1. Acids and Bases

2. Properties of Acids
Produce H+ (as H3O+) ions in water (the hydronium ion is a hydrogen ion attached to a water molecule)
Taste sour
Corrode metals
Good Electrolytes
React with bases to form a salt and water
pH is less than 7
Turns blue litmus paper to red “Blue to Red A-CID”

3. Properties of Bases Generally produce OH- ions in water
Taste bitter, chalky
Are electrolytes
Feel soapy, slippery
React with acids to form salts and water
pH greater than 7
Turns red litmus paper to blue “Basic Blue”

4. Naming Acids
Binary Acid – An acid that contains only two elements, one of which is hydrogen and one which is more electronegative.
HF – Hydrofluoric acid
HCl – Hydrochloric acid
Oxyacid – An acid that has hydrogen, oxygen, and a third element that is usually a non-metal
HClO4 – Perchloric acid
HNO2 – Nitrous acid
H2CO3 – Carbonic acid

5. Arrhenius Definition
Acid - Substances in water that increase the concentration of hydrogen ions (H+).
Base - Substances in water that increase concentration of hydroxide ions (OH-).
Problem – many bases do not actually contain hydroxides

6. Bronsted-Lowry Definition
Acid - neutral molecule, anion, or cation that donates a proton.
Base - neutral molecule, anion, or cation that accepts a proton.
HA + :B  HB :A-
HCl + H2O  H3O Cl-
Acid Base Conj Acid Conj Base

7. Conjugate Acid Base Pairs
Conjugate Base - The species remaining after an acid has transferred its proton.
Conjugate Acid - The species produced after base has accepted a proton.
HA & :A- - conjugate acid/base pair
:A- - conjugate base of acid HA
:B & HB+ - conjugate acid/base pair
HB+ - conjugate acid of base :B

8. Examples of Bronsted-Lowry Acid Base Systems
Note: Water can act as acid or base
Acid Base Conjugate Acid Conjugate Base
HCl + H2O  H3O Cl-
H2PO4- + H2O  H3O HPO42-
NH4+ + H2O  H3O NH3
Base Acid Conjugate Acid Conjugate Base :NH H2O  NH OH-
PO H2O  HPO OH-

9. Diprotic and Triprotic Acids (Polyprotic)
Sulfuric Acid can donate two protons per molecule
Phosphoric acid can donate three protons per molecule
H3PO4 + H2O  H3O+ + H2PO4-
H2PO4- +H2O  H3O+ + HPO42-
HPO42- +H2O  H3O+ + PO43-

10. G.N. Lewis Definition Lewis Acid - an electron pair acceptor
Base - an electron pair donor

11. Common Strong Acids/Bases
Hydrochloric Acid
Nitric Acid
Sulfuric Acid
Perchloric Acid
Strong Bases
Sodium Hydroxide
Potassium Hydroxide
*Barium Hydroxide
*Calcium Hydroxide
*While strong bases they are not very soluble

12. Acid Strength Strong Acid Weak Acid
Transfers all of its protons to water
Transfers only a small fraction of its protons to water
Completely Ionized
Partly Ionized
Strong Electrolyte
Weak Electrolyte
Conjugate Base is Weaker
Conjugate Base is Stronger
As acid strength decreases, base strength increases
The stronger the acid, the weaker its conjugate base
The weaker the acid, the stronger its conjugate base

13. Base Strength Strong Base Weak Base All molecules accept a proton
Fraction of molecules accept a proton
Completely Ionized
Partly Ionized
Strong Electrolyte
Weak Electrolyte
Conjugate Acid is Weaker
Conjugate Acid is Stronger
As base strength decreases, acid strength increases
The stronger the base, the weaker its conjugate acid
The weaker the base, the stronger its conjugate acid

14. Salts & Neutralization
A salt is the neutralization product of an acid and a base.
The anion comes from the acid and the cation from the base.
Examples
HCl NaOH  NaCl + H2O.
H2SO4 + 2 KOH  K2SO4 + H2O.

15. The pH Scale
pH [H3O+ ] [OH- ] pOH

16. pH and acidity
Acidity or Acid Strength depends on Hydronium Ion Concentration [H3O+]
The pH system is a logarithmic representation of the Hydrogen Ion concentration (or OH-) as a means of avoiding using large numbers and powers.
pH = - log [H3O+]
pOH = - log [OH-]
3. What is the pH of a solution if the [H3O+] is 3.4 x 10-5 M?
pH = -log [H3O+]
= -log(3.4 x 10-5)
= 4.47

17. pH and acidity Kw = [H3O+] [OH-] = 1.0 x10-14 In pure water
pH + pOH = 14

18. Indicators

19. pH and acidity
The pH values of several common substances are shown at the right.
Many common foods are weak acids
Some medicines and many household cleaners are bases.