A pan full of hot salt water, NaCl(aq), is cooled and NaCl(s) precipitates. Explain why this happens.
Chloride ions are more strongly attracted to the metal in the pan than the sodium ions at low temperatures.
As the vapor pressure of the solution decreases the solubility of the salt goes down.
As the temperature decreases the solubility of the salt goes down and the salt in excess settles out as a precipitate.
As the temperature decreases the solubility of the salt goes up and the salt in excess dissolves.
is the answer Chloride ions are more strongly attracted to the metal in the pan than the sodium ions at low temperatures?
I think that's hogwash.
then is this the correct answer
As the temperature decreases the solubility of the salt goes down and the salt in excess settles out as a precipitate.
That's much better, although the solubility of NaCl is not much higher at 100 C than it is at 0 C.
http://www.kentchemistry.com/links/Kinetics/SolubilityCurves.htm
The correct explanation is:
As the temperature decreases, the solubility of the salt (NaCl) in water decreases. This means that at lower temperatures, less NaCl can be dissolved in water. When a pan full of hot salt water (NaCl(aq)) is cooled down, the temperature decrease causes the solubility of the salt to go down. As a result, the excess NaCl in the solution becomes insoluble and forms solid particles, or precipitates, of NaCl(s).
The reason for this behavior lies in the attractive forces between the water molecules (solvent) and the NaCl ions (solute). When NaCl is dissolved in water, it dissociates into chloride ions (Cl-) and sodium ions (Na+). At higher temperatures, the water molecules have more kinetic energy and move more rapidly, leading to stronger collisions with the NaCl ions. These strong collisions help keep the ions in solution, preventing them from recombining to form solid NaCl.
However, as the temperature decreases, the kinetic energy of the water molecules decreases. This means that the collisions between the water molecules and the NaCl ions become less frequent and energetic. The reduced collisions weaken the hold of the water molecules on the Na+ and Cl- ions, making it easier for them to come back together to form solid NaCl. This process is called precipitation.
Therefore, the cooling of the pan full of hot salt water causes the solubility of NaCl to decrease, leading to the formation of NaCl(s) precipitate as the excess salt settles out of solution.