The value of Cp

[Sue Xu 2K]

In 9.7 I believe we have to use the equation S = nCp lnT1/T2. Are we always given the value of Cp?

[SantanaRodriguezDis1G]

on the test we should be given the value of Cp and you only use Cp if it explicitly says constants pressure.

[kaushalrao2H]

Cp for ideal gases is 4R. Cv for ideal gases is 3R. When in doubt, remember that Cp = Cv + R

[Josh Moy 1H]

Cp of ideal gases is 5/2(R) and Cv is 3/2(R)

[Naomi Jennings 2H]

Cp for ideal gases is 4R. Cv for ideal gases is 3R. When in doubt, remember that Cp = Cv + R

I thought for an ideal gas Cp is (5/2)R and Cv is (3/2)R?

[Kyle Sheu 1C]

Yup--for a monatomic ideal gas, Cv = 3/2R and Cp = Cv + R = 5/2R

Note that for diatomic gases, it gets a little tricker (e.g. for N2, Cv = 5/2R) due to more rotational degrees of freedom

[Wayland Leung]

So we only use the C value when there is a constant pressure value and use the R constant value when the pressure isnt constant?

[Joanne Guan 1B]

The C_p and C_v values can be found on page 281 in the textbook. C_p is the heat capacity of the system at constant pressure while C_v is the heat capacity at constant volume. R is the ideal gas constant, and you would typically use R in the form 8.3145 J*K^-1*mol^-1 for these calculations.

[AtreyiMitra2L]

On the test, you will be given the table of values that will help you solve for cP