1. Aim: How to describe the different types of solutions

2. Review how stuff dissolve
How does an ionic compound such as salt dissolve in water?
How does a molecular compound such as sugar dissolve in water

3. Review temperature and solubility
Increasing temperature of a solution _______________the solubility of a solid.
Increasing temperature of a solution _______________ the solubility of a gas.
Increasing pressure on a solution _______________ the solubility of a gas.

4. Making Iced Tea What can you do to help the sugar crystals dissolve?
The next time you add sugar to unsweetened tea, take notice of the changes to the solution in the following scenarios.
You add the first packet of sugar, and stir until it all dissolves with no sugar settled on the bottom.
You add a second packet of sugar and it takes a little more time for the sugar to dissolve. After stirring for a minute, you realize that there are still some sugar crystals at the bottom of the glass.
After tasting your tea, you decide it is still not sweet enough and add more sugar. However, it all settles at the bottom, and regardless of how much you stir, the crystals stay at the bottom of the cup.
What can you do to help the sugar crystals dissolve?

5. Types of Solutions
In each of the three steps above, you created one of the following types of solutions: saturated, unsaturated, and supersaturated

6. Types of Solutions
Unsaturated Solution- the solution has a small amount of solute dissolved at a certain temperature
More solute can be added to the solution and still dissolve
Saturated Solution – the solution has as much solute as it can hold at a certain temperature
The maximum amount of solute that can completely dissolve in a solution
Supersaturated Solution – the solution has more solute that it can hold at a certain temperature

9. Supersaturated Solution (this picture is showing the addition of 100 g of glucose to 100ml of water at 250C) Note: at 250C, only 91g of glucose will dissolve in 100 ml of water

10. Types of Solutions Return to the steps for making tea.
Label each step as either a saturated, unsaturated, or supersaturated solution

11. Table G Solubility Curve
Table G shows the solubility of many different substance at different temperatures.
1. What is the label of the x-axis
2. What is the label of the y-axis?
3. If the graph displayed the amount of H2O per 200 grams instead of 100 grams, how would the amount of solute to be dissolved change?
4. Describe the general trend in solubility of the salts shown on this graph.
5. NH3 is the exception to this trend. NH3 is gaseous ammonia. Why do you think it has the opposite trend of the other compounds?
6. Which substance is most soluble at 10oC in 100g of water? Least soluble?

12. Solubility curve
Any solution can be made saturated, unsaturated, or supersaturated by changing the temperature.

13. Solubility curve
Saturated
Supersaturated
Unsaturated

14. Solubility curve –Saturated Solutions
Any point on a line represents a saturated solution.
In a saturated solution, the solvent contains the maximum amount of solute.
Example: At 90oC, 40 g of NaCl(s) in 100g H2O(l) represent a saturated solution. Explain.

15. Solubility curve – Unsaturated Solutions
Any point below a line represents an unsaturated solution.
In an unsaturated solution, the solvent contains less than the maximum amount of solute.
Example: At 90oC, 30 g of NaCl(s) in 100g H2O(l) represent an unsaturated solution. 10 g of NaCl(s) have to be added to make the solution saturated. Explain.

16. Solubility curve – Supersaturated Solutions
Any point above a line represents a supersaturated solution.
In a supersaturated solution, the solvent contains more than the maximum amount of solute. A supersaturated solution is very unstable and the amount in excess can precipitate or crystallize.
Example: At 90oC, 50 g of NaCl(s) in 100g H2O(l) represent a supersaturated solution. Eventually, 10 g of NaCl(s) will precipitate (form solid). Explain.

17. How to read a solubility curve
To read a solubility curve, follow these steps
Determine what the question is asking.
Are you looking for temperature
Are you looking fro grams of solute that can be dissolved?
Are you deciding if a solution is saturated, unsaturated, or supersaturated?
Use the information given in the question to read graph.
Use the graph to answer the question.

18. Example 1: 40g – 25g = 15 g more needed
How much more KCl is required to saturate the solution if 25g are dissolved at 40oC?
Read the line value: 40g needed to make a saturated solution at 40oC
Subtract the given value:
40g – 25g = 15 g more needed

19. Example 2:
How much less KCl is dissolved at 20oC than at 60oC in 100g H2O?
Read the line value:
32g at 20oC
45 g at 60oC
Subtract it from the
given value:
45g – 32g = 13 g

20. Solution
Saturated or Unsaturated?
If unsaturated: How much more solute can dissolve in the solution?
a solution that contains 70g of NaNO3 at 30°C (in 100 g H2O)
a solution that contains 50g of NH4Cl at 50°C (in 100 g H2O)
a solution that contains 20g of KClO3 at 50°C (in 100 g H2O)
a solution that contains 70g of KI at 0°C (in 100 g H2O)

21. Homework. Explain how you got your answer.
How many grams of KNO3 are dissolved in 100 g of H2O at 60oC? Explain.
How many grams of NaNO3 would be needed to saturate 200 grams of H2O at 40oC? Explain.
Which solutes vary inversely with temperature? Explain.
If 55 grams of potassium chlorate are mixed with 100 grams of water at 55 oC, how much will not dissolve? Explain.
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?
How many grams of potassium chlorate are needed to make a saturated solution in 50 grams of water at 35 oC? Explain.
If you had a saturated KCl solution at 70oC and cooled it down to 50oC, how much of the solute would precipitate? Explain.
How many grams of NaNO3 can dissolve in 50g of H2O at 10oC? Explain.
If you had 40g of NH3 in 100g of water at 10oC would the solution be saturated, unsaturated or supersatured? Explain.