# Solubility Curve Qs - 4pgs - sch3u-lp-2013

SCH3U

Solutions & Solubility

## Solubility Curve Practice Problems

Look at the solubility curves graph attached. You'll notice that for most substances, solubility increases as temperature increases. As discussed earlier in solutions involving liquids and solids typically more solute can be dissolved at higher temperatures. Can you find any exceptions on the graph? __________________________

Here's an example of how to read the graph. Find the curve for KClO will dissolve in 100g of water. If the temperature is increased to 80°C, approximately _________ of the substance will dissolve in 100g (or 100mL) of water.

3

. At 30°C approximately 10g of KClO

3

1) What mass of solute will dissolve in 100mL of water at the following temperatures? a.

b.

KNO

3 at 70°C = ____________

NaCl at 100°C= ____________ c.

d.

NH

4

Cl at 90°C= ____________

Which of the above three substances is most soluble in water at 15°C. = ____________

2)

Identifying Types of Solutions:

On a solubility curve, the lines indicate the concentration of a __________________ solution - the maximum amount of solute that will dissolve at that specific temperature.

Values on the graph ____________ a curve represent unsaturated solutions - more solute could be dissolved at that temperature.

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 solute can dissolve in the solution?

a solution that contains 70g of

NaNO

3

at 30°C (in 100 mL H

2

O) a solution that contains 50g of

NH

4

Cl at 50°C (in 100 mL H

2

O) a solution that contains 20g of

KClO

3

at 50°C (in 100 mL H

2

O) a solution that contains 70g of KI at 0°C (in 100 mL H

2

O)

1

3. a) What is the solubility of KCl at 5

C? _______

b) What is the solubility of KCl at 25

C? _______

c) What is the solubility of Ce

2

(SO

4

)

3 at 10

C? _______

d) What is the solubility of Ce

2

(SO

4

)

3

at 50

C? _______

4. a) At 90

C, you dissolved 10 g of KCl in 100. g of water. Is this solution saturated or unsaturated?

b) How do you know?

5. A mass of 100 g of NaNO

3

is dissolved in 100 g of water at 80ºC. a) Is the solution saturated or unsaturated?______________________________ b) As the solution is cooled, at what temperature should solid first appear in the solution? Explain.

6. Use the graph to answer the following two questions: a) Which compound is most soluble at 20 ºC? ________ b) Which is the least soluble at 40 ºC? ________ c) Which is least soluble at 10

C? __________

8. Graph the following data on a piece of graph paper.

Sodium Chloride Solubility Copper Sulfate Solubility

(

Temperature

0

C)

10

20

30

Solubility

(g of solute/100 mL of H

35.7

35.8

35.9

36

2

O)

40 36.4

60

80

37.1

38

90

100

38.5

39.2

2. Use the graph you just created to answer the following questions:

(

Temperature

0

C)

10

20

30

40

60

80

100

Solubility

(g of solute/100 mL of H

2

O)

23

27.5

32

38

44.5

62

84

114

Solution A: 35.7 grams of sodium chloride dissolved in 100 mL of water at 25

C

Solution B: 61.0 grams of or copper sulfate dissolved in 100 mL of water at 45

C a) Which solution was saturated? Which was unsaturated? Explain. b) How much more solute could you add to the unsaturated solution?

2

Be neat and organized (use a ruler)

X and Y axis must have proper scale

Have properly labeled axes

Use a different color for the two different solubility curves.

3

4