1. Solutions Solution Solute Aqueous solution A homogenous mixture
Can be gas, liquid, solid, or combinations.
Solvent
The dissolving medium
Water in salt water
Water in soda
Solute
The dissolved particles
Salt in salt water
Sugar in soda drinks
Aqueous solution
A solution with water as the solvent
Particle size less than 1 nm – cannot be separated by filtration

2. Which formula represents a homogeneous mixture?
H2O (l)
HCl (aq)
H2S (g)
NaH (s)

3. Aqueous Solutions
Water dissolves ionic compounds and polar covalent molecules the best
The rule is: likes dissolve likes
Polar dissolves polar
Nonpolar dissolves nonpolar
Because Oil is nonpolar
Oil and water do not mix
Salt is ionic – dissolves in water

4. The Solution Process
Water molecules are in continuous motion
When NaCl is placed in water, the water molecules collide with the NaCl formula units
Water molecules pull at the + and – charged pieces in the ionic compound
As individual Na+ and Cl- ions break away from the crystal, the + and – charged ions become surrounded by the water molecules and thus the solid crystals disappear or dissolves
See REFERENCE TABLE F for compounds that will dissolve in Aqueous Solutions

5. H H O O O H H O O H O O H H H O O H How ionic solids dissolve in water
These ions have been pulled away from the main crystal structure by water’s polarity. H O H O H O H O H O H O H O H O H O
These ions have been surrounded by water, and are now dissolved! They are hydrated ions.
How ionic solids dissolve in water

6. Which compound is insoluble or will not dissolve in water?
KClO3
BaSO4
Na2S
CaCrO4

7. Which of the following ions when combined with Cl- forms an insoluble substance in water?
Fe2+
Mg2+
Pb2+
Zn2+

8. Based on Reference Table F, which of these solutions has the lowest saturated concentration of dissolved ions?
NaCl(aq)
MgCl2 (aq)
NiCl2(aq)
AgCl(aq)

9. The Nature of Solvent and Solute
Why do some ionic compounds dissolve and others do not?
In some ionic compounds, the attraction between ions is greater than the attraction exerted by water
BaSO4 and CaCO3
Solids will dissolve ONLY if the attractive force of water molecules is stronger than the attractive force of the ionic compound
If not, the solids are insoluble
Water does not dissolve nonpolar molecules (like oil)
Water has no positive or negative site on a Nonpolar molecule to which it would be attracted.

10. Electrolytes and Nonelectrolytes
Compounds that conduct an electric current in aqueous solution OR in the molten state
Conduction of electricity requires ions that are mobile and thus able to carry an electrical current
All ionic compounds are electrolytes because they dissociate into ions (also called salts)
Barium sulfate – will conduct when molten, but is insoluble in water
Nonelectrolytes
Do not conduct electricity
Most are molecular materials because they do not have ions
Polar covalent molecules such as alcohols - methanol (CH3OH) do not fall apart into ions when they dissolve

11. The ions are free to move when they are molten (or in aqueous solution (dissolved)), and thus they are able to conduct the electric current.

12. Factors Affecting the Rate of Solution Formation
In order to dissolve, the solvent molecules must come in contact with the solute
Stirring
Moves the fresh solvent into contact with the solute
2. Size of the particles - Surface area
Smaller pieces increase the amount of surface area of the solute
The more surface area of the solute that is exposed the faster the rate of dissolving

13. Affecting the Rate of Solution Factors Formation
3. Temperature
Higher temperature makes the molecules of the solvent move around faster and contact the solute particles more often, so it speeds up dissolving
Higher temperature also usually increases the amount that will dissolve
Exception – gases
4. Amount of solute already dissolved
When little solute is in solution, dissolving takes place rapidly.
As the amount of solute increases, dissolving rate slows down.

14. Gaseous Solutions Gases tend to dissolve best when
The solution is cold
Pressure is high

15. Solubility How Much? Solubility
The maximum amount of substance that will dissolve at a specific temperature
If the solvent is water the units can be either:
g solute/ 100g water OR g solute/ 100 ml water
Saturated Solution
Contains the maximum amount of solute dissolved at constant temperature and pressure
NaCl = 36.0 g/100 g of water see table G

16. Solubility Unsaturated solution Can still dissolve more solute
Example – 28.0 g NaCl/100 g of water
Can add more solute until the solution is saturated
Once solution is saturated - amount of solute dissolving equals the amount of dissolved solute crystallizing (EQUILIBRIUM)

17. Solubility More solute is dissolving, but some is crystallizing
Saturation equilibrium established
Solute is dissolving

18. Solubility Supersaturated
Solution that is holding more than it theoretically can hold at a given temperature
Adding a “seed crystal” will cause crystallization
Seed crystal = very small crystal of the solute
Disruption of the solution causes the crystallization
Example – rock candy
Video on Supersaturated Solution (1:00)

19. Factors Affecting Solubility
1.Temperature (see Reference Table G)
For solids in liquids
As the temperature goes up – the solubility usually goes up
For gases in a liquid
The effect is the opposite of solids in liquids
As the temperature goes up, gas solubility goes down
Thermal pollution
Water dumped back into a body of water that a factory used for cooling towers temperature of water which lowers solubility of gases (oxygen)

20. If 60 g of KNO3 (s) is dissolved in 100 ml of water at 50 oC, the solution will be:
Saturated
Unsaturated
Supersaturated
Dilute

21. According to your Reference Tables, which substance forms an unsaturated solution when 80 grams of the substance is dissolved in 100 grams of H2) at 10OC?
NaNO3 KI
KNO3
NaCl

22. A saturated solution of NaNO3 is prepared at 60oC using 100 grams of water. As this solution is cooled to 10oC, NaNO3 precipitates (settles) out of the solution. The resulting solution is saturated. Approximately how many grams of NaNO3 settled out of the original solution?
46 g
126 g
61 g
85 g

23. According to Reference table G, which solution contains 50 grams of solute per 100 grams of H2O at 75oC?
A saturated solution of KClO3
A unsaturated solution of KCl
An unsaturated solution of KClO3
A saturated solution of KCl

24. Factors Affecting Solubility
2. Pressure
Change in pressure has LITTLE effect on solubility of solids and liquids
HOWEVER – STRONGLY influences solubility of gases
Gas solubility increases as pressure of the gas above the solution increases
Example – Soda bottle – removing the lid releases the pressure

25. A capped bottle of cola contains CO2 (g) under high pressure
A capped bottle of cola contains CO2 (g) under high pressure. When the cap is removed, how does pressure affect the solubility of the dissolved CO2 (g)?

26. Factors Affecting Solubility
Nature of the solute and solvent
Substances have different degrees of solubility depending on the strength of the attractive forces between the solute particles (ex. polarity, insoluble salts)
ex: lead II chloride vs. zinc chloride
in 100 g of water at the same temperature

27. Concentration
Concentration is a measure of the amount of solute dissolved in a given quantity of solvent
A concentrated solution has a large amount of solute
A dilute solution has a small amount of solute
These are QUALITATIVE descriptions

28. Concentration
You can tell by the color, that the first solution is more concentrated

29. Concentrations Affect on Boiling & Freezing Points
More concentrated solution will increase the boiling point (Boiling Point Elevation)
Salt water boils above 100oC
More concentrated solution will lower the freezing point (Freezing Point Depression).
Salt water freezes below 0oC
The affect on temperature depends on the amount of solute and the NUMBER OF DISSOLVED IONS !!!!!
THE MORE IONS IN A SOLUTE, THE GREATER THE CHANGE IN FREEZING & BOILING

30. - Page 488
CaCl2 will have three particles in solution for each one particle it starts with.
Glucose will only have one particle in solution for each one particle it starts with.
NaCl will have two particles in solution for each one particle it starts with.

31. Compared to the freezing point of 1
Compared to the freezing point of 1.0M KCl(aq) at standard pressure, the freezing point of 1.0M CaCl2 (aq) at standard pressure is
Lower
Higher
The same

32. When Ethylene glycol (an antifreeze) is added to water, the boiling point of the water
Increases, and the freezing point decreases
Decreases, and the freezing point increases
Decreases, and the freezing point decreases
Increases, and the freezing point increases

33. Which ratio of solute to solvent could be used to prepare a solution with the highest boiling point?
1g of NaCl dissolved per 100 g of water
1g of NaCl dissolved per 1000g of water
1g of C12H22O11 dissolved per 100g of water

34. Molarity
A quantitative way to express solution concentration
Molarity - Number of moles of solute dissolved in one liter of solution
Molarity = moles of solute
liters of solution
Abbreviate with M, such as 6.0 M
Note – Volume involved is the total volume of the resulting solution not the volume of the solvent alone
See REFERENCE TABLE T

35. Household laundry bleach is a dilute solution of sodium hypochlorite (NaClO). How many moles of solute are present in 1.5L of 0.7M NaClO?

36. Intravenous (IV) saline solutions are often administered to patients in the hospital. One saline solution contains 0.90g NaCl in exactly 100mL of solution. What is the molarity of the solution?

37. What is the total number of grams of NaI (s) needed to make 1
What is the total number of grams of NaI (s) needed to make 1.0 Liter of 0.010M solution?
1.5 g g
15 g
0.15 g

38. Parts per Million
Parts per Million (ppm) is often used when only small amounts of solute are dissolved in a solvent.
Calculated by dividing the mass of the solute by the mass of the solution (total mass of solvent + solute) and multiplying by 1,000,000
ppm = mass of solute X 1,000,000
mass of solution
See Reference Table T

39. What is the concentration of a solution, in parts per million, if 0
What is the concentration of a solution, in parts per million, if 0.02grams of Na3PO4 is dissolved in 1000 grams of water?
2 ppm
0.2 ppm
0.02 ppm
20 ppm

40. How many grams of C6H12O6 are needed to dissolve in water to make 100 grams of a 250 ppm solution
4.00 x 105g
2.50 x 10-4g
4.00 x 10-1g
2.50 x 10-2g

41. Percent Solutions
Percent solutions are another way to describe the concentration of a solution
Percent of solute in the solvent
Percent solutions can be expressed by
Volume
Mass
Percent means parts per 100

42. What is the percent by volume of ethanol (C2H6O) in the final solution when 85 mL of ethanol is diluted with a volume of 250 mL of water?

43. What is the percent by mass concentration of a solution where 2
What is the percent by mass concentration of a solution where 2.0g of salt are dissolved in 10.0g of water?

44. Websites
Video on Solution and Solvent (1:37 minutes):
Solution Animation(30 seconds):
Dissolving Salt (47 seconds):
Water “to stick or not to stick” (7:42 minutes):
Water simulation Video(less than 1 minute):
World of Chemistry – Water Video link:

45. Do Now Problem What is meant by the term polarity?
Polarity refers to the dipole resulting from electro-negativity differences between covalently bonded atoms
What part of the water molecule has a partial negative charge?
Oxygen atom
What part of the water molecule has a partial positive charge?
Each Hydrogen atom