1. Introduction to Acids and Bases

2. What are Acids and Bases?
There are two models:
Arrhenius (He came first and most often this is what is used as a definition for an acid or a base)
Bronsted-Lowry (they expanded they definitions to include substances that didn’t necessarrily meet the requirements of Arrehenius’ definition)

3. Acid: Increases H+ concentration in water.
Arrhenius
Acid: Increases H+ concentration in water.
The individual ions will separate!
Examples: HCl H+ + Cl-
HNO H+ + NO3-
H2SO H+ + SO4 2-
H2O

4. Base: Increases OH- concentration in water.
Arrhenius
Base: Increases OH- concentration in water.
The individual ions will separate!
Examples: NaOH Na+ + OH-
LiOH Li+ + OH-
Ca(OH) Ca2+ + 2OH-
H2O
Note: Contain OH- as anion in formula!

5. In a formula:
Acids will start with an H
Bases will end in an OH

6. Bronsted-Lowry
Acid: A substance that can DONATE a proton (H+) to another substance.
Base: A substance that ACCEPTS a proton (H+) from another substance.
Examples: NH HCl  NH4 + Cl-
CO HBr  HCO Br-

7. Bronsted-Lowry
Acids further grouped by # of H+ they can donate:
Monoprotic: HF, HCl, HNO3 , HClO3
Diprotic: H2SO3 , H2SO4 , H2CO3
Triprotic: H3PO4

8. Comparison Arrhenius Acid HCl HBr H2SO4 H3PO4 etc. Bronsted-Lowry Acid
Same as above

9. Comparison Arrhenius Base NaOH LiOH Ca(OH)2 Bronsted-Lowry Base
NH3 , OH - , HCO3 -

10. These are called conjugate acids and bases.
A better way to identify acids and bases is by LOOKING FOR PROTON ACCEPTORS AND DONATORS
NH3 + H2S  NH SH-
These are called conjugate acids and bases.

11. Conjugate Acids and Bases
(Note: Conjugates are on the product side, the right side, of the chem. eqn.)
Conjugate Acid:
-the substance formed when a base gains a hydrogen ion.
NH3 + H2S  NH SH-
conj. acid

12. Conjugate Acids and Bases
Conjugate Base:
-the substance formed when an acid loses a hydrogen ion.
NH3 + H2S  NH SH-
conj. base

13. Conjugate Acids and Bases
Conjugate Acid-Base Pair:
consists of two substances related by the loss or gain of a single hydrogen ion
NH3 + H2S  NH SH-
Base Acid Conj Conj Acid Base

14. Conjugate Acids and Bases
Try These: Label acid, base, conjugate acid and conjugate base.
HBr H2O H3O Br-
NOTE: H3O+ called “hydronium ion”

15. Conjugate Acids and Bases
Try These: Label acid, base, conjugate acid and conjugate base.
HCl OH HOH Cl-

16. Conjugate Acids and Bases
Try These: Label acid, base, conjugate acid and conjugate base.
CO H2O HCO OH -

17. Conjugate Acids and Bases
Try These: Label acid, base, conjugate acid and conjugate base.
CO H2O HCO OH -
NOTE: H2O can act as an acid or a base. Substances that can do this called ‘amphoteric’!

18. To Summarize… • Acids donate a proton, become conjugate bases.
• Bases accept a proton, become conjugate acids.

19. Check Your Understanding
Write the conjugate acid to the following bases:
SO4 2-
Cl -
NO2 -
HCO3 -

20. Check Your Understanding
Write the conjugate acid to the following bases:
SO4 2- HSO4 -
Cl - HCl
NO2 - HNO3
HCO3 - H2CO3

21. Check Your Understanding
Write the conjugate base to the following acids:
HNO3
H2SO3
NH3
HCO3 -

22. Check Your Understanding
Write the conjugate base to the following acids:
HNO3 NO3 -
H2SO3 HSO3 -
NH3 NH2 -
HCO3 - CO3 2-

23. Your Turn