# Ds equation for ideal gases

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1. Dec 15, 2016

### Bohr1227

ds=cvdT/T + R dv/v. I saw this equation in my text book, but I do not see how it can be correct. By using cv, they assume that the volume is held constant. For me it does not make sense to use it when you have dv in the equation because this would be equal to 0.

Are there any assumptions I have missed? Is there something I am missing in my thinking process?

Thanks!