1. Solutions
To play the movies and simulations included, view the presentation in Slide Show Mode.

2. Solutions
Solutions are homogeneous mixtures of two or more pure substances.
In a solution, the solute is dispersed uniformly throughout the solvent

3. Parts of a Solution
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
Solute
Solvent
Example
solid
liquid
gas

4. How Does a Solution Form?
As a solution forms, the solvent pulls solute particles apart and surrounds, or solvates, them.

6. Can you make a sol’n from anything?
The intermolecular forces between solute and solvent particles must be strong enough to compete with those between solute particles and those between solvent particles

7. “LIKE DISSOLVES LIKE”
Substances with similar types of intermolecular forces dissolve in each other
When a solute dissolves in a solvent, solute-solute interactions and solvent-solvent interactions are partly replaced with solute-solvent interactions.
The new forces created between solute & solvent must be comparable in strength to the forces destroyed within the solute& the solvent

9. Student, Beware!
Just because a substance disappears when it comes in contact with a solvent, it doesn’t mean the substance dissolved

10. Solutions can be classified as saturated or unsaturated
More Definitions
Solutions can be classified as saturated or unsaturated
A saturated solution contains the maximum quantity of solute that dissolves at THAT temperature.
An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature

11. Example: Saturated and Unsaturated Fats
Saturated fats are called saturated because all of the bonds between the carbon atoms in a fat are single bonds. Thus, all the bonds on the carbon are occupied or “saturated” with hydrogen. These are stable and hard to decompose. The body can only use these for energy, and so the excess is stored. Thus, these should be avoided in diets. These are usually obtained from sheep and cattle fats. Butter and coconut oil are mostly saturated fats.
Unsaturated fats have at least one double bond between carbon atoms; monounsaturated means there is one double bond, polysaturated means there are more than one double bond. Thus, there are some bonds that can be broken, chemically changed, and used for a variety of purposes. These are REQUIRED to carry out many functions in the body. Fish oils (fats) are usually unsaturated. Game animals (chicken, deer) are usually less saturated, but not as much as fish. Olive and canola oil are monounsaturated.

12. MORE Definitions
SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved
Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways:
Warm the solvent so that it will dissolve more, then cool the solution
Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution

13. Supersaturated
Solvent holds more solute than is normally possible at that temperature.
These solutions are unstable; crystallization can usually be stimulated by adding a “seed crystal” or scratching the side of the flask.

14. Supersaturated example Sodium Acetate
When heated, sodium acetate melts, but when it cools back down to the temperature when it was solid, it doesn't go back to being a solid. It stays a liquid.
A single crystal of sodium acetate or a disturbance from the "activator button" can cause the liquid sodium acetate to turn to a solid. At that point heat is released. The reason is that molecules in a liquid are moving around, but molecules in a solid are not moving around. Motion is energy, more specifically kinetic energy. When these molecules come to an abrupt halt as they go from liquid to solid, that kinetic energy has to go somewhere. That's the heat that is given off.

16. IONIC COMPOUNDS Compounds in Aqueous Solution
Many reactions involve ionic compounds.
When a substance is dissolved in water, it is called an aqueous sol’n (aq)
KMnO4 in water
K+(aq) + MnO4-(aq)
To play the movies and simulations included, view the presentation in Slide Show Mode.

17. Aqueous Solutions
How do we know ions are present in aqueous solutions?
The solutions conduct electricity.
They are called ELECTROLYTES
HCl, MgCl2, and NaCl are strong electrolytes.
They dissociate completely (or nearly so) into ions.

18. Aqueous Solutions
Some compounds dissolve in water but do not conduct electricity.
They are called nonelectrolytes.
Examples include:
sugar
ethanol
ethylene glycol

19. Three types of electrolytes
strong
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non-electrolyte
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
weak
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

20. Electrolytes in the Body
Make your own Electrolyte
50-70 g sugar
One liter of warm water
Pinch of salt
200ml of sugar free fruit squash
Mix, cool, and drink
Carry messages to and from the brain as electrical signals
Maintain cellular function with the correct concentrations electrolytes

21. Concentration of Solute
The amount of solute in a solution is given by its concentration.
Molarity ( M ) =
moles solute
liters of solution

23. Making a Molar Solution
So, you want to make a molar sol’n?
INFORMATION YOU NEED TO MAKE SOL’N
- Volume needed (in mL or L)
- Concentration needed (in mol)
- Periodic Table & Calculator
Ex. Make 1L of 1M NaCl

24. x M = 1.0 M = x mol 1.0 L x = 1.0 mol y mol z L Ex. Make 1L of 1M NaCl
So, I just need 1.0 mol worth of NaCl…
How can I weigh out 1 mol of NaCl???

25. So, how much does 1mol weigh??? So, what do I do with that number????
How to Make 1L of 1M NaCl
Volume needed = 1.0L
[Concentration] = 1mol
So, how much does 1mol weigh???
1 mol of NaCl = = 58.44g
So, what do I do with that number????

26. 1 mol of NaCl = = 58.44g
So, I weigh out 58.44g of NaCl & put into a g.cyl and add water until it reaches 1L (“QS”)
I now have 1L of a 1M NaCl sol’n
QS = “Quantity Sufficient”
Means add as much water as you need to get the final volume you want 

27. 1. 0 L of water was used to make 1. 0 L of solution
1.0 L of water was used to make 1.0 L of solution. Notice the water left over.

28. 1 M = y mol 0.5L What if I want 0.5L of 1M NaCl? x M = y = 0.5 mol
z L
1 M = y mol 0.5L
y = 0.5 mol
0.5 mol (58.44 g/mol) = 29.22g NaCl

29. I now have 0.5L of a 1M NaCl sol’n
y mol
x M =
z L
So, I weigh out 29.22g of NaCl & put into a g.cyl and add water until it reaches 0.5L (“QS”)
I now have 0.5L of a 1M NaCl sol’n

30. Volume needed = 400mL Concentration = 1.2M 1.2 M = y mol 0.4 L x M =
Make 400mL of 1.2M NaCl
Volume needed = 400mL
Concentration = 1.2M
1.2 M = y mol
0.4 L
x M =
y mol
z L

31. 0.48 mol NaCl (58.44g/mol) = 28.1 g NaCl, QS to 0.4L
- Solve for y moles
y mol = (1.2 M)(0.4L)
= 0.48 mol NaCl
Change mol to g
0.48 mol NaCl (58.44g/mol)
= 28.1 g NaCl, QS to 0.4L

32. Dissolve 5.00 g of NiCl2•6 H2O in enough water to make 250 mL of solution. Calculate the Molarity.
Step 1: Calculate moles of NiCl2•6H2O
Step 2: Calculate Molarity
[NiCl2•6 H2O ] = M
[ ] = “concentration”

33. More Practice ... x M = ymol=xM•zL y mol z L Step 1: Change mL to L
What mass of oxalic acid, H2C2O4, is required to make 250 mL of a 0.05 M solution?
x M =
y mol
z L
ymol=xM•zL
Step 1: Change mL to L
250 mL * 1L/1000mL = L
Step 2: Calculate
Moles = ( mol/L) (0.250 L) = mol
Step 3: Convert moles to grams
( mol)(90.00 g/mol) = g

35. Colligative Properties
After you add a solute to a solvent, the properties of the solvent are changed:
Vapor pressure decreases
Melting point decreases
Boiling point increases
These changes are called COLLIGATIVE PROPERTIES
They depend only on the NUMBER of solute particles relative to solvent particles, not on the KIND of solute particles.

37. CHANGE IN FREEZING POINT
Ethylene glycol/water
solution
Pure water
The freezing point of a solution is LOWER than that of the pure solvent

38. CHANGE IN FREEZING POINT
Common Applications of Freezing Point Depression
Ethylene glycol – deadly to small animals
Propylene glycol

39. Change in Boiling Point
Common Applications of Boiling Point Elevation

40. Temperature
Generally, the solubility of solid solutes in liquid solvents increases with increasing temperature

41. The opposite is true of gases:
Temperature
The opposite is true of gases:
Carbonated soft drinks are more “bubbly” if stored in the refrigerator
Warm lakes have less O2 dissolved in them than cool lakes

42. SUSPENSIONS Mixtures with large particles NOT a solution
(The solvent does NOT dissolve the solute)
Usually “murky” or “opaque”
Separate on standing

43. COLLOIDS
- Mixtures that contain “clumps” of molecules (still too small to be seen by the naked eye)
Often look “cloudy”
Do NOT separate upon standing

44. Tyndall Effect Colloidal suspensions can scatter rays of light
This phenomenon is known as the Tyndall effect

45. Light scattering and the Tyndall effect

46. Dilution
Dilution is the process of decreasing the concentration of a stock solution by adding more solvent to the solution.
A stock solution is a concentrated solution that will be diluted to a lower concentration for actual use.
The equation for dilution is M1V1=M2V2
M1= molarity of the stock solution
M2= molarity of the diluted solution
V1= volume of stock solution
V2= volume of diluted solution

47. Dilution Example What we know:
A stock solution of 1.00M of NaCl is available. How many milliliters are needed to make a mL of 0.750M?
What we know:
the molarity of the stock solution which is 1.00M, and the two components of the diluted solution which are M2= 0.750M and V2= 100 mL.
M1V1=M2V2