What is the Constant Volume Specific Heat for Diatomic Gases?

In summary, the speaker is asking for help locating specific heat constants with constant volume, and the responder suggests looking at thermodynamic property tables for the column with Cv. They also mention that Cp is the specific heat at constant pressure and that Cp-Cv=R, where R is a constant. They then provide an equation for finding Cp and mention that for monoatomic gases, f=3 and for diatomic gases, f=5 (or 7 at high temperatures).
  • #1
melanie
1
0
Just trying to locate specific heat constants with constant volume (not pressure), any ideas where to find this?
 
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  • #2
If you have a thermodynamic set of property tables it would be in the column with Cv (v should be a subscript) if you are looking at Cp that is the specific heat at constant pressure. They should be fairly close in most non-extreme conditions so becareful what your looking at
 
  • #3
[itex]C_p[/itex] : Specific Heat at constant pressure
[itex]C_v[/itex] : Specific Heat at constant volume

Also [itex]C_p - C_v = R[/itex]

[itex]\frac {C_p}{C_v} = lamda[/itex]

where lamda = [itex]1 + \frac {2}{f}[/itex]

Where f=degrees of freedon

for monoatomic gas , f=3
for diatomic gas , f=3

You can solve for two expressions at the top to get Cp

BJ
 
  • #4
One correction to Dr.Brain's post. f for diatomic gases is 5
 
  • #5
quark said:
One correction to Dr.Brain's post. f for diatomic gases is 5
And that's only at around room temperature's where the vibrational degree of freedom is absent. At high temperatures, f will be 7 for diatomic gases.
 

What is constant volume specific heat?

Constant volume specific heat, also known as isochoric specific heat, is the amount of heat required to raise the temperature of a unit mass of a substance by one degree at constant volume.

How is constant volume specific heat different from constant pressure specific heat?

Constant volume specific heat is measured at constant volume, while constant pressure specific heat is measured at constant pressure. This means that the volume of the substance remains constant during the measurement of constant volume specific heat, while the pressure remains constant during the measurement of constant pressure specific heat.

What is the formula for calculating constant volume specific heat?

The formula for calculating constant volume specific heat is: cV = Q / (m * ΔT), where cV is the constant volume specific heat, Q is the amount of heat added, m is the mass of the substance, and ΔT is the change in temperature.

What are some real-world applications of constant volume specific heat?

Constant volume specific heat is used in thermodynamics to calculate the amount of heat needed to raise the temperature of a substance in a closed system. It is also used in the design of engines and other heat transfer devices. Additionally, it is useful in understanding the behavior of gases, such as in the ideal gas law.

How is constant volume specific heat experimentally determined?

Constant volume specific heat can be experimentally determined by measuring the change in temperature of a substance at constant volume while adding a known amount of heat. This process can be repeated multiple times to obtain an average value of cV. Other methods, such as differential scanning calorimetry, can also be used to determine cV.

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