Gas Behavior at Standard Conditions

To better understand the factors that influence gas behavior, chemists use a set of standard conditions called standard temperature and pressure (STP)  

Under these conditions, the volume of 1 mol of an ideal gas is called the standard molar volume  

Number of gas particles = 6.022x1023 Number of gas particles = 6.022x1023 Number of gas particles = 6.022x1023 

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The Relationship Between Volume and Amount Avogadro s Law 156 Gas Behavior at Standard Conditions 156 The Ideal Gas Law 157 Solving Gas Law Problems 158... 

The sulfur dioxide enters the reactor with an initial concentration of 10% by volume, the remainder being air. At the exit of the first bed, the temperature is 620°C. Assume ideal gas behavior, the reactor operates at 1 bar and R = 8.3145 kJ-Kr -lonoD1. Assume air to be 21% 02 and 79% N2. Thermodynamic data at standard conditions at 298.15 K are given in Table 6.186. 

It can be assumed that the gas mixture follows ideal gas behavior and that the kilogram molar mass of a gas occupies 22.4 m3 at standard conditions of 0°C and 1 atm (1.013 bar)... 

The gas flow also depends on the temperature and on the pressure. Assuming an ideal gas behavior of the carrier gas it can be calculated from the flow rate at standard conditions ... 

Catalytic activity is measured by determining the behavior of the catalyst in laboratory-scale equipment at standardized conditions for each test method, measuring especially the production of gas and distillate, although carbon deposition and other results are also noted in most methods. Of the numerous methods (at least 14), the Houdry Cat. A, Jersey D + L, and UOP activity rating are probably the most widely used. The approximate relation between these is indicated in Table 21-12. 

The standard state for a pure liquid or solid is taken to be the substance in that state of aggregation at a pressure of 1 bar. This same standard state is also used for liquid mixtures of those components that exist as a liquid at the conditions of the mixture. Such substances are sometimes referred to as liquids that may act as a solvent. For substances that exist only as a solid or a gas in the pure component state at the temperature of the mixture, sometimes referred to as substances that can act only as a solute, the situation is more complicated, and standard states based on Henry s law may be used. In this case the pressure is again fixed at 1 bar, and thermal properties such as the standard-state enthalpy and heat capacity are based on the properties of the substance in the solvent at infinite dilution, but the standard-state Gibbs energy and entropy are based on a hypothetical state.of unit concentration (either unit molality or unit mole fraction, depending on the form of Henry s law used), with the standard-state fugacity at these conditions extrapolated from infinite-dilution behavior in the solvent, as shown in Fig. 9.1-3a and b. Therefore just as for a gas where the ideal gas state at 1 bar is a hypothetical state, the standard state of a substance that can only behave as a solute is a hypothetical state. However, one important characteristic of the solute standard state is that the properties depend strongly upon the solvent. used. Therefore, the standard-state properties are a function of the temperature, the solute, and the solvent. This can lead to difficulties when a mixed solvent is used. 

Whereas there is no universally accepted specification for marketed natural gas, standards addressed in the United States are Hsted in Table 6 (8). In addition to these specifications, the combustion behavior of natural gases is frequently characteri2ed by several parameters that aid in assessing the influence of compositional variations on the performance of a gas burner or burner configuration. The parameters of flash-back and blow-off limits help to define the operational limits of a burner with respect to flow rates. The yeUow-tip index helps to define the conditions under which components of the natural gas do not undergo complete combustion, and the characteristic blue flame of natural gas burners begins to show yellow at the flame tip. These... 

Should we regard 407.1 2.0 kJ mol-1 as the final value for the enthalpy of reaction 2.13 under the experimental conditions Recall that the starting assumption was p = 1 bar and the standard state conditions refer to the ideal gases at that pressure or to the real gases at zero pressure. The ideal gas model (or the ideal gas equation) describes very well the behavior of most gases at 1 bar, so it is... 

We are most familiar with the three standard phases of matter the solid, liquid, and gaseous states (Figure 1.2) however, the idea of a phase can be much broader. In fact, there are many different states of matter that have been defined in-between the solid and gas phases, and we will learn about a number of them in this book. Soft materials often exhibit complex phase behavior with many different phases possible under different conditions (i.e., temperature, composition, pressure, etc.). Understanding the structure and properties of these phases and how we can move between them is at the heart of soft matter science. 

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