1. Acids and Bases

2. Properties of Acids and Bases
Water soluble
Electrolyte
Sour
Bitter
Corrosive
Feels like water
Feels slippery, like soap/wax
Turns litmus paper red
Turns litmus paper blue
Neutralizes bases
Neutralizes acids
Reacts with active metals to form H2(g)

3. Svante Arrhenius Developed the Arrhenius acid-base theory
Acids produce H+ ions in solution
Must have at least 1 hydrogen
Ex. HCl, H2S, CH3COOH
Bases produce OH- ions in solution
Have OH-, ex. NaOH, or react with water to form OH-, ex. NH3

4. Svante Arrhenius
When acids or bases are dissolved in solution they undergo ionization and separate into their ions
NaOH  Na+ + OH-
HCl  H+ + Cl-

5. Hydronium
H+ ions in solution react with water to form H3O+, an ion called Hydronium
Small amounts of hydronium are also formed by water reacting with itself:
2 H2O ↔ H3O+ + OH-

6. Hydronium Hydronium in solution is the source of acid- base chemistry.
The amount present in water is pH-neutral
Higher concentrations of hydronium leads to acidity
Lower concentrations of hydronium leads to being a base

7. Strong Acids and Bases
When ionic acids and bases are dissolved in water they dissociate completely. Virtually every molecule will split into ions(99+%).
H2S  2 H+ + S2-
1 mol of H2S dissociates into 2 mol of H+ and 1 mol of S2-
These solutions are called strong acids and strong bases

8. Weak Acids and Bases
When covalent acids and bases are dissolved in water they only dissociate partially. Only some molecules will split into ions.
CH3COOH ↔ CH3COO- + H+
1 mol of CH3COOH dissociates into mol of CH3COO- and H, with mol of CH3COOH remaining
These solutions are called weak acids and weak bases
1.3%

9. Weak Acids and Bases STRONG ACID/BASE WEAK ACID/BASE Ionic Covalent
Complete dissociation
Partial dissociation
Better electrolytes (more ions)
Worse electrolytes (less ions)

10. Strength Vs. Concentration
H+ or OH- concentrations are affected by
Acid/Base Concentration: “How much acid/base is in this solution?”
Acid/Base strength: “How much of it split into ions?”

12. pH A simple measure of acidity, usually ranging from 0- 14
7 is neutral (pure water)
0 is very acidic
14 is very basic

13. pH
So why 0-14?
Most acids and bases have a hydronium concentration from 1.0x100 to 1.0x mol/L
They just used the exponents and dropped the negative sign!
1 pH difference is a 10x change in concentration of H3O+. 2 pH = 100x, 3 pH =1000x, etc.

14. pH pH = - log[H3O+] [H3O+] = 10-pH
Reminder: [Chemical] means concentration in mol/L

15. Measuring pH
Indicators are chemicals that change colour under certain pH
Phenolphthalein; colourless in acid, hot pink in base

16. Measuring pH
Digital pH meters have a glass electrode that changes in conductivity when it interacts with Hydronium. This lets it measure pH.