A sample of potassium nitrate (49g) is dissolved in 101g of water at 100°C, with precautions taken to avoid evaporation of any water. The solution is cooled to 30°C and no precipitate is observed. The solution is ________.

A. Hydrated
B. Supersaturated
C. Unsaturated
D. Placated
E. Saturated

I know the difference between the choices, but I don't know how to use that info to answer the question. Help please? Thanks!

I can tell you this much. This is a lousy question. The solution COULD be saturated but there is no way to know with the information listed. It IS hydrated for sure. If not saturated, then the solution is unsaturated. So the correct answers are A and either B or C depending. I suspect the question is looking for C to be the correct answer just from the way the problem is stated.

I missed a point here. It could also be supersaturated. I suggest you look up the solubility of KNO3 at 30o C, then you will know.

supersaturated

To determine the nature of the solution, we need to compare the amount of solute (potassium nitrate) dissolved in the solvent (water) at different temperatures.

First, let's calculate the solubility of potassium nitrate in water at 100°C. The solubility of potassium nitrate increases with temperature, so we can assume that at 100°C, potassium nitrate is fully dissolved in water.

Now, let's compare the amount of solute dissolved in the two scenarios:

1. At 100°C: We have 49g of potassium nitrate dissolved in 101g of water. The total mass of the solution is 49g + 101g = 150g.

2. At 30°C: We still have 49g of potassium nitrate, but the mass of water available has decreased to 101g. The total mass of the solution remains the same at 150g.

Now, let's compare the amount of potassium nitrate dissolved in the two scenarios:

1. At 100°C: The mass of potassium nitrate is 49g.

2. At 30°C: The mass of potassium nitrate is still 49g.

Since the amount of potassium nitrate dissolved is the same at both temperatures, we can conclude that the solution at 30°C is still fully saturated. In other words, it is saturated with potassium nitrate.

Therefore, the answer to the question is:

E. Saturated

Explanation: By comparing the amount of solute dissolved at different temperatures, we can determine the nature of the solution (saturated, unsaturated, supersaturated) based on its solubility.