead to complete dispersion of one phase in another. As implied, thermodynamics constitutes an important discipline within the general subject. It is one in which surface area joins the usual extensive quantities of mass and volume and in which surface tension and surface composition join the usual intensive quantities of pressure, temperature, and bulk composition. The thermodynamic functions of free energy, enthalpy and entropy can be defined for an interface as well as for a bulk portion of matter. Chapters II and ni are based on a rich history of thermodynamic studies of the liquid interface. The phase behavior of liquid films enters in Chapter IV, and the electrical potential and charge are added as thermodynamic variables in Chapter V. 

The relationship between pressure p, volume V, mass m, and temperature T is given by the equation of state ... 

Ideal gas obeys the equation of state PV = MRT or P/p = MRT, where P denotes the pressure, V the volume, p the density, M the mass, T the temperature of the gas, and R the gas constant per unit mass independent of pressure and temperature. In most cases the ideal gas laws are sufficient to describe the flow within 5% of actual conditions. When the perfect gas laws do not apply, the gas compressibility factor Z can be introduced ... 

We denoted the mass of dry air in a volume V as that is, p, - w,/Vj, and the mass of water vapor in V as m, that is, pp = mp/Yp. In practical calculations we usually handle volume flow volume flow is known in the suction inlet of a fan when the operating point of the fan is defined. Volume flow q, expressing the total air flow or the combined volume flow of water vapor and dry air, is not constant in various parts of the duct, because the pressure and temperature can vary. Therefore in technical calculations dealing with humid air, materia flows are treated as mass flows. Also, while the humidity can vary, the basic quantity is dry air mass flow w,(kg d.a./s). If, for instance, we know the volume flow q,. of a fan, the dry air mass flow through the fan is... 

Avogadro s Hypothesis States that Equal volumes of different gases at the same pressure and temperature contain the same number of molecules. Hence, the volume occupied by any gas whose mass is numerically equal to its molecular weight is a constant quantity. 

Density The measure of the amount of mass in a unit volume. The density of a gas is a function of its pressure and temperature, It can be determined by using the ideal gas laws. 

This equadon indicates diat for a given mass of a specific gas, PV/T has a consumt value. Since, at the same temperature and pressure, volume and mass must be directly proportional, diis statement may be e.xtended to... 

The state of a system containing a constant amount of material depends upon a few variables, e.g. pressure p, volume V, temperature T. For a given mass of pure substance the volume can be expressed solely as a function of pressure and temperature... 

We see that, for a given pressure and temperature, the greater the molar mass of the gas, the greater its density. Equation 10 also shows that, at constant temperature, the density of a gas increases with pressure. When a gas is compressed, its density increases because the same number of molecules are confined in a smaller volume. Similarly, heating a gas that is free to expand at constant pressure increases the volume occupied by the gas and therefore reduces its density. The effect of temperature on density is the principle behind hot-air balloons the hot air inside the envelope of the balloon has a lower density than that of the surrounding cool air. Equation 10 is also the basis for using density measurements to determine the molar mass of a gas or vapor. 

The ideal gas equation can be combined with the mole-mass relation to find the molar mass of an unknown gas PV = nRT (ideal gas equation) and n — (mole-mass relation) if we know the pressure, volume, and temperature of a gas sample, we can use this information to calculate how many moles are... 

Because moles are the currency of chemistry, all stoichiometric computations require amounts in moles. In the real world, we measure mass, volume, temperature, and pressure. With the ideal gas equation, our catalog of relationships for mole conversion is complete. Table lists three equations, each of which applies to a particular category of chemical substances. 

C05-0091. Ammonia is produced industrially by reacting N2 with H2 at elevated pressure and temperature in the presence of a catalyst N2 + H2 NH3 (unbalanced) Assuming 100% yield, what mass of ammonia would be produced from a 1 1 mole ratio mixture in a reactor that has a volume of 8.75 X 10 L, under a total pressure of 275 atm at T = 455 °C ... 

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