Mayers Relation of specific heat

[Amith2006]

Sir,
Two expressions for relation between specific heats are given and it is asked to say which one is right. They are:
1)Cp – Cv = R
2)Cp – Cv = R/J
Which of the 2 is right? Here Cp and Cv are the specific heat of gas at constant pressure and volume respectively. R is universal gas constant and J is the mechanical equivalent of heat.

 

[maverick280857]

Sir,
Two expressions for relation between specific heats are given and it is asked to say which one is right. They are:
1)Cp – Cv = R
2)Cp – Cv = R/J
Which of the 2 is right? Here Cp and Cv are the specific heat of gas at constant pressure and volume respectively. R is universal gas constant and J is the mechanical equivalent of heat.

Both ...depends on what units you use.

 

[kyle8921]

It is important to note that both expressions are correct and can be used in different scenarios. The first expression, Cp – Cv = R, is known as Mayer's relation and is applicable for ideal gases. This relation shows the difference between the specific heat of a gas at constant pressure (Cp) and constant volume (Cv) is equal to the universal gas constant (R). This relation is derived from the first law of thermodynamics and is often used in thermodynamic calculations.

The second expression, Cp – Cv = R/J, is known as the modified Mayer's relation and is applicable for non-ideal gases. This relation takes into account the mechanical equivalent of heat (J) and is used to calculate the difference between the specific heats of a gas at constant pressure and constant volume for non-ideal gases. This relation is derived from the first law of thermodynamics and the Joule-Thomson coefficient.

Therefore, it is not accurate to say that one expression is "right" and the other is "wrong". Both relations are valid and have their own uses in different scenarios. It is important to understand the assumptions and limitations of each relation before using them in calculations.