### 7th edition 4C.3

Posted: **Wed Jan 30, 2019 8:29 pm**

by **Daisylookinland**

This question, you have to use the formulas: qp=nCpDeltaT and qv=nCvDeltaT, but in the solution book they substitute Cp for (5/2R) and Cv for (3/2R). Can someone explain these substitutions?

### Re: 7th edition 4C.3

Posted: **Thu Jan 31, 2019 4:54 pm**

by **Venya Vaddi 1L**

The textbook shows the derivation of Cp,m=Cv,m+R.

For a monatomic gas, Cv,m=delta U/delta T, which gives 3/2*R. (this derivation is also shown in the book on page 265 of the seventh edition in detail).

Using this result for Cv,m and the above formula, Cp,m is 5/2*R.