1. Intro to Acids & Bases

2. Properties of Acids & Bases
Taste sour
Reacts with metals
Turns litmus red
Conducts electricity
Base
Taste bitter
Slippery
Turns litmus blue
Conducts electricity

3. Ions in Solution Acidic solutions – contain more H+ than OH-
Basic solutions – contain more OH- than H+
Neutral solutions – contain equal amounts of H+ and OH-

4. Autoionization of Water
H2O + H2O  H3O+ + OH-
H3O+ = hydronium ion
Water is the usual solvent for acids and bases
It produces equal numbers of H3O+ and OH-

5. Arrhenius Model of Acids & Bases
Acid: a substance that contains H and ionized to produce H+ when dissolved in water.
Base: a substance that contains OH and ionizes to produce OH- when dissolved in water

6. Arrhenius Model of Acids & Bases
HCl  H+ + Cl-
HCl contains H and ionizes to form H+
This could be an Arrhenius acid
NaOH  Na+ + OH-
NaOH contains OH and ionized to form OH-
This could be considered an Arrhenius base

7. Arrhenius Model of Acids & Bases
Although the Arrhenius model is useful in describing many acids and bases, it does not describe them all
For example NH3 contains no OH- ions, but it is a base
A model to describe all bases is needed

8. Lewis acids/bases: acid: accepts an electron pair base: donates an electron pair The advantage of this theory is that many more reactions can be considered acid-base reactions because they do not have to occur in solution.

9. Bronsted-Lowry Model Acid: proton donor Base: proton acceptor
HX + H20  H3O+ + X-
HX donates an H+ to the water molecule
The water takes the H and is there for considered the base

10. Bronsted-Lowry Model
Conjugate acid – the species produced when a base accepts the H+ ion from the acid
Conjugate base – the species produced when the acid gives up its H+

11. Conjugate Acids & Conjugate Bases
Identify the acid, base, conjugate acid, and conjugate base of the following reaction…
HX + H20  H3O+ + X-
A B CA CB
Every Bronsted-Lowry interaction involves conjugate acid base pairs

12. Conjugate Acids & Conjugate Bases
Identify the acid, base, conjugate acid, and conjugate base of the following reaction…
NH3 + H20  NH4+ + OH-
B A CA CB

13. Conjugate Acids & Conjugate Bases
What did you notice that was different about the previous two reactions?
Water was an acid in one and a base in the other
Amphoteric – substance that can act as either an acid or a base

14. Conjugate Acids & Conjugate Bases
Identify the acid, base, conjugate acid, and conjugate base of the following reactions…
NH4+ + OH-  NH3 + H20
A B CB CA
HBr + H2O  H3O+ + Br -
A B CA CB

15. The pH Scale
[H+] is often expressed in very small numbers. Chemists needed an easier way to express [H+] ions
pH is a mathematical scale in which the concentration of hydronium ions in a solution is expressed as a number from 0 to 14.
pH = -log[H+]

16. Interpreting the pH Scale
pH of 7 is neutral. A pH less than 7 is acidic, and a pH greater than 7 is basic.
pH + pOH = 14

17. Acid Strength
The strength of an acid or a base tells you the degree of ionization
Strong acids & bases break down into many ions
Weak acids & bases break down into just a few ions

18. Acid-Base Character
For a molecule with a H-X bond to be an acid, the hydrogen must have a positive oxidation number so it can ionize to form a positive +1 ion.
For instance, in sodium hydride (NaH) the hydrogen has a -1 charge so it is not an acid but it is actually a base.

19. Molecules like CH4 with nonpolar bonds also cannot be acids because the H does not ionize.
Molecules with strong bonds (large electronegativity differences), are less likely to be strong acids because they do not ionize very well.

20. For a molecule with an X-O-H bond (also called an oxyacid) to be an acid, the hydrogen must again ionize to form H+.
To be a base, the O-H must break off to form the hydroxide ion (OH-). Both of these happen when dealing with oxyacids.

21. Strong Acids: These acids completely ionize in solution so they are always represented in chemical equations in their ionized form. There are only seven (7) strong acids:
HCl, HBr, HI, H2SO4, HNO3, HClO3, HClO4

22. Neutralization Reactions
Neutralization reactions – acid + base  a salt + water
Neutralization reactions are just a special type of double replacement reactions

23. Weak Acids: These are the most common type of acids
Weak Acids: These are the most common type of acids. They follow the equation:
HA(aq) <---> H+(aq) + A-(aq)

24. Strong Bases:
Like strong acids, these bases completely ionize in solution and are always represented in their ionized form in chemical equations. There are only eight (8) strong bases:
LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2

25. Weak Bases: They follow the equation:
Weak Base + H2O <---> conjugate acid + OH-
example: NH3 + H2O <---> NH4+ + OH+

26. Neutralization Reactions
Write the equations for the following neutralization reactions
Acetic acid and ammonium hydroxide
HC2H3O2 + NH4OH  H2O + NH4C2H3O2
Nitric acid and cesium hydroxide
HNO3 + CsOH  H2O + CsNO3

27. Neutralization of a Strong Acid by a Strong Base
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28. Double Replacement #4 (Acid Base neutralization)
Acid + base  salt + water
Hydrogen sulfide gas is bubbled through excess potassium hydroxide solution
H2S + 2KOH  2HOH + K2S
H2S + 2K+ + 2OH-  2H2O + 2K+ + S-2
H2S + 2OH-  2H2O + S-2

29. Double Replacement #4 (Acid Base neutralization)
READ the question especially for polyprotic acids!!!
If you have a polyprotic acid & the base is in excess all of the hydrogens are taken…the reaction is what you would expect
BEWARE!!!
If you see the words equal molar, equimolar, or 1:1 ratio…that means the coefficients for BOTH reactants MUST be 1!!!

30. Double Replacement #4 (Acid Base neutralization)
Equal number of moles of sulfuric acid & sodium hydroxide react
H2SO4 + NaOH 
You would think you would get
H2SO4 + NaOH  Na2SO4 + H2O
But these are NOT in a 1 to 1 ratio when balanced
You get..
H2SO4 + NaOH  NaHSO4 + H2O

31. A salt is formed when an acid and a base are mixed and the acid releases H+ ions while the base releases OH- ions. This process is called hydrolysis. The pH of the salt depends on the strengths of the original acids and bases:

32. Acids Acids can be recognized because the start with H Examples HCl
H2SO4 HI

33. Acids
- Follow their own rules for naming. Most if not all acids contain H.
The binary acids always begin with the prefix hydro.
The stem comes from the other atom involved.
They always end in ic.

34. Complex Acids or Oxyacids- do not ever have a prefix.
Formed from polyatomic ions that have an O in them.
ate polyatomics form acids and their ending changes to ic
ite polyatomic ions end in ous

35. Rule #1 - naming acids
If the anion ends in –ide, the acid will be named…
Hydro (root) – ic acid
This is usually for H plus one element

36. For example HCl Hydrochloric acid HI Hydroiodic acid H2S
Hydrosulfuric acid

37. Rule #2 – naming acids
If you have an H plus an anion ending in –ate, the acid will be named…
(root) – ic acid

38. Examples
H2SO4
Sulfuric acid
HNO3
Nitric acid
H3PO4
Phosphoric acid

39. Rule # 3 – naming acids
If you have an H plus an anion ending in –ite, the acid will be named…
(root) – ous acid

40. Examples
H2SO3
Sulfurous acid
HNO2
Nitrous acid
H3PO3
Phosphorous acid

41. Remember…
ate  ic
ite - ous