If a bowl of salt water is left in the sun long enough for the water to evaporate a layer of salt crystals will be left in the bottom of the bowl. Salt crystals are more ordered than dissolved ions.

How does the increase or decrease in entropy relate to the second law of thermondynamics?

What happened to all the water? What about its entropy?

The increase or decrease in entropy relates to the second law of thermodynamics. The second law states that the total entropy of a closed system will always increase or remain constant over time. Entropy is a measure of the disorder or randomness in a system.

In the case of the bowl of salt water left in the sun, the water evaporates as a result of the heat from the sun. Evaporation is a process where water molecules gain enough energy to break free from the liquid phase and enter the gas phase. As the water molecules transition from the liquid phase to the gas phase, the system becomes more disordered, resulting in an increase in entropy.

When the water evaporates, the dissolved salt ions are left behind. As the water molecules leave, the salt ions come closer together, leading to the formation of salt crystals. Since the salt crystals have a highly ordered structure, they have a lower entropy compared to the dissolved salt ions in the water.

So, in summary, the water molecules gain energy from the sun and transition from the liquid phase to the gas phase, leading to an increase in entropy. The dissolved salt ions, on the other hand, become more ordered as they form salt crystals, resulting in a decrease in entropy.