1. 2-6 Acids/Base Chemistry

2. Just as you can classify compounds as ionic or covalent, you can classify some compounds as being either acids or a bases.

3. Acids Taste sour Release H+ ions in aqueous solution HCl  H+ + Cl-
Produce a solution with a pH less than 7
Can be corrosive
Common Examples:
Ascorbic acid = vitamin C, found in juices & citrus
Stomach acids used to break down food

4. Bases Feel slippery Taste bitter Release OH- ions in aqueous solution
NaOH  Na+ + OH-
Produce a solution with a pH greater than 7
Can be corrosive
Common Examples:
Soap, oven cleaner, baking soda

5. pH Scale
This is a scale (0 – 14) used to indicate how acidic or basic something is
pH < 7 = acidic
pH > 7 = basic
pH = 7 = neutral

6. pH Scale Substances that are closer to 0 are more acidic
Substances that are closer to 14 are more basic
Sometime you will hear bases referred to as alkaline

7. pH Scale The units on the pH are a little strange
Each 1 unit increase actually represents an change in 10x the acidity or basicity
Examples:
pH = 4 is 10x more acidic than pH = 5
pH = 9 is 10x more basic than pH = 8
Regular rain = pH 6, acid rain = pH 4. How much more acidic is the acid rain?

8. pH Scale Lemons are ____ times more acidic than grapes
Tomatoes are ____ times more acidic than grapes
Oven cleaner is _____ times more basic than soap.

9. pH Indicators
Since acids and bases can be dangerous, chemists use special chemicals called indicators to determine whether a solution is acidic or basic
pH indicators change colour.
They are one colour in acids and a completely different colour in bases.

10. pH Indicators Litmus paper: Red in acid, blue in base
Can tell you if a solution is acidic or basic, but not HOW acidic or basic it is.

11. pH Indicators Universal Indicator:
Made up of a number of different indicator solutions that turn different colours for each step in the pH scale
Can give you a general idea of the pH of a solution.

12. pH Indicators pH meters or pH computer probes:
These devices measure electrical properties of solutions to very accurately determine pH

13. pH Indicators

14. Complete the Reading Check Questions on page 225

15. Acids
If you know a compound’s chemical formula, you may be able to identify whether it is an acid. They will have either:
The “H” written at the beginning of the formula. Examples:
HCl (aq) = hydrochloric acid
HNO3(aq) = nitric acid
The “H” written at the end of the formula IF the acid contains the element carbon. Example:
CH3COOH = acetic acid
Acids often behave like acids only when dissolved in water.
Therefore, acids are written with symbol (aq) = aqueous

16. Complete the Reading Check on page 227
Acids
Naming acids
Complete the Reading Check on page 227
Ionic Name
Acid Name
Hydrogen ______ide
Hydro_____ic Acid
Hydrogen ______ate
______ic Acid
Hydrogen ______ite
______ous Acide

17. Bases
If you know a compound’s chemical formula, you may be able to identify it as a base.
Bases often behave like bases only when dissolved in water.
Therefore, bases are often written with the symbol (aq) = aqueous = water.
The chemical formula of a base usually ends with hydroxide (OH).
Bases can be gentle or very caustic.
Examples of common bases:
NaOH(aq)
Mg(OH)2(aq)
Ca(OH)2(aq)
NH4OH(aq)

18. Complete the Reading Check Questions on page 228.

19. Production of Ions
Acids and bases can conduct electricity because they release ions in solution.
Acids release hydrogen ions, H+ .
Bases release hydroxide ions OH–.
The pH of a solution refers to the concentration of ions it has.

20. Production of Ions
Square brackets are used to signify concentration, [H+], [OH–]
High [H+] = low pH, very acidic
High [OH–] = high pH, very basic
A solution cannot have BOTH high [H+] and [OH–]; they cancel each other out and form water. This process is called neutralization.
H+ + OH–  H2O

21. Properties of Acids & Bases

22. Complete Checking Concepts page 233 #1-15

23. Acid-Base Neutralizations

24. Acid + Base  Salt + Water
A neutralization reaction happens when an acid and a base react to form a salt and water.
Acid + Base  Salt + Water
HCl + NaOH  NaCl + H2O
A salt is made up of a positive ion from a base and a negative ion from an acid.

25. Neutralization Reaction
ACID + BASE  SALT + WATER
Neutralization reactions can happen for any acid and base combination
Example:
3H2SO Al(OH)3  Al2(SO4)3 + 6H2O
Acid Base  Salt Water

26. Practice: HCl + KOH  H3PO4 + NaOH  H2CO3 + Mg(OH)2 
CH3COOH LiOH 

27. Complete the Practice Problems on page 236

28. Metal Oxides Metals react with oxygen to form oxides
A compound made up of one or more oxygen with one or more other elements
Metal oxides consist of a metal chemically combined with oxygen
Metal oxides react with water to form bases.
Na2O(s) + H2O(l)  2NaOH(aq)

29. Non-Metal Oxides
Non-metal oxides consist of a non-metal chemically combined with oxygen
Non-metal oxides react with water to form acids.
SO2(g) + H2O(l)  H2SO3(aq)
Non-metal oxides are formed from the burning of fossil fuels.
Acid added to water in the atmosphere = acid precipitation.

30. Practice:
CO H2O 
CaO H2O 
NO H2O 

31. Complete the reading check questions on page 238

32. 2HCl(aq) + Mg(s)  MgCl2(s) + H2(g)
Acids and Metals
The most reactive metals, at the bottom of groups 1 and 2 on the periodic table, react vigorously with water and acids.
All other metals are less reactive than those in groups 1 and 2.
When metals do react with acids, H2 gas is usually released.
2HCl(aq) + Mg(s)  MgCl2(s) + H2(g)

33. Practice:
HCl Zn 
HBr Al 
H2SO4 + Ca 

34. Complete the Practice Problems on Page 238

35. Acids and Carbonates
Much of the carbon dioxide on Earth is trapped in rocks as limestone, dolomite, and calcite that contain carbonate (CO3-2) ions.
Carbonates neutralize acids, protecting locations with natural carbonate supplies from acid precipitation.
H2SO4(aq) + CaCO3(s)  CaSO4(s) + H2O(l) + CO2(g)
sulphuric calcium calcium water carbon
acid carbonate sulphate dioxide

36. Complete the Check Your Understanding questions on page 243 #1-12