Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Mayer's relation

  1. Jan 2, 2007 #1
    1. The problem statement, all variables and given/known data
    1) According to Mayer’s equation,
    C(p) – C(v) = R ------------ (1)
    Where C(p) = specific heat at constant pressure
    C(v) = specific heat at constant volume
    R = Universal gas constant
    But sometimes the above equation is used in the following way,
    C(p) – C(v) = R/J ---------------- (2)
    Where C(p) = gram molecular specific heat of the gas at constant pressure
    C(v) = gram molecular specific heat of the gas at constant volume
    R = Universal gas constant
    J = Mechanical equivalent of heat



    2. Relevant equations



    3. The attempt at a solution

    What are the units of C(p) & C(v) in equation(1)?
     
  2. jcsd
  3. Jan 3, 2007 #2
    because the units on the two sides of the equation must match in order for the equation to be valid, the units of C_p and C_v must be the same as the units for the universal gas constant R.
     
  4. Jan 3, 2007 #3
    If we divide R by J then the unit of R will be Calorie/mole.Kelvin. So by doing this we change the unit of R from work unit to heat unit, isn't it?
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook