Gases temperature/pressure/volume

Fig. 11-8 Change in gas volume with pressure then temperature...

If you have a gas at a certain set of volume/temperature/pressure conditions and at least some of the conditions change, then you will probably be using the combined gas equation. If moles of gas are involved, the ideal gas equation will probably be necessary... 

The isotherm (plot of pressure versus volume) at the temperature Tc plays a special role in the theory of the states of matter. An isotherm behaves in accordance with the gas laws slightly below T. At certain pressure, a liquid condenses from gaseous state and is distinguishable from it by the presence of a visible interface. If, however, the compression takes place at a surface separating two phases does not appear and the volumes at each end of the horizontal part of the isotherm have merged to a single point, critical point of the gas. The temperature, pressure, and molar volume at the critical point are called the critical temperature T, critical pressure P, and critical molar volume of the substance respectively. Collectively,... 

In the following series of impingers, tars are absorbed in the solvent at a temperature of -20°C. A backup residual tar adsorber can optionally be used as a safety filter after the impinger train. The volume, temperature, pressure, and gas flow rate through the equipment are measured after the impinger bottles. 

Remember that gas volumes and pressures are proportional to temperature only if the temperature is expressed in kelvins. 

The gas laws deal with the following variables— the number of gas particles, temperature, pressure, and volume. Which of these are held constant in Boyle s law, in Charles s law, and in the combined gas law ... 

This may be easily shown as follows Consider r gram of gas volume v, pressure, temperature T We have the relation... 

This simply shows that there is a physical relationship between different quantities that one can measure in a gas system, so that gas pressure can be expressed as a function of gas volume, temperature and number of moles, n. In general, some relationships come from the specific properties of a material and some follow from physical laws that are independent of the material (such as the laws of thermodynamics). There are two different kinds of thermodynamic variables intensive variables (those that do not depend on the size and amount of the system, like temperature, pressure, density, electrostatic potential, electric field, magnetic field and molar properties) and extensive variables (those that scale linearly with the size and amount of the system, like mass, volume, number of molecules, internal energy, enthalpy and entropy). Extensive variables are additive whereas intensive variables are not. 

This law turned out, however, to be not exactly true. The German-French chemist Henri Victor Re-gnault (1810-78) made many careful measurements of gas volumes and pressures in the midnineteenth century and showed that, especially as pressure was raised or temperature was lowered, gases did not quite follow Boyle s law. 

The residual volume is obtained by applying the definition of residual to volume. Using Us = RT/P for the ideal-gas volume at pressure P and temperature T, the residual volume is... 

If you take Bojde s Law, Charles s Law, Gay-Lussac s Law, and Avogadro s Law and throw them into a blender, turn the blender on high for a minute, and then pull them out, you get the ideal gas equation — a way of working in volume, temperature, pressure, and amount. The ideal gas equation has the following form ... 

Four variables define the physical behavior of an ideal gas volume V), pressure Pj, temperature (T), and amount (number of moles, n). Most simple gases display nearly ideal behavior at ordinary temperatures and pressures. Boyle s, Charles s, and Avo-gadro s laws relate volume to pressure, to temperature, and to amount of gas, respectively. At STP (0°C and 1 atm), 1 md of an ideal gas occupies 22.4 L. The ideal gas law incorporates the individual gas laws into one equation PV = nRT, where R is the universal gas constant. 

When the calculation involves a change in volume, temperature, pressure, or amount of gas, it is more convenient to use one of the individual gas laws. When the calculation does not involve a change in any of these quantities, the ideal gas equation is usually more useful. 

Despite the dominance of Newton s view, some people followed the kinetic interpretation. In 1738, Daniel Bernoulli, a Swiss mathematician and physicist, gave a quantitative explanation of Boyle s law using the kinetic interpretation. He even suggested that molecules move faster at high temperatures, in order to explain Amontons s experiments on the temperature dependence of gas volume and pressure. However, Bernoulli s paper attracted little notice. A similar kinetic interpretation of gases was submitted for publication to the Royal Society of London in 1848 by John James Waterston. His paper was rejected as nothing but nonsense. ... 

In 1662, Robert Boyle discovered that gas pressure and volume are related mathematically. The observations of Boyle and others led to the development of the gas laws. The gas laws are simple mathematioal relationships among the volume, temperature, pressure, and amount of a gas. 

Peng-Robinson (PR) equation of state An equation of state used to predict the behaviour of real gases based on the van der Waals equation of state, ft describes the variation of molar gas volume and pressure with temperature for many substances in a cubic equation as ... 

The initial temperature of a gas condensate lies between the critical temperature and the cricondotherm. The fluid therefore exists at initial conditions in the reservoir as a gas, but on pressure depletion the dew point line is reached, at which point liquids condense in the reservoir. As can be seen from Figure 5.22, the volume percentage of liquids is low, typically insufficient for the saturation of the liquid in the pore space to reach the critical saturation beyond which the liquid phase becomes mobile. These... 

TABLE 2.19 Factors for Reducing Gas Volumes to Normal (Standard) Temperature and Pressure (760 mmHg)... 

A number of potential sources of error must be taken into account. In the volumetric method the following items need attention (a) constancy of the level of liquid nitrogen (b) depth of immersion of the sample bulb ( S cm) (c) temperature of sample (monitoring with vapour pressure thermometer close to sample bulb) (d) purity of adsorptive (preferably 99-9 per cent) (e) temperature of gas volumes (doser, dead space), controlled to 01 C. 

AH gas volumes at standard temperature and pressure. To convert to cal, divide by 4.184. 

The pressure—volume—temperature (PVT) behavior of many natural gas mixtures can be represented over wide ranges of temperatures and pressures by the relationship... 

Gas purification processes fall into three categories the removal of gaseous impurities, the removal of particulate impurities, and ultrafine cleaning. The extra expense of the last process is only justified by the nature of the subsequent operations or the need to produce a pure gas stream. Because there are many variables in gas treating, several factors must be considered (/) the types and concentrations of contaminants in the gas (2) the degree of contaminant removal desired (J) the selectivity of acid gas removal required (4) the temperature, pressure, volume, and composition of the gas to be processed (5) the carbon dioxide-to-hydrogen sulfide ratio in the gas and (6) the desirabiUty of sulfur recovery on account of process economics or environmental issues. 

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