Question

1. using the graph above, describe the connections between the temperature of a solvent and the solubility of a solute that is a solid. what would happen if a hot solution with a lot of solid in it cooled down?

Explanation:

Step1: Analyze the graph trend

The graph shows solubility (y - axis, grams per 100g \(H_2O\)) vs. temperature (x - axis, \(^\circ C\)) for solid solutes (\(NH_4Cl\), \(KCl\), \(NaCl\), \(KClO_3\)). All lines have a positive slope, meaning as temperature (\(T\)) increases, solubility (\(S\)) of these solid solutes increases. Mathematically, for each solid, \(S\) and \(T\) have a direct relationship (positive correlation).

Step2: Predict cooling effect

A hot solution with a high amount of dissolved solid (near saturation at high \(T\)) is a supersaturated or saturated solution at high \(T\). When cooled, since solubility decreases with decreasing \(T\) (from the graph's trend), the solution can no longer hold all the dissolved solid. So, the excess solid will precipitate out (crystallize) as the solution cools, because the solubility limit at the lower temperature is lower than the amount of solute present.

Answer:

For solid solutes (from the graph), solubility increases with increasing solvent temperature (all solid solute solubility curves have positive slopes, showing a direct relationship between temperature and solubility). If a hot solution with a lot of dissolved solid cools down, the solubility of the solid solute decreases, so the excess solute (that the cooler solvent can no longer dissolve) will precipitate (crystallize) out of the solution.