The formulas for [[Entropy|entropy]] are similar to those previously mentioned. $s_2−s_1=\ln⁡\left(\dfrac{T_2}{T_1}\right)\sum_{i=1}^kc_iC_{p0,i}−\ln\left(\dfrac{P_2}{P_1}\right)\sum_{i=1}^kc_iR_i$