1. Solutions, Acids, and Bases
Chapter 7 & 8

2. Parts of a solution Solute
The substance that is dissolved into the solution.
examples:
Sugar in kool-aid
Salt in salt water
CO2 in soda
Solvent
The substance that does the dissolving in a solution.
examples:
Most common is water.

3. Dissolving Three ways to dissolve a solute in a solvent: Dissociation
Dispersion
Ionization

4. 1. Dissociation
The process in which an ionic compound separates into ions in a solution. (physical change)
Example: salt in water

5. 2. Dispersion
Breaking the solute into small pieces and spreading throughout the solvent.
Ex. Sugar in water
Physical change

6. 3. Ionization
The process in which neutral molecules lose or gain electrons.
Chemical change

7. Conductivity
Many solutions can conduct an electric current if electrolytes are present. (ions)
Electrolytes = substances that will conduct an electric current when dissolved. Ex. NaCl, KCl, MgBr2

8. Freezing Point Depression
Lowering the freezing point of water by the addition of a solute
ex. salt.
Used on icy roads in winter
Ice-cream

9. Boiling point elevation
The addition of a solute to a liquid solvent will usually raise the boiling point of the solvent.
Adding salt to boil water when cooking

10. Heat of Solution
A measure of the amount of energy either absorbed or released when a solute dissolves in a solvent.
Can be endothermic or exothermic.

11. Rate of Solution Speed at which solute dissolves in a solvent.
1st Stirring the solution. Helps to move the solute particles away from the solid solute.

12. Other factors: 2nd : Powdering the solute. Increases the surface area
3rd : Heating the solution.
Speeds up the molecules

13. Concentration Concentrated
A large amount of solute dissolved in a solvent
Dilute
A little bit of solute dissolved in a solvent

14. Saturation
A solution that contains all the solute it can possibly hold at a given temperature is said to be saturated.
Unsaturated = contains less solute than it can possibly hold
Supersaturated = a solution that holds more solute than it should at a given temperature.

15. Supersaturation example:
Sodium acetate in water.
Used in commercial hand warmers.

17. Insoluble
A substance that will NOT dissolve in water.

18. “Like dissolves like”
Nonpolar solvents will dissolve nonpolar solutes.
examples: benzene & acetone
Polar solvents will dissolve polar solutes

19. 2 factors that affect solubility:
1.Temperature
Increase in temp generally increases solubility of a solid in a liquid
Increase in temp decreases solubility of a gas in a liquid.
2. Pressure
Usually has little, if any, effect on solid and liquid solutes.
Increase in pressure increases the solubility of a gas in a liquid.

20. Specific concentration
Can be defined as percent by volume or percent by mass
Example: 3% hydrogen peroxide or 25% fruit juice.

21. MOLARITY

22. Acids
Very important chemicals in everyday life processes.

23. Properties of acids: Sour taste (never taste a chemical)
All contain hydrogen
Also called “proton donors”
React with active metals to produce hydrogen gas.
Zn HCl ZnCl H2

24. Indicators
Chemicals used to identify acids and bases by changing color.
ACIDS:
Litmus paper (blue to red)
Phenolphthalein (colorless)
Methyl Orange (orange to red)
Bromothymol Blue (changes to yellow)

25. Common acids Sulfuric (H2SO4) used in car batteries
Nitric (HNO3) used in fertilizers
Hydrochloric (HCl) stomach acid
Carbonic (H2CO3) carbonated drinks
Acetic (HC2H3O2) vinegar

26. Bases
Also very important in everyday processes.

27. Properties of Bases: Taste bitter; feel slippery
Contain hydroxide (OH) ions.
Known as “proton acceptors”
Phenolphthalein turns bright pink
Red litmus paper turns blue
Bromothymol blue turns blue
Methyl orange turns yellow

28. Common bases: Sodium hydroxide NaOH making soap; drain cleaners
Potassium hydroxide KOH battery electrolyte
Calcium hydroxide Ca(OH)2 making plaster and drywall
Magnesium hydroxide Mg(OH)2antacids

29. Solutions of acids and bases
pH scale
A numerical scale developed to measure the relative strengths of acids and bases
Ranges from 0 to 14
0 is the strongest acid
14 is the strongest base.

30. What happens when an acid and a base combine?
Always forms water and a salt.
Salt = ionic compound formed when a positive ion of a base combines with a negative ion of an acid.
Neutralization.
These are double replacement reactions.

32. What determines if an acid is classified as “strong” or weak?
Strength is determined by how well the acid or base dissociates into solution.
Strong acids and strong bases are good electrolytes.

33. Buffers A mixture of a weak acid or weak base with its salt.
Resists large changes in pH.
Examples:
Bicarbonate ions in your blood stream.