1. Solutions Solute Solvents

2. What is a solution?
A solution is a homogeneous mixture of 2 or more substances in a single phase.
solute
One constituent is usually regarded as the SOLVENT and the others as SOLUTES.
solvent

3. Parts of a Solution Solution Solvent Solute
SOLUTE – the part of a solution that is being dissolved (usually the lesser amount)
SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)
Solute + Solvent = Solution
Solvent
Solute
Solution

4. Nature of Solutes in Solutions
Spread evenly throughout the solution
Cannot be separated by filtration
Can be separated by evaporation
Not visible, solution appears transparent
May give a color to the solution

5. Soluble/Insoluble vs. Miscible/Immiscible
SOLUBLE – a substance that can be dissolved.
Insoluble – a substance that cannot be dissolved
MISCIBLE – a liquid substance that is soluble in another liquid.
IMMIsCIble – a liquid substance that is insoluble in another liquid.
Immiscible
Miscible

6. Examples Salt added to water: - The solute is the The solvent is the
This makes a
The salt is as it has
soluble
salt
water
solution
dissolved
Flour added to water. Stirring it makes it go cloudy, but after a while all the flour grains sink to the bottom:
The flours has not
This is because flour is
dissolved
insoluble

7. Where
So when a solute dissolves, such as salt in water, where does it go? Does it disappear?
The solute does not disappear - its still there! But you cannot see it because the particles are now mixed up (dissolved)
Look at the particle box below - can you draw a particle box for a solid which has dissolved (e.g. salt in water)
Salt, added to the water
Water

8. Water
Salt, added to the water
The number of salt particles and the number of water particles remains the same - we haven’t lost any salt particles, nor have they got smaller. They’re just spread out amongst the water particles, which is why we can no longer see them (it looks as if the salt has disappeared)!

9. Flour, added to the water
Look at the particle box below - can you draw a particle box for an insoluble solid in a liquid (e.g. flour in water)
Flour, added to the water
Water

10. Flour, added to the water
Look at the particle box below – solid in a liquid (e.g. flour in water)
Flour does not dissolve -- it is insoluble
Water
Flour, added to the water
Remember - the number of particles and their size stays the same! However this time we can still see the flour, as the flour particles remain grouped together (not mixing, not dissolving)

11. Dissolution vs reaction
dry
Ni(s) + HCl(aq)
NiCl2(aq) + H2(g)
NiCl2(s)
Dissolution is a physical change—you can get back the original solute by evaporating the solvent.
If you can’t, the substance didn’t dissolve, it reacted.
IPC-Solutions-Borders

12. Types of Solutions Gaseous solutions Liquid solutions (most common)
Solid solutions--alloys

13. Types of Solutions water salad soil Examples Gas in a Gas  Air
Gas in a Liquid  Soda
Liquid in a Liquid  Gasoline
Solid in a Liquid  Sea Water
Solids in Solids  Brass
Non-Examples
water
salad
soil

14. Solutions How does a solid dissolve into a liquid?
IPC-Solutions-Borders

15. How Does a Solution Form?
Solvent molecules are attracted to surface ions.
Each ion is surrounded by solvent molecules.
Ionic solid dissolving in water
IPC-Solutions-Borders

16. The amount of solute that dissolves can vary
Concentration: The amount of solute dissolved in a solvent at a given temperature.
Examples:
Hot chocolate…the more powdered mix you add the higher the concentration of chocolate
Lemonade…the more frozen lemon concentrate or powdered mix you add the more tart the drink becomes

17. Degrees of Concentration
Degrees of Concentration
Dilute or Unsaturated: a solution has a low concentration of solute
Saturated: a solution that contains the maximum amount of solute that can be dissolved into the solvent at a given temperature.
Supersaturated: a solution can contain more solute than normal by raising the temperature of the solvent.

18. Degree of saturation Unsaturated Solution
Less than the maximum amount of solute for that temperature is dissolved in the solvent.
No solid remains in flask.

19. Degree of saturation Saturated solution
Solvent holds as much solute as is possible at that temperature.
Undissolved solid remains in flask.
Dissolved solute is in dynamic equilibrium with solid solute particles.

20. Saturated Solution

21. Degree of saturation Supersaturated Solution
Solvent holds more solute than is normally possible at that temperature.
These solutions are unstable; crystallization can often be caused by adding a “seed crystal” or scratching the side of the flask.

22. Which solution has the greatest, the least and no concentration of solute?

23. Figure 12.11: Solubility of some ionic salts.

24. What are ways that you make a solute dissolve faster in water?
Solubility of a Solute
What are ways that you make a solute dissolve faster in water?
Increase the temperature.
Increase the pressure
Crush or use smaller size solute particles.
Stir the solutions.

25. Solubility and Temperature
Solute
Increased Temperature
Decreased Temperature
Solid
Increase in solubility
Decrease in solubility
Gas

26. Gases in Solution
Sudden release of pressure from a carbonated beverage.
Increasing pressure above solution forces more gas to dissolve.

27. Solubility and Pressure
Solute
Increased Pressure
Decreased Pressure
Solid
No effect on solubility
Gas
Increase in solubility
Decrease in solubility

28. Which of these sugar cubes will dissolve the fastest and how do you know?

29. Solubility Curves
Solubility indicates the amount of solute that will dissolve in a given amount of solvent at a specific temperature.
For this curve,
X-Axis
Temperature
Y-Axis
How Much Solute Dissolves in 100g of Water
Various Lines
Each line represents a different solute.

30. Solubility Curves
Supersaturated
CO2
Saturated
Unsaturated

31. Using an available solubility curve, classify as
unsaturated, saturated,
or supersaturated.
per 100 g H2O
1. 80 g 30oC
unsaturated
2. 45 g 60oC
saturated
3. 30 g 30oC
supersaturated
4. 70 g 60oC
unsaturated

32. Describe each situation below.
5. Per 100 g H2O,
100 g 50oC.
unsaturated;
all solute dissolves;
clear solution.
6. Cool solution (A) very
slowly to 10oC.
supersaturated;
extra solute remains
in solution; still clear
7. Quench solution (A) in
an ice bath to 10oC.
saturated; extra solute (20 g)
can’t remain in solution and becomes visible

33. How to use a solubility graph?
A. IDENTIFYING A SUBSTANCE ( given the solubility in g/100 cm3 of water and the temperature)
Look for the intersection of the solubility and temperature.

34. Using Solubility Curves
8. How much KNO3 would dissolve in 100g of water at 50oC?
9. How much NH4Cl would dissolve in 200g of water at 70oC?
10. At what temperature would 22g of KCl be able to dissolve in 50g of water?
11. Which is more soluble (has a higher solubility) at 40oC?
NH3
KClO3
84g
120g
68oC

35. Learning Check : 12. What substance has a solubility of 90 g/100 cm3 in water at a temperature of 25ºC ?

37. Learning Check :
13. What substance has a solubility of 200 g/100 cm3 of water at a temperature of 90ºC ?

39. Look for the temperature or solubility
Locate the solubility curve needed and see for a given temperature, which solubility it lines up with and visa versa.

40. Learning Check: 14. What is the solubility of potassium nitrate at 80ºC ?

41. 14. What is the solubility of potassium nitrate at 80ºC ?

42. Learning Check : 15. At what temperature will sodium nitrate have a solubility of 95 g/100 cm3 ?

43. Learning Check: 15. At what temperature will sodium nitrate have a solubility of 95 g/100 cm3 ?

44. Learning Check: 16. At what temperature will potassium iodide have a solubility of 230 g/100 cm3 ?

45. Learning Check: 17. At what temperature will potassium iodide have a solubility of 130 g/100 cm3 ?

46. Using Solubility Curves: 18
Using Solubility Curves: 18. What is the solubility of sodium chloride at 25ºC in 100 cm3 of water ?
From the solubility graph we see that sodium chlorides solubility is 36 g.