1. Acid and Bases: An Introduction

2. Properties of Acids Sour taste
Can produce H+ (hydrogen) ions (protons)
Change the color of litmus from blue to red
Reacts with metals such as Zn and Mg to produce H2 gas.
Ba(s) + H2SO4  BaSO4(aq) + H2(g)
Reacts with carbonates (CO32-)to produce CO2
NaHCO3(s) + CH3COOH(aq)  NaCH3COO(aq) + H2O(l) + CO2(g)
Acids conduct an electric current

3. Properties of Bases Bitter or caustic taste A slippery, soapy feeling
Can produce OH- (hydroxide) ions
Ability to change litmus from red to blue
Bases conduct an electric current
Bases react with acids to produce a salt and water. This is known as a neutralization reaction.
HCl + NaOH  NaCl + H2O
HCl + Mg(OH)2  MgCl2 + H2O
acid base salt water

4. Ions in Solution
Acidic solutions contains more hydrogen (H+) ions than hydroxide ions (OH-) pH < 7
Basic solutions contains more hydroxide ions (OH-) than hydrogen ions pH > 7
Neutral solutions contain an equal concentration of hydrogen and hydroxide ions pH = 7

5. Three Definitions of Acids/Bases
Type
Acid
Base
Arrhenius
H+ producer
OH-producer
Bronsted-Lowry
H+ donor
H+ acceptor
Lewis
Electron-pair acceptor
Electron-pair donor

6. Bronsted-Lowry Conjugate Acid/Base
HX(aq) + H2O(l) ⇆ H3O+(aq) + X-(aq)
acid base Conjugate Conjugate
Acid Base
Conjugate acid is the substance produced when a base accepts a hydrogen ion from an acid
Conjugate base is the substance that the acid donates a hydrogen ion to form a base

7. Bronsted-Lowry Conjugate Acid/Base
Conjugate acid-base pair consists of two substances related to each other by donating and accepting of a single hydrogen ion
NH3(aq) + H2O(l)  NH4+ (aq) + OH-(aq)
base acid conjugate conjugate
acid base

8. Practice: Conjugate Acid and Conjugate Base
HCO H2S ⇆ H2CO3 + HS-
H2PO4- + OH- ⇆ HPO42- + H2O
H2SO4 + NH3 ⇆ HSO NH4+
HC2H3O2 + H2O ⇆ H3O+ + C2H3O2-

9. Question Time Name the three models of acids/bases.
What is the Arrhenius model of acids/bases?
What is the Bronsted-Lowry Model of Acid bases?
What is a conjugate acid and a conjugate base?

10. Question Time
Identify the acid, base, conjugate acid, and conjugate base in the Bronsted-Lowry reactions.
NH3 + H2O ⇆ NH OH-
H2O + CH3NH2 ⇆ OH CH3NH3+
HF + H2O ⇆ H3O F-
HCOOH +CN- ⇆ HCOO- + HCN
NH4+ + CO32- ⇆ NH3 + HCO3-

11. Water in Acid/Base solutions
Water and other substances can act as both acids and bases and are said to be amphoteric
Hydronium ion = H3O+ = H+ (Remember H+ is a proton)
H2O(l) + H2O(l) ⇆ H3O+(aq) + OH-(aq)

12. Monoprotic and Polyprotic Acids
Monoprotic acid donates one hydrogen ion
Polyprotic acid donates more than one hydrogen ion

13. Question Time What is a Lewis acid? What is a Lewis base?
What is the H3O+ ion called?
What is the shorthand way to write H3O+?
What is amphoteric? Give an example.