confusion on using Cp and Cv

[Catherine Bubser 2C]

Do we use Cp when we are told the pressure is constant or when we are told the volume is constant? I know it means "constant pressure", but if anyone has an example of a question that directly points to us using Cp versus Cv could you please respond with it?

[Kiran Singh 3A]

We use Cp when told that the pressure is constant and Cv when told that the volume is constant. The C part is referring to the heat capacity, and the p and v are referring to what is being held constant. Hope this clears up some confusion. Problem 4.C.3 in the textbook uses both Cp and Cv, so you might want to check it out.

[Jessica Katz]

To add onto the relationship between Cp and Cv, Cp = Cv + R so the other can be found when given one. The usage of either Cp and Cv will depend on which is constant like people mentioned above.

[MinjooPark_3I]

What I like to do is I use the one that is mentioned in the problem. If the question is focusing on volume I use Cp and when it is focusing on pressure I use Cp. Although we may be given the initial and final volumes/pressures in the question, when we calculate using the Cv of Cp, we assume the volume/pressure change already occurred and that they are constant.

[Brandon Pham 1H]

Cp = Heat capacity at constant pressure
Cv = Heat capacity at constant volume

The problem will most likely give you one of these values

[Madison Wong 3H]

Cp is the heat capacity at constant pressure, and Cv is the heat capacity at constant volume. They are related by the equation Cp = Cv + R.

[Lauren Sarigumba 1K]

Cp is the heat capacity at constant pressure while Cv is the heat capacity at constant volume.

[Gabriel Nitro 1E]

Hi,

Yes! Recall, C refers to the heat capacity, or the amount of heat to raise the temperature of a substance by 1 unit of temperature. The subscript "P" or "V" is indicative of what variable we are assuming is constant.

If it is "C_p," then it is the heat capacity at constant pressure. If it is "C_v," then it is the heat capacity at constant volume.

Hope this helps! :)

[Cora Chun 2D]

Hi, Cp is when pressure is constant and Cv is when volume is constant. You can tell by looking at the subscript next to the "C". Hope this helps!

[Hasan Mirza 3F]

Cp is used with constant pressure and Cv is used with constant volume.

[Jason Knight - 1F]

Cp is the heat capacity value for constant pressure and Cv is the heat capacity value for constant volume. We will typically use these values when the problem explicitly states when the system is under conditions of constant pressure or value, but keep an eye out if ideal gas conditions are also described.

[Mursall M 2A]

Cp is used when it is mentioned that there is constant pressure, and Cv is used when it is mentioned that there is constant volume!

[Tobie Jessup 2E]

Cp is used under conditions of constant pressure and Cv is used under conditions of constant volume.

[Vanessa Perez]

We use Cp when pressure is constant and Cv when volume is constant. Remember the difference between diatomic and monatomic

[RyanKopeikin_2I]

Cp is used for conditions of constant pressure, and Cv is used for conditions of constant volume.

[RyanKopeikin_2I]

Cp is used for conditions of constant pressure, and Cv is used for conditions of constant volume.

[Brian_Wu_3B]

Usually you find theneed to use Cp or Cv when looking at changes in entropy when temperature varies. When temperature varies, the problem usually keeps either pressure or volume constant. If pressure is constant, then Cp is used. If volume is constant, then Cv is used.

[Katelynn Shaheen 2C]

Cp is the heat capacity when pressure is constant and Cv is the heat capacity when volume is constant. They are used in the equation Cp=Cv+R.

[Britney Tran IJ]

Cp is for conditions with constant pressure, and Cv is for conditions with constant volume

[Nina Fukui 2J]

Cp is for when the pressure is constant and Cv is for when the volume is constant. They're usually given and if the question mentions that the gas is ideal, then the values can be found on the formula sheet

[Navdha Sharma 3J]

C_p is the heat capacity at constant pressure while C_v is the heat capacity at constant volume.
Also, C_p = C_v + R

[BoparaiAdeshsurjit2F]

The C means heat capacity

[Nan_Guan_1L]

Cp=Cv + R. Cp refers to the conditions under constant pressure, Cv refers to constant volume. If you take a look at the textbook problems you’ll find abundant examples

[DPatel_2L]

Cp is heat capacity at a constant pressure while Cv is heat capacity at constant volume.

[Jacob Schwarz-Discussion 3I]

The relationship between Cp and Cv is that Cp=Cv+R