What is the Difference Between Critical Constant and Van der Waals Constant?
🆚 Go to Comparative Table 🆚The critical constant and Van der Waals constant are terms related to the behavior of substances under different temperature, pressure, and density conditions. Here are the main differences between them:
- Critical Constant: These are the critical temperature, critical pressure, or critical density of a substance. The critical point is the temperature and pressure at which the liquid and vapor phases coexist. Critical constants are specific to the substance and are used to describe the behavior of the substance at its critical point.
- Van der Waals Constant: Van der Waals constants are constant values used in the Van der Waals equation, which is a modified version of the ideal gas law. This equation can be used for both ideal gases and real gases, unlike the ideal gas law, which can only be used for ideal gases. The Van der Waals equation is used to describe the behavior of a substance at any point, not just at its critical point.
In summary, critical constants are specific to the substance and describe its behavior at its critical point, while Van der Waals constants are used in an equation that describes the behavior of a substance at any point. Critical constants can be derived from Van der Waals constants.
Comparative Table: Critical Constant vs Van der Waals Constant
The critical constant and Van der Waals constant are related to the behavior of substances under different temperature, pressure, and density conditions. Here is a table summarizing the differences between the two:
| Parameter | Critical Constant | Van der Waals Constant |
|---|---|---|
| Definition | Values for a substance at its critical point (temperature and pressure at which liquid and vapor phases coexist) | Values for a substance at any point, used in the Van der Waals equation (a modified version of the ideal gas law) |
| Description | Relates to the critical point where the liquid and vapor phases of a substance coexist | Constants (a and b) in the Van der Waals equation, which describe the intermolecular forces and the volume occupied by gas particles |
| Equation | Not explicitly mentioned, but related to the principle of corresponding states | $$P + a \frac{n^2}{V^2} = RT$$ (where P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is temperature) |
| Application | Used to describe the behavior of a substance at its critical point | Used to describe the behavior of ideal and real gases, including non-ideal behavior due to molecular size and intermolecular forces |
In summary, critical constants are specific to the critical point of a substance, where the liquid and vapor phases coexist, while Van der Waals constants are used in the Van der Waals equation to describe the behavior of gases, including non-ideal behavior due to molecular size and intermolecular forces.
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