更改

According to the Clausius equality, for a reversible process

According to the Clausius equality, for a reversible process

With this we can only obtain the difference of entropy by integrating the above formula. To obtain the absolute value, we need the third law of thermodynamics, which states that S = 0 at absolute zero for perfect crystals.

With this we can only obtain the difference of entropy by integrating the above formula. To obtain the absolute value, we need the third law of thermodynamics, which states that S = 0 at absolute zero for perfect crystals.

据此，只有对上述公式进行积分，才能得到熵的差值。为了获得绝对值，我们需要<font color="#FFD700">'''热力学第三定律 Third Law of Thermodynamics''' </font>，它指出<font color="#FFD700">'''绝对零度 Absolute Zero''' </font>下完美晶体的 ''S'' = 0。

据此，只有对上述公式进行积分，才能得到熵的差值。为了获得绝对值，我们需要'''热力学第三定律 Third Law of Thermodynamics'''，它指出'''绝对零度 Absolute Zero'''下完美晶体的 ''S'' = 0。

Notice that if the process is an adiabatic process, then <math>\delta Q=0</math>, so <math>\Delta S\ge 0</math>.

Notice that if the process is an adiabatic process, then <math>\delta Q=0</math>, so <math>\Delta S\ge 0</math>.

注意，若该过程是一个<font color="#FFD700">'''绝热过程 Adiabatic Process'''</font>，则<math>\delta Q=0</math>，故<math>\Delta S\ge 0</math>。

注意，若该过程是一个'''绝热过程 Adiabatic Process'''，则<math>\delta Q=0</math>，故<math>\Delta S\ge 0</math>。

===Energy, available useful work===

===Energy, available useful work===