1. Aim: What are acids and bases?
Do Now: List whatever you know about acids and bases.

2. Acids Acids can be strong or weak electrolytes in aqueous solutions.
Acids (ex: HCl) react with certain metals to produce H2(g).
Acids cause color changes in acid-base indicators:
Blue litmus paper turns red in an acid
Phenolphthalein is colorless in an acid
Acids have a sour taste
Table K has a list of Common Acids

3. Bases Bases can be strong or weak electrolytes in aqueous solutions
Bases cause color changes in acid-base indicators:
Red litmus paper turns blue in a base
Phenolphthalein is pink in a base
Bases feel slippery and taste bitter.
Table L has a list of Common Bases

4. Arrhenius Acid
An Arrhenius acid gives off H+ (hydrogen ions) in aqueous solutions.
Ex: HCl, HBr, H2SO4
The H+ in solution attaches to H2O to form H3O+ (hydronium ion).
HCl + H2O  H+ + Cl- + H2O  Cl- + H3O+

5. Arrhenius Base
An Arrhenius base has OH and give off OH- (hydroxide ions) in an aqueous solution.
Ex: NaOH, KOH, Ca(OH)2
NaOH  Na+ + OH-
Group 1 metals react with water to produce bases.
2Na(s) + 2H2O(l) 2 NaOH(aq) +H2(g)

6. Question 1 Which substance can be classified as an Arrhenius acid? HCl
NaCl
LiOH
KOH

7. Question 2 Which substance can be classified as an Arrhenius base? HCl
NaOH
LiNO3
KHCO3

8. Question 3
According to the Arrheneius theory, a substance that is classified as an acid will always yield
H+(aq)
NH+4(aq)
OH-(aq)
CO32-(aq)

9. Bronsted-Lowry Acids and Bases
An acid is an H+ donor(proton donor).
A base is an H+ acceptor (proton acceptor)
HCl(g) H2O(l)  H3O+(aq) Cl-(aq)
HCl is an acid because it donates an H+ to the H2O.
Accepts H+
ACID
BASE
Donates H+

10. Bronsted-Lowry Acids and Bases
NH3(aq) H2O(l)  NH4+(aq) + OH-(aq)
NH3 is a base because it accepts an H+ from the H2O.
Accepts H+
ACID
BASE
Donates H+

11. Bronsted-Lowry Acids and Bases
Water can either be a proton donor (acid) or a proton acceptor (base); water is amphoteric.

12. Question 4
According to the Bronsted-Lowry theory, a chloride ion (Cl-), acts as a base when it combines with
An OH- ion
A K+ ion
An H- ion
An H+ ion

13. Question 5 According to the Bronsted-Lowry theory, an acid is
A proton donor, only
A proton acceptor, only
A proton donor and a proton acceptor
Neither a proton donor nor a proton acceptor

14. Conjugate acids and bases
NH3(aq) H2O(l)  NH4+(aq) + OH-(aq)
BASE ACID CONJUGATE CONJUGATE
ACID BASE
A conjugate base is what is remained after the acid gives up H+.
A conjugate acid is what is formed when a base accepts a proton.

15. Question 6 In the reaction H2PO4- + H2O  H3PO4 + OH-
which pair represents an acid and its conjugate base?
H2O and H2PO4-
H2O and H3PO4
H3PO4 and OH-
H3PO4 and H2PO4-

16. Question 7 Given the reaction at equilibrium
HSO4- + H2O  H3O+ + SO42-
According to the Bronsted-Lowry theory, the two bases are
H2O and H3O+
H2O and SO42-
H3O+ and H2SO4-
H3O+ and SO42-

17. Summary Arrhenius Bronsted-Lowry Arrhenius Bronsted-Lowry
Acids
Bases
Arrhenius
Gives off H+ in in water
Bronsted-Lowry
H+ donor
Arrhenius
Gives of OH- in water
Bronsted-Lowry
H+ acceptor