Second Law of Thermodynamics: Entropy

"Entropy is a measure of the disorder of a system. Entropy also describes how much energy is *not* available to do work. The more disordered a system and higher the entropy, the less of a system's energy is available to do work." "The equation for the change in entropy, $\Delta S$, is $\Delta S = \frac{Q}{T}$, where *Q* is the heat that transfers energy during a process, and *T* is the absolute temperature at which the process takes place." "The second law of thermodynamics states that *the total entropy of a system either increases or remains constant in any spontaneous process; it never decreases.* An important implication of this law is that heat transfers energy spontaneously from higher- to lower-temperature objects, but never spontaneously in the reverse direction." "Based on this equation, we see that $\Delta S_{\text{syst}}$ can be negative as long as $\Delta S_{\text{envir}}$ is positive and greater in magnitude." (referring to $\Delta S_{\text{tot}} = \Delta S_{\text{syst}} + \Delta S_{\text{envir}} > 0$) "Find the increase in entropy of 1.00 kg of ice that is originally at 0 °C and melts to form water at 0 °C. … $\Delta S = \frac{Q}{T} = \frac{3.34 \times 10^5\text{ J}}{273\text{ K}} = 1.22 \times 10^3\text{ J/K}.$"