Solubility graph and solutions CW 1
1. What is the solubility of potassium nitrate (KNO3) in 100.0 g of water at
60.0°C?
2. What is the minimum temperature needed to dissolve 100 g of NaNO3 in
100.0 g of water?
3. What is the solubility of NaNO3 in 100 g of water at 60.0°C?
4. How much more KClO3 can be dissolved at 80°C than at 30°C?
5. How much more NaCl will dissolve at 100°C than at 50°C?
6. How much more NaNO3 will dissolve in 100 g of water at 30°C than KNO3?
7. A solution contains 50.0 g of NH4Cl in 100.0 g of water at 50°C. Is this
solution saturated or unsaturated?
8. If 140 g of KNO3 is mixed with 100.0 g of water at 40°C, how much will not
dissolve?
9. 70.0 g of solute is added to 100 g of water at 30°C. All 70.0 g of solute
dissolves. According to your solubility chart, what possible compounds are
capable of dissolving 70.0 g at 30°C? (Hint: there are only two)
10. A saturated solution of NH4Cl at 50°C is cooled to 30°C. What will happen?
11. If a saturated solution of KNO3 at 40°C is heated to 70°C, how much more
could be dissolved?
12. A solution contains 30 g of KCl in 100.0 g of water at 80°C. Is this solution
saturated or unsaturated?
The following do not require info from the graph above:
13. What is the molarity of a solution that contains 275 g of NaCl in 955 mL
solution? (molar mass of NaCl = 58.44 g/mol)
275 / 58.44 = 4.71 mol NaCl
14. How would you take a saturated solution and make it unsaturated?
15. How many moles of HCl are present in 1.30 L of a 0.63 M HCl solution?
(molar mass of HCl = 36.46 g/mol)
16. If 220 mL of solvent is added to a 1.2 L 3.0 M solution, determine the
concentration of the final solution.
17. A NaOH solution contains 0.70 mol of NaOH, and its concentration is 0.345 M.
What is the volume?
18. Describe how to dilute 250 ml of a 3.0 M solution to a 1.0 M solution
19. How would you find out if a solution at 50°C was saturated?
20. How many milliliters of a 0.251 M solution contain 2.50 g of NaCl? (molar
mass of NaCl = 58.44 g/mol)
Solubility graph and solutions CW 1
Answers
1. What is the solubility of potassium nitrate (KNO3) in 100.0 g of water at
60.0°C?
100 g
(start at 60°C, trace up to KNO3 line, then over to mass scale on Y-axis)
2. What is the minimum temperature needed to dissolve 100 g of NaNO3 in
100.0 g of water?
35°C
3. What is the solubility of NaNO3 in 100 g of water at 60.0°C?
124 g ( ± 2)
4. How much more KClO3 can be dissolved at 80°C than at 30°C? 30 g
(difference in solubility at each temperature, 40 – 10, ± 2 on each)
5. How much more NaCl will dissolve at 100°C than at 50°C?
(40 – 38, ± 1 on each)
2g
6. How much more NaNO3 will dissolve in 100 g of water at 30°C than KNO3?
96 – 46 = 50 g
(solubility of NaNO3 – KNO3 at that temperature)
7. A solution contains 50.0 g of NH4Cl in 100.0 g of water at 50°C. Is this
solution saturated or unsaturated?
Saturated
(The solubility is 50 g, so if you put in 50 g then it’s full)
8. If 140 g of KNO3 is mixed with 100.0 g of water at 40°C, how much will not
dissolve?
140 – 60 = 80 g will not dissolve
9. 70.0 g of solute is added to 100 g of water at 30°C. All 70.0 g of solute
dissolves. According to your solubility chart, what possible compounds are
capable of dissolving 70.0 g at 30°C? (Hint: there are only two)
KI and NaNO3 (only ones with solubility higher than 70 g at that temp)
10. A saturated solution of NH4Cl at 50°C is cooled to 30°C. What will happen?
50 – 41 = 9 grams will precipitate out of solution.
(that’s how much the solubility drops, answer must be worded this way)
11. If a saturated solution of KNO3 at 40°C is heated to 70°C, how much more
could be dissolved?
130 – 60 = 70 g more (or close to it)
12. A solution contains 30 g of KCl in 100.0 g of water at 80°C. Is this solution
saturated or unsaturated?
Unsaturated
The following do not require info from the graph above:
13. What is the molarity of a solution that contains 275 g of NaCl in 955 mL
solution? (molar mass of NaCl = 58.44 g/mol)
275 / 58.44 = 4.71 mol NaCl
4.71 / 0.955 = 4.93 M (round at the end)
14. How would you take a saturated solution and make it unsaturated?
Heat it up or add more solvent
15. How many moles of HCl are present in 1.30 L of a 0.63 M HCl solution?
(molar mass of HCl = 36.46 g/mol)
0.63 = n / 1.30
n = 0.82 moles
16. If 220 mL of solvent is added to a 1.2 L 3.0 M solution, determine the
concentration of the final solution.
(3.0) (1.2) = C2 (1.44)
C2 = 2.5 M
17. A NaOH solution contains 0.70 mol of NaOH, and its concentration is 0.345 M.
What is the volume? 0.345 = 0.70 / V (cross multiply)
V = 2.0 L
18. Describe how to dilute 250 ml of a 3.0 M solution to a 1.0 M solution
M1V1 = M2V2
(3.0) (250) = (1.0) V2
V2 = 750 mL
Add 500 mL of solvent to the solution
19. How would you find out if a solution at 50°C was saturated?
Cool it down to see if any precipitate forms or
Add more solute and see if a precipitate forms
20. How many milliliters of a 0.251 M solution contain 2.50 g of NaCl? (molar
mass of NaCl = 58.44 g/mol)
2.50 / 58.44 = 0.0428 moles
0.251 = 0.0428 / V V = 0.170 L  170 mL