Post on 02-Jan-2016
SC Physical Science Standard
PS-3.8Classify various solutions as acids or bases according to their physical properties, chemical properties (including neutralization and reaction with metals), generalized formulas, and pH (using pH meters, pH paper, and litmus paper).
Acids and Bases
Acids produce H+ in solutions
HCl H+(aq) + Cl- (aq)
Bases produce OH- in solutions
NaOH Na+(aq) + OH-
(aq)
H20
H2O
Determining pH
pH- a measurement of hydrogen ion concentrationpH scale ranges from 0 – 14pH of an acid is 0 – 7
Acids have more H+ than OH-.
The lower the pH the more acidic the solution.
pH of a base is 7 – 14Bases have less H+ than OH-.
The higher the pH the more basic the solution.
pH of neutral is 7Neutral has equal H+ and OH-.
Neutral is neither acid nor base.Water is neutral.
Determining pH
pH is tested for two ways:1. pH meter- gives a digital reading of the pH of a solution2. indicator- a compound that turns different colors based on the pH of the solution it is in (example: litmus paper, phenolphthalein)
Properties of Acids
-Produce H+ (H3O+) in solution
-Formulas start with H
- Taste sour
-Neutralize bases
-Corrosive to skin and tissue
-Acids turn litmus paper red
Corrosive to metals-react with metals to produce hydrogen gas
Are electrolytes in solution-conduct electricity
Properties of BasesProperties of Bases
-Produce OH- in solution
-Have OH in formula
-Taste bitter
- Neutralize acids
-Corrosive to skin and body tissues
-Turn Litmus paper blue
Common Bases
Mg(OH)2
Magnesium hydroxideantacids
NH3 Ammonia cleaners; fertilizer
Ca(OH)2 Calcium Hydroxidealso in fertilizers (lime)