Final answer:
A solution with 40 g of NaCl in 100 g of water at 80°C exceeds the solubility limit, therefore it is a supersaturated solution. Supersaturation is achieved by dissolving more solute at a higher temperature and then allowing the solution to cool.
Step-by-step explanation:
When discussing the solubility of a solute in a solvent, we often refer to terms like saturated, unsaturated, and supersaturated. A saturated solution contains the maximum amount of solute that is capable of dissolving in the solvent at a given temperature. At 80°C, the saturation point for sodium chloride (NaCl) in water (H₂O) is approximately 36 g of NaCl in 100 g of water. Given that the student's solution contains 40 g of NaCl in 100 g of water at 80°C, this solution would be considered supersaturated, since it exceeds the solubility limit at that temperature.
Conditions for a supersaturated solution are created when more solute is dissolved than what would normally be possible at a particular temperature, typically by heating the solvent and allowing it to cool slowly. Supersaturated solutions are unstable and can precipitate the excess solute when triggered, such as by dropping a crystal of the solute into the solution.