What are the limitations of the Ideal Gas Law?

In summary, the conversation discusses various gas laws and their limitations. The Ideal gas law, PV=nRT, assumes no intermolecular forces and negligible volume of molecules, which is true at low pressures. However, in cases where this is not true, the Van der Waals equation is used instead.
  • #1
optrix
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I've been looking at Charles law, Boyles law, the Pressure law, and the Ideal gas law, PV=nRT. I want to know, what limitations are there to the gas law? Basically, why aren't real gasses ideal, when isn't it possible to use the ideal gas law, and in such a case, what else do you have to use instead? Thanks alot.
 
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  • #2
For ideal gases, we are assuming that there are no intermolecular forces and that the molecules themselves take up no volume. This is quite true at low pressures, because the spacing between the molecules is so large that they rarely collide. Also low pressure usually means that there is little of them or that the volume of the container is very large, so the space taken up by the actual molecules is negligible.

If you are dealing with cases where this is not true, you use the Van der Waals equation:
http://en.wikipedia.org/wiki/Van_der_Waals_equation
 
  • #3
Thanks for the help!
 

1. What is the ideal gas law and what are its limitations?

The ideal gas law, also known as the general gas equation, is a mathematical relationship that describes the behavior of gases under various conditions. It states that the pressure, volume, and temperature of an ideal gas are related by the equation PV = nRT, where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature. However, this law has some limitations, including assuming that the gas particles have no volume, there is no intermolecular attraction, and the particles move in a random motion.

2. What are the assumptions made by the ideal gas law?

The ideal gas law makes several assumptions, including that the gas particles have no volume, there is no intermolecular attraction, and the particles move in a random motion. These assumptions are not always true for real gases, and therefore, the ideal gas law may not accurately predict their behavior.

3. Can the ideal gas law be used for all gases?

No, the ideal gas law is only applicable to ideal gases, which are theoretical gases that follow the assumptions of the law. Real gases, on the other hand, have varying levels of intermolecular attraction and volume, and therefore, the ideal gas law may not accurately describe their behavior.

4. What are the units for the ideal gas constant in the ideal gas law?

The ideal gas constant, represented by the symbol R, has a value of 8.314 J/mol·K. Its units are derived from the other variables in the ideal gas law equation, with pressure in Pascals (Pa), volume in cubic meters (m3), temperature in Kelvin (K), and the number of moles being unitless. Therefore, the units for the ideal gas constant can be written as (Pa·m3)/(mol·K).

5. What are the limitations of using the ideal gas law in real-life situations?

While the ideal gas law is a useful tool for understanding the behavior of gases, it has some limitations when applied to real-life situations. These limitations include not accounting for deviations from ideal behavior, such as at high pressures or low temperatures, and not considering the effects of gas mixtures or chemical reactions. Therefore, it is important to use caution when applying the ideal gas law to real-world scenarios and to consider other factors that may affect gas behavior.

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