Name_________________________________________
Period_____
Practice Solubility Curves
Directions: Use the graph to answer the following questions. Use the correct units (check the axis).
For most substances, solubility increases as temperature increases. As discussed earlier, more solute can be dissolved
at higher temperatures; can you find any exceptions on the graph?
Example: Find the curve for KCIO3.
At 30°C approximately 10g of KCIO3 will dissolve in 100g of water. If the temperature is increased to 80°C,
approximately 40g of the substance will dissolve in 100g (or 100mL or 100cm3) of water. (Density H2O = 1 g/mL and
1mL = 1cm3)
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On a solubility curve, the lines indicate the concentration of a saturated solution – the maximum
amount of solute that will dissolve at that specific temperature.
Values on the graph beneath a curve represent unsaturated solutions; more solute could be
dissolved at that temperature.
A supersaturated solution would have a value above the solubility curve.
1. What mass of solute will dissolve in 100.mL of water at the following temperatures?
a. KNO3 at 70°C =
b. NaCI at 100°C=
c. NH4CI at 90°C=
d.
Which of the above three substances is most soluble in water at 15°C
e.
Which of the above three substances is least soluble in water at 40°C?
2. Label the following solutions as saturated or unsaturated. If unsaturated, write how much more solute can
be dissolved in the solution.
Solution
Saturated or Unsaturated
If unsaturated, how much
more can be dissolved?
a solution that contains 70g of
NaNO3 at 30°C (in 100mL H2O)
a solution that contains 50g of
NH4CI at 50°C (in 100 mL H2O)
a solution that contains 385g of
KI at 0°C (in 550 mL H2O)
a solution that contains 15g of
KCIO3 at 50°C (in 75 mL H2O)
3. What is the solubility of KCl at 5°C?
4. What is the solubility of KCl at 25°C?
5. How many grams of Ce2(SO4)3 will dissolve in 50.0g of water at 10°C?
6. How many grams of Ce2(SO4)3 will dissolve in 275g of water at 50°C?
7. At 90°C, 80.g of KCI is dissolved in 100.g of water. Is this solution saturated, unsaturated or
supersaturated? Explain.
8. A mass of 200.g of NaNO3 is dissolved in 200.g of water at 80°C.
a. Is the solution saturated or unsaturated?
b. As the solution is cooled, at what temperature should solid first appear in the solution? Explain.
9. A mass of 80. g of KNO3 is dissolved in 100. g of water at 50°C. The solution is heated to 70°C. How
many more grams of potassium nitrate must be added to make the solution saturated? Explain your
reasoning.
10. Based on your notes and what you see in the graph, how do you think the solubility curve for a GAS
would look? Explain.
11. A saturated solution of ammonium chloride is made with 100. g water at 90oC. How much ammonium
chloride would crystallize out if the solution is cooled to 50oC
More Practice Solubility Curves
Based on the solubility curve decide whether each of the following is:
A: unsaturated, B: saturated, C: supersaturated, or D: not enough information given. * assume it is dissolved *
1) 50 g KCl in 100 g of water at 90˚C.
5) 69 g KNO3 in 50 g of water at 70˚C. _____
2) 50 g KCl in 100 g of water at 60˚C.
6) 25 g KNO3 in 100 g of water.
3) 50 g KNO3 in 100 g of water at 60˚C.
7) 25 g NaCl in 100 g of water.
4) 50 g KNO3 in 25 g of water at 60˚C.
8) 150 g of KCl in 375 g of water at 20˚C.
9) How many grams of KCl cannot dissolve if you add 60.g KCl to 100.0 g of water at 65˚C? __________
10) What temperature would be required to get 85 g of KNO3 to dissolve in 100.0 g of water?
11) How many grams of NaNO3 can be dissolved in 50.0 g of water at 50.0˚C?
12) What mass of KClO3 can be dissolved in 200.0 g of water at 15.0˚C?
13) How much NH3 can be dissolved in 14.3 g of water at 69.0˚C?
14) How many grams of water will it take to dissolve 28.0 g NH4Cl at 60.0˚C?
15) How much water is needed to dissolve 46.6 g of KNO3 at 28˚C?
16) What temperature would be required to get 71.0 g of KCl to dissolve in 156 g of water?
17) What is the percent KClO3 in a solution that is saturated at 61˚C?
18) What temperature is required to make a 50.0% KNO3 solution?
19) What temperature is required to make a 20.0% KClO3 solution?_______