Question #71391

1 Answer
Mar 27, 2017

Answer:

No, the solution is not saturated.

Explanation:

Your tool of choice here will be the solubility graph of potassium nitrate, #"KNO"_3#, which looks like this

www.nakka-rocketry.net

The curve shows you the amount of potassium nitrate than can be dissolved per #"100 mL"# of water at various temperatures in order to create a saturated solution of potassium nitrate.

For the sake of simplicity, let's assume that the graph shows the solubility of the salt per #"100 g"# of water.

Now, if you draw a vertical line starting from #90^@"C"#, you will notice that it intersects the curve at approximately #"200 g"# of potassium nitrate per #"100 g"# of water.

This represents the solubility of the salt at this temperature. In other words, you can only hope to dissolve #"200 g"# of potassium nitrate for every #"100 g"# of water at #90^@"C"#.

Your solution contains #"30 g"# of potassium nitrate per #"100 g"# of water at this temperature, so it will not be saturated because you can dissolve an additional

#"200 g"color(white)(.) - color(white)(.)"30 g" = "170 g KNO"_3#

for every #"100 g"# of water at this temperature. You can thus say that the solution is unsaturated.