Ideal Gas Equation: Pressure not Proportional to Moles

In summary, the ideal gas equation is a mathematical relationship that describes the behavior of ideal gases. It is written as PV = nRT and includes the variables of pressure, volume, number of moles, gas constant, and temperature. The pressure in an ideal gas is not directly proportional to the number of moles, as volume and temperature also play a role. This equation is a simplified model for ideal gases and is most accurate for monatomic gases at low pressures and high temperatures. The units of the gas constant, R, depend on the units used for the other variables. While the ideal gas equation can be used for all gases, it is most accurate for monatomic gases and less accurate for gases with stronger intermolecular forces.
  • #1
bluejay27
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how is pressure not proportional to the number of moles?
 
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  • #2
bluejay27 said:
how is pressure not proportional to the number of moles?
Who says it's not?
 
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Likes Chestermiller
  • #3
Young and Freedman page 591-592 in the ideal gas equation section. The author does not seem to include the relationship between the number of moles and pressure.
 
  • #4
For those of us who don't have the book handy... What exactly do they say?
 
  • #5
But... PV=nRT... So P is proportional to n, if you keep everything else stable...
 

FAQ: Ideal Gas Equation: Pressure not Proportional to Moles

1. What is the ideal gas equation?

The ideal gas equation, also known as the general gas equation, is a mathematical relationship that describes the behavior of an ideal gas under different conditions. It is written as PV = nRT, where P is the pressure of the gas, V is the volume, n is the number of moles, R is the gas constant, and T is the temperature in Kelvin.

2. Why is pressure not proportional to the number of moles in the ideal gas equation?

In an ideal gas, the pressure is not directly proportional to the number of moles because the volume and temperature also play a role in determining the pressure. As the number of moles increases, the volume of the gas also increases, resulting in a decrease in pressure. Similarly, an increase in temperature would result in an increase in pressure.

3. How does the ideal gas equation relate to real gases?

The ideal gas equation is a simplified model that applies to ideal gases, which do not exist in reality. Real gases have intermolecular forces and occupy a non-zero volume, which affects their behavior. However, under certain conditions of low pressure and high temperature, real gases can behave similarly to ideal gases, making the ideal gas equation a useful approximation.

4. What are the units of the gas constant in the ideal gas equation?

The units of the gas constant, R, depend on the units used for pressure, volume, and temperature in the ideal gas equation. In SI units, R has a value of 8.314 J/mol·K. However, when using different units, such as atm for pressure and L for volume, the value of R would be different. It is important to use consistent units when using the ideal gas equation.

5. Can the ideal gas equation be used for all gases?

The ideal gas equation can be used for all gases, but it is most accurate for monatomic gases, such as helium, neon, and argon, at low pressures and high temperatures. For gases with stronger intermolecular forces, such as water vapor and carbon dioxide, the ideal gas equation is less accurate and other equations, such as the van der Waals equation, may be used.

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