1. (Acids/Bases) What to understand?
pH – The pH of a solution is a measure of the concentration of Hydrogen ions H+ in that solution.
pH Scale
Hydrogen ion is a hydrogen atom that has lost its only electron.
Acids releases hydrogen ions (H+ ) in water solutions.
Bases releases hydroxide ions (OH- )in solutions.

2. Acids and Bases
Definitions of Acids & Bases - There are three ways to define acids & bases:
1. Arrhenius- production of H3O+ and OH- *this is the general definition that we will use for now….
2. Brønsted-Lowry- H+ donors & acceptors
3. Lewis- e- pair donators & acceptors

3. The Arrhenius definition:
An acid is a substance that dissociates in water to produce hydrogen ions ( H+ )
A base is a substance that dissociates in water to produce hydroxide ions (OH- )
Examples:
Hydrochloric acid sodium hydroxide
Nitric acid potassium hydroxide
Acetic acid magnesium hydroxide
Sulfuric acid calcium hydroxide
Carbonic acid barium hydroxide
Phosphoric acid

4. HCl (aq) + H2O(l) → H3O+ (aq) + Cl- (aq)
The Bronsted-Lowry Definition:
An acid is any substance that can donate H+ ions.
A base is any substance that can accept H+ ions.
According to the Bronsted and Lowry, a molecule of HCl does not simple dissociate in water in a hydrogen ion (H+) and a chloride ion (Cl- ). Rather, it reacts with water to produce a hydronium ion (H3O+) and a chloride ion.
HCl (aq) + H2O(l) → H3O+ (aq) + Cl- (aq)

5. Properties of Acids
sour taste- remember that acetic acid (vinegar) & citric acid are sour, don’t EVER taste anything in the lab
change pH paper- changes pH paper red or orange
rxn w/ phenolphthalein - none
reactivity with metals- metals react with metals by single replacement reactions to yield H2(g) and a salt
ex. Ba(s) + H2SO4(aq)  BaSO4(aq) + H2(g)

6. react w/ bases by neutralization reactions- to make salts & water by a double replacement, the products are not sour, do not change pH paper, and do not react w/ metals
ex. HCl(aq) + NaOH(aq)  HOH(l) + NaCl(aq)
CaO + 2HCl -> HOH + CaCl2
are electrolytes- b/c they form ions in aqueous solution, they are electrolytes (conduct electricity)
feeling- like water on unbroken skin, they sting on cuts

7. Properties of Bases-
rxn w/ phenolphthalein – colorless to pinbitter taste- Have any of you ever tasted soap?
change pH paper- bases change pH paper to blue
bases are slippery
react w/ acids by neutralization rxns- to yield salts & water by DR rxns
are electrolytes- b/c they dissociate to form ions, they too conduct electrolytes

8. pH Scale

9. Acid Deposition
SO2 is release into the atmosphere when coal and petroleum products are burned. Volcanic eruptions.
In the atmosphere, sulfur dioxide can react with water to produce sulfurous acid.
Both Sulfurous and sulfuric acid can fall out of the sky in liquid form as rain, sleet, or snow. Acid Deposition

10. Acid Rain When rain has a pH lower than 5.6. It is considered acidic
Effects: 1. Damage buildings and statues.
2. Makes lakes and streams unsuitable
for life.
Equation:
H2SO4 + CaCO3 → CaSO4 + H2O + CO2

11. Work on the following…
Checking Up p.210 (1-4)
Chem To Go p.212 (1-10)

12. Homework:
Answer Acids and Bases Study Guide. (see copy)