エンタルピー: 状態量の一つ

${\displaystyle H=U+pV}$ 

${\displaystyle H(S,p,N)=U(S,V(S,p,N),N)+pV(S,p,N)}$ 

${\displaystyle W=p_{\text{ex}}\Delta V}$ 

${\displaystyle q=\Delta U+W=\Delta U+p_{\text{ex}}\Delta V}$ 

${\displaystyle \Delta H=\Delta (U+p_{\text{ex}}V)=\Delta U+p_{\text{ex}}\Delta V}$ 

${\displaystyle q=\Delta H}$ 

${\displaystyle Q=-q=-\Delta H}$ 

${\displaystyle \left({\frac {\partial H}{\partial T}}\right)_{p}=C_{p}(T,p)}$ 

${\displaystyle \left({\frac {\partial H}{\partial p}}\right)_{T}=V(T,p)-T\left({\frac {\partial V}{\partial T}}\right)_{p}}$ 

${\displaystyle \left({\frac {\partial H}{\partial p}}\right)_{T}=TV\left({\frac {1}{T}}-\alpha \right)}$ 

${\displaystyle V(T,p)={\frac {RT}{p}}+B(T)+O(p^{1})}$ 

${\displaystyle \left({\frac {\partial H}{\partial p}}\right)_{T}=B(T)-T{\frac {dB}{dT}}+O(p^{1})}$ 

${\displaystyle H(T,p)=H_{0}(T)+p\left[B(T)-T{\frac {dB}{dT}}\right]+O(p^{2})}$ 

${\displaystyle H_{0}(T)=\lim _{p\to 0}H(T,p)}$