Gas laws empirical

All gases under moderate conditions behave quite simply with respect to pressure, temperature, volume, and molar amount. By holding any two of these physical properties constant, it is possible to show a simple relationship between the other two. The discovery of these quantitative relationships, the empirical gas laws, occurred from the mid-seventeenth to the mid-nineteenth century. 

One characteristic property of a gas is its compressibility—its ability to be squeezed into a smaller volume by the application of pressure. By comparison, liquids and solids are relatively incompressible. The compressibility of gases was first studied 

The volume of the gas at normal atmospheric pressure (760 mmHg) is 100 mL.When the pressure is doubled by adding 760 mm of mercury, the volume is halved (to 50 mL).Tripling the pressure decreases the volume to one-third of the original (to 33 mL). 

Boyle s law can also be expressed in the form of an equation. Putting pressure and volume on the same side of the equation, you can write 

Model of gas pressure-volume relationship at a constant temperature 

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The work of the empirical gas laws made it possible to formulate a state function to completely describe the state of a gas under a given set of conditions. This is called the ideal gas law, which has the form ... 

Under what conditions should you use the ideal gas law, and when should you use the empirical gas laws ... 

The ideal gas law is most useful when the problem describes only a single state (temperature, pressure, and/or volume). The empirical gas laws are useful for changing the state of a gas (F, n, V, and/or T change). 

Other empirical gas laws exist (Berthelot,35 Dieterici,36 Beattie37-Bridgman,38 etc.), but the search for a simple, yet generally valid, gas law for all gases at all conditions of temperature, pressure, and volume has failed. Engineers must thus rely on tabular data (e.g., steam tables) rather than on a master equation. One intuitively useful gas equation is Kamerlingh Onnes 39 virial equation (a fancy term for a power series) ... 

Pressure is defined as force/area measured in atm, bar, pascal, and torn The empirical gas laws of Boyle, Charles, and Avogadro combine to give the ideal gas law PV = nRT. 

Table 5.4 lists the molar volumes of several gases. The values agree within about 2% of the value expected from the empirical gas laws (the ideal gas value). We will discuss the reason for the deviations from this value at the end of this chapter, in the... 

In the previous section, we discussed the empirical gas laws. Here we will show that these laws can be combined into one equation, called the ideal gas equation. Earlier we combined Boyle s law and Charles s law into the equation... 

Using the empirical gas laws Given an initial volume occupied by a gas, calculate the final volume wheu the pressure changes at fixed temperatnre (EXAMPLE 5.2) when the temperature changes at fixed pressure (EXAMPLE 53) and when both pressure and temperature change (EXAMPLE 5j ). 

Deriving empirical gas laws from the ideal gas law Starting from the ideal gas law, derive the relationship between any two variables. (EXAMPLE 5.5)... 

The ideal gas law relates four variables. An empirical gas law relates two variables, assuming the other two are constant. How many empirical gas laws can be obtained Give statements of each. 

Deriving the Ideal Gas Equation from the Empirical Gas Laws... 

Although none of the empirical gas laws focuses on the relationship between n and P explicitly, we can rearrange the ideal gas equation to show that n is directly proportional to P at constant V and T ... 

Kinetic molecular theory can be used to explain the compressibdity of gases and the empirical gas laws. 

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