Question

Potassium sulfate has a solubility of 15 g/100 g water at 40°C. A solution is prepared by adding 47 g of potassium sulfate to 150 g of water, carefully heating the solution, and cooling it to 40°C. A homogeneous solution is obtained. Answer the following questions to determine whether the solution is saturated, unsaturated, or supersaturated. How many grams of potassium sulfate would dissolve in 100 g of water to make a saturated solution?

Answer 1

The final homogenous solution, after cooling it to 40°C, will contain 47 g of potassium sulfate disolved in 150 g of water, so you can calculate the amount disolved per 100 g of water in this way:

[47 g of solute / 150 g of water] * 100 g of g of water = 31.33 grams of solute in 100 g of water.

So, when you compare with the solutiblity, 15 g of solute / 100 g of water, you realize that the solution has more solute dissolved with means that it is supersaturated.

To make a saturated solution, 15 grams of potassium sulfate would dissolve in 100 g of water.