Dear research colleagues,
when I calculate the entropy S° of crystalline materials from heat capacity measurements (Cp) from (almost) 0 K to 298 K by integrating Cp/T, I have "the feeling" to end up with a quite precise/reliable value of S° for the respective material. However, when I compare such a value with other ones in literature (eg. obtained from vapor pressure measurements), I frequently find a significant discrepancy between them, most of the time that the value from the Cp-measurement is quite lower (>20 J/(mol*K) than the other values.
Now my question is, if my feeling is "right" that the values obtained from Cp-measurements are actually more trustworthy, or if there are some problems with this way of determining the entropy, that I'm not aware of?
Thanks for your help!
There are several things you may not be considering. 1) this isn't an ideal gas so Cp isn't enough in itself; 2) crystals have significant structural entropy; 3) most substances have an entropy of formation; 4) different texts and calculations often have different reference points and these don't mix. I suggest you get this book. It is free tomorrow (9/29) https://read.amazon.com/kp/embed?asin=B07Q5L1CHT&preview=newtab&linkCode=kpe&ref_=cm_sw_r_kb_dp_9B0F20GYBXBZD4FWNDN2
And this book on thermochemical reactions is free on Saturday (10/1) https://read.amazon.com/kp/embed?asin=B07SW9LWTS&preview=newtab&linkCode=kpe&ref_=cm_sw_r_kb_dp_B8KR3PGH3G59Q37E8G90
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