1. Obj: Students will be able to describe an acid or a base.
Acids and Bases
Obj: Students will be able to describe an acid or a base.

2. Acids and Bases are Everywhere!
Every liquid you see will probably be either an acid or a base.
Exception: distilled water (just H2O)
Acids:
Amino acids in our bodies
Citric acids in fruits
Bases:
Baking soda mixed with water

3. Acids
A solution that can donate a hydrogen ion—a proton (H+)—to another substance.
general form is: HX
Ex. HCl, H2SO4, HF, HBr…
Generally the name “acid” is given to any substance that has a pH of less than 7.0
pH: general abbreviation for potential of Hydrogen
The more H+ ions, the stronger the acid will be.

4. Properties of Acids Taste sour (grapefruit, vinegar, limes, etc.)
React strongly with metals
Ex. when acids react with Mg, Zn, and Fe, hydrogen gas is produced. As a result, the metals seem to wear away.
“Corrosive”  they “eat away” other materials
Strong acids are dangerous and can burn your skin. (HCl, H2SO4, HF)
Litmus paper – turns RED
Video

6. Bases
A solution that can accept a hydrogen ion—a proton—from another substance.
generally the opposite of acids
Ionic compounds (compound with a positive or negative charge) that break apart to form a negatively charged hydroxide ion (OH-) in water.
Typically a base is any solution that has a pH greater than 7.0
The greater the concentration of OH- ions, the stronger the base will be.

8. Properties of Bases Taste very bitter (soaps, shampoos)
Feel slimy or slippery (washing your hands)
Can react violently with acids and cause burning on the skin
In solution (mixed with water), will conduct electricity
Litmus paper – turns BLUE

9. pH Scale Useful to identify a substance as acidic or basic.
0-4 strong acid
4.01—6.99 weak acid
7.00 = neutral
7.01—14 = base
= weak base
10.01—14 = strong base

10. Examples – Acidic or Basic?
Soil pH 5.7
Soft drinks pH 3.9
Baking soda pH 8.4
Milk pH 6.4
Vinegar pH 2.6
Blood pH 7.4
Bleach pH 11.5
Ammonia pH 12.5
Acidic
Acidic
Basic
Acidic
Acidic
Basic
Basic
Basic

11. Indicators
A special type of compound that changes color as the pH of a solution changes.
Can tell us the pH of a solution
Red cabbage juice
Litmus paper – most common indicator used by scientists
Acids turn litmus paper red
Bases turn litmus paper blue