# Ideal Gas Heat Capacity Regression Coefficients

1. May 15, 2013

### cjc0117

I'm trying to find a comprehensive list of the empirical coefficients to be used in the following equation for calculating ideal gas constant pressure heat capacities:

$\frac{c^{IG}_P}{R}=A+BT+CT^{2}+DT^{-2}+ET^{3}$
(Eqn. 1)​

cPIG is the ideal gas constant pressure specific heat capacity; R is the universal gas constant; A,B,C,D,E are the empirical constants; T is temperature

I've found empirical constants for the Shomate equation (similar to Eqn. 1 above except that T is replaced with t=T/1000) for a limited number of chemicals, but I can't find this data in a table.

I've tried following links to NIST-JANAF thermochemical tables, and I've tried looking in the API Technical Data Book to no avail (it may be there but I just can't find it amongst all the other data).

"The Properties of Liquids and Gases" by Reid et al. has a comprehensive list of empirical constant but they use an equation in this form instead:

$\frac{c^{IG}_P}{R}=A'+B'T+C'T^{2}+D'T^{3}+E'T^{4}$
(Eqn. 2)​

I suppose I could fit data derived from Eqn. 2 to Eqn. 1 if I need to. I just want to see if I can find references that use Eqn. 1.

The table at this link, http://www.personal.utulsa.edu/~geoffrey-price/Courses/ChE7023/HeatCapacity-HeatOfFormation.pdf, and the book "Engineering and Chemical Thermodynamics" by Koretsky has empirical constants for Eqn. 1. That's all I've been able to find.

Does anybody know of any other references I could use? Thanks.

Last edited: May 15, 2013