Is the Van der Waals Gas Equation More Accurate Than the Ideal Gas Equation?

In summary, the conversation discusses the differences between the real and ideal pressure and volume in the van der Waals equation. The speaker suggests checking both equations for different cases and confirms that the real volume is indeed smaller than the ideal volume. They then question why the real volume can be bigger than the ideal volume, but later clarify that this is due to the ideal gas equation not accounting for molecule size.
  • #1
requal
8
0
Just wondering, for van der waals equation, the real pressure is smaller than the ideal pressure and the real volume is smaller than the ideal volume?
 
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  • #2
Check - calculate P&V for several cases using both ideal gas equation and VdV equation.
 
  • #3
Okay I found out that the real volume is indeed less than the ideal volume, but I don't get how the real volume is bigger than the ideal volume? I thought it would be the other way around because molecular volume becomes significant at high pressures meaning that gases have less free space to move around (because some of the space is taken up by the gas molecules themselves), and hence the real volume would be lower than the ideal volume? No?
 
  • #4
requal said:
Okay I found out that the real volume is indeed less than the ideal volume, but I don't get how the real volume is bigger than the ideal volume?

This is a little bit convoluted and I have a feeling you are contradicting yourself - volume is less but you don't understand how it is bigger?

Ideal gas ignores molecule size, so at high pressures it theoretically compresses to zero, real volume is much larger than that.
 
  • #5


Yes, that is correct. The van der Waals equation takes into account the real volume of gas particles and the attractive forces between them, resulting in a lower pressure and volume compared to the ideal gas equation. This is important in understanding the behavior of real gases, especially at high pressures and low temperatures.
 

1. What is the Van der Waals gas equation?

The Van der Waals gas equation is an equation that describes the behavior of real gases, taking into account the volume and attractive forces between gas molecules. It is an improvement upon the ideal gas law, which assumes that gas molecules have no volume and do not interact with each other.

2. Who developed the Van der Waals gas equation?

The Van der Waals gas equation was developed by Dutch physicist Johannes Diderik van der Waals in 1873. He received the Nobel Prize in Physics in 1910 for his work on the equation and his other contributions to the study of gases.

3. What are the variables in the Van der Waals gas equation?

The variables in the Van der Waals gas equation are pressure (P), volume (V), temperature (T), and the parameters a and b, which account for the attractive forces between gas molecules and the volume occupied by the gas molecules, respectively.

4. How does the Van der Waals gas equation differ from the ideal gas law?

The ideal gas law assumes that gas molecules have no volume and do not interact with each other, whereas the Van der Waals gas equation takes into account the volume and attractive forces between gas molecules. This makes it more accurate for describing the behavior of real gases, especially at high pressures and low temperatures.

5. What is the significance of the Van der Waals gas equation?

The Van der Waals gas equation is significant because it provides a more accurate description of the behavior of real gases, taking into account their volume and attractive forces. It is also a foundational equation in the study of thermodynamics and has applications in various fields such as chemistry, physics, and engineering.

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