The first law applied to a closed system undergoing a
reversible process states that
dQ = du + pdu
According to second law,
ds = dQ
T rev.
Combining these equations, we get
Tds = du + pdv
6.lo
0r du = Tds - pdu
g may also be put in terms of
The properties h, fand
T, s, p and u as follows : +t vdp
du
dh = + pdv + vdp = Tds
Helmholtz free energy function,
df =du -Tds -sdT (6.12)
-pdu - sdT
reversible process states that
dQ = du + pdu
According to second law,
ds = dQ
T rev.
Combining these equations, we get
Tds = du + pdv
6.lo
0r du = Tds - pdu
g may also be put in terms of
The properties h, fand
T, s, p and u as follows : +t vdp
du
dh = + pdv + vdp = Tds
Helmholtz free energy function,
df =du -Tds -sdT (6.12)
-pdu - sdT
