A sample of potassium nitrate (49.0 g) is dissolved in 101 g of water at 100 °C, with precautions taken to avoid evaporation of any water. The solution is cooled to 30.0 °C and a small amount of precipitate is observed. This solution is .
A) hydrated
B) unsaturated
C) saturated
D) placated
E) supersaturated

Question

Quizplus · Accepted Answer

At 100 °C, potassium nitrate is completely soluble in water, indicating that the solution was unsaturated to begin with. When the solution was cooled to 30.0 °C, the solubility of potassium nitrate decreased, causing it to come out of the solution and form a precipitate. This means that the solution was saturated at 30.0 °C, as it contains the maximum amount of potassium nitrate that can dissolve in it at that temperature. Therefore, the correct answer is C.

A Sample of Potassium Nitrate (49