How much CuSO4 5H2O crystallizes out?

Hi,

Since the solubility of KNO3 at 0 Celsius was not provided, i'm using one of the number on Google : ~12g KNO3/100H20  (http://www.thomas.k12.ga.us/userfiles/212/Classes/41899/SolubilityGraphsanswers.pdf 1st graph)

2a) Total volume of your solution is 11.5 + 10 = 21.5mL.   
your KNO3 remain in the solution : 9/100 = x/21.5    x = 2.58 g KNO3

2b) KNO3 crystallizes out: 25 - 2.58 = 22.42g

2c) Since solubility of CuSO4*5H2O is not provided....my source says 31.6g/100mL (https://pubchem.ncbi.nlm.nih.gov/compound/Copper_II__sulfate_pentahydrate#section=Solubility)
Volume of your solution is still 21.5mL
CuSO4*5H2O in the solution is 31.6/100 = x/21.5  x = 6.794 g CuSO4*5H2O
CuSO4*5H2O crystallizes out would be 0, since you only have 2g in the beginning

2d) I am assuming that you just recovered the crystal in part 1d and nothing else was done.
From 2b, we have 22.42g of KNO3 crystallizes out. Therefore, %KNO3 recovered = (22.42/25)*100 = 89.68%

Please note that all of these calculations were based on the solubilities found on google, make sure you adjust the number accordingly based on your experiment or what is provided in your lab manual.

Hope this helps,

The heat drives off the water of crystallization leaving gray anhydrous CuSO4.
The heat causes blue copper sulfate (also known as hydrated copper sulfate) to decompose forming anhydrous copper sulfate and water. Anhydrous copper sulfate formed is white in color.