Section 1C.1 & C.2 Reading Solubility Curves

Using the Solubility Graph provided, answer the following questions on your own paper.

What is Solubility?

The maximum amount of a substance that will dissolve in a certain amount of solvent at a given temperature is called that substances solubilitysolubility in that solvent

SoluteSolute = is dissolved SolventSolvent = does the dissolving Example: __ grams of salt (NaCl) in 100 g

of water at __ ˚C.

Temperature and Solubility

The temperaturetemperature of the solution affects how much of the solute is dissolved by the solvent.

Increasing the temperature does not does not alwaysalways increase the solubility.

Solubility curvesSolubility curves are used to show how the solubility of a substance changes with temperature.

Solubility Curve Regions

To read the graph, find the line for the substance. The amount that dissolves at a given temperature is on the y-axis.

How much KNO3 dissolves in 100g H2O at 50oC?

1. Find the line (red)

2. Find the temperature and follow up to the line. (green)

3. Read across to the y-axis and this is the answer. (blue)

4. Since it is above the ½-way between 80 and 90, it is 87.

To do calculations: A point on the line is a saturated solution. Above the line is supersaturated. Below the line is unsaturated. To calculate how much extra has been

dissolved, subtract the line value at that temperature.

To calculate how much more can be dissolved, subtract the value given from the line value at that temperature.

Example 1:

How much more KCl is dissolved at 20oC than would normally if 45g are in 100g H2O?

Read the line value: 32g at 20oC Subtract it from the given value:

45g – 32g = 13 g This is the answer

Example 2:

How much more KCl is required to saturate the solution if 25g are dissolved at 40oC?

Read the line value: 40g Subtract the given value:

40g – 25g = 15 g This is the answer

Your turn! Use your graph

1. How much NaCl will dissolve in 100g H2O at 35oC?

2. How much NH4Cl will dissolve at 50oC?

3. What is the solubility of SO2 at 25oC?

4. What is the solubility of potassium chlorate in 100 grams of water at 35oC?

5. What is the solubility of potassium iodide in 100 grams of water at 10oC?

6. What minimum temperature needed to dissolve 80 grams of sodium nitrate in 100 grams of water?

7. What minimum temperature needed to dissolve 42 grams of potassium chloride in 100 grams of water?

8. What minimum temperature needed to dissolve 20 grams of KClO3 in 100 grams of water?

9. If 95 grams of potassium nitrate are mixed with 100 grams of water at 45 oC, how much will not dissolve?

10. If 85 grams of potassium iodide are mixed with 100 grams of water at 0 oC, how much more must be added to saturate the solution?

11. If 55 grams of potassium chlorate are mixed with 100 grams of water at 55 oC, how much will not dissolve?

12. If 125 grams of potassium iodide are mixed with 100 grams of water at 10 oC, how much more must be added to saturate the solution?

13. What is the solubility of potassium chlorate in 50 grams of water at 35 oC?

14. What is the solubility of potassium chlorate in 100 grams of water at 35 oC?

15. What is the solubility of potassium iodide in 100 grams of water at 10 oC?

16. What is the minimum temperature needed to dissolve 80 grams of sodium nitrate in 100 grams of water?

17. What is the minimum temperature needed to dissolve 42 grams of potassium chloride in 100 grams of water?

18. What is the minimum temperature needed to dissolve 20 grams of KClO3 in 100 grams of water?

19. If 95 grams of potassium nitrate are mixed with 100 grams of water at 45 oC, how much will not dissolve?

20. If 55 grams of potassium chlorate are mixed with 100 grams of water at 55 oC, how much will not dissolve?

21. If 125 grams of potassium iodide are mixed with 100 grams of water at 10 oC, how much more must be added to saturate the solution?

22. If 85 grams of potassium iodide are mixed with 100 grams of water at 0 oC, how much more must be added to saturate the solution?

23. What is the solubility of potassium chlorate in 50 grams of water at 35 oC?

Turn in your work