1. Unit A 2.4 Acids and Bases

2. Acids & Bases
Acids - compounds that dissolve in water to form a solution , pH<7
Bases - compounds that dissolve in water to form a solutions, pH>7
pH - indicates whether a substance is an acid or a base
measures the [H+]
Buffer - substance that keeps the pH at a constant, despite the addition of acids or bases
.i.e. your stomach

3. Acids & Bases
Indicators - chemicals that determine if a solution is an acid or a base
.I.e. Litmus paper, derived from Lichen
ACID BASE
RED BLUE
Acid -> Red stays red, blue turns red
Base -> Blue stays blue, red turns blue
Neutral -> Blue stays blue, red stays red

4. Acids & Bases
Universal Indicators - change color at a variety of pH levels
pH scale - measure of acidity = [H+]
one interval increase on the pH scale = 10x more acidic or basic

5. pH Scale

6. Properties of Acids & Bases
Property
Acid
Base
Taste
Sour
Bitter
Touch
Wet
Slippery
Reaction with metals
Metal corrodes H2 bubbles form
No reaction
Litmus indicator
Red
Blue
Electrical conductivity (in solution)
conductive
Conductive
pH of solution
<7
>7

7. Naming Acids Recognizing Acids
H appears on the left side of the formula
hydrochloric acid - HCl(aq)
-COOH - organic acid group found in the chemical formula
ethanoic acid - CH3COOH(aq)

8. Naming Acids Naming according to IUPAC
State of the compound followed by the name
HCl(aq) - aqueous hydrogen chloride
H2SO4(aq) - aqueous hydrogen sulfate
Other naming systems prior to IUPAC
For acids containing H and a non-metallic element
start with “hydro”, end with “ic”
HCl(aq) - hydrochloric acid
HF(aq) - hydrofluoric acid

9. Naming Acids For acids containing oxygen name is based on the anion
if the anion ends in “ate”, then the acid will end in “ic”
H2SO4(aq) - Sulfate -> derived from sulfur, then sulfuric acid
H3PO4(aq) - Phosphate -> derived form phosphorous, then phosphoric acid
HNO3(aq) - Nitrate -> derived from nitrogen, then nitric acid
if the anion ends in “ite”, then the acid will end in “ous”
H2SO3(aq) - Sulfite -> derived from sulfur, then sulfurous acid
HNO2(aq) - Nitrite -> derived from nitrogen, then nitrous acid

10. Recognizing Bases OH- with a metal or ammonium = base
NaOH - sodium hydroxide
Other bases are difficult to identify & will be studied in more advanced chemistry

11. Neutralization
Reactions of acids and bases together to cancel out each others properties

12. Acid Rain (Precipitation)
Oxides of carbon, nitrogen and sulfur produced from burning organic materials react with water in the air to form acid rain.

13. Acid Precipitation

15. Homework:
Read Science 10 Text p.62 – 69 & 70-75
WB pg ALL
Section Review text pg A