“Acids, Bases, and Salts”. Acids-Bases n OBJECTIVES: –Define the properties of acids and bases.
Chapter 2.2 - Acids and Bases
description
Transcript of Chapter 2.2 - Acids and Bases
Chapter 2.2 - Acids and Bases
p. 42-43 in Prentice Hall Biology, Miller and Levine
Double, double toil and trouble; Fire burn, and cauldron bubble…
What just happened with the witches and their pink potion?
Indicators
Chemicals that respond to a change in H ion concentration
Change color depending on whether substance is an acid or a base
Examples: litmus paper phenolphthalein
Ions
What is an ion?
Answer: positively or negatively charged atom
What is an Acid?
A compound that forms H+ ions in a solution
Example: Hydrochloric acid produced by stomach to digest food (HCl), carbonic acid in carbonated pop (HCO3), sulfuric acid in car batteries (H2SO4)
Characteristics of Acids
Contains Hydrogen (H+)
Turns litmus paper red
Tastes sour
Dissolves metal
What is a Base?
A compound that forms hydroxide ions (OH-) in a solution
Example: Lye
Characteristics of Bases
Contains Hydroxide
Turns litmus paper blue
Tastes bitter
Feels slippery
How Do We Measure Acids and Bases?
The pH scale
What does pH stand for
Power of Hydrogen
Scale ranges from 0 to 14
pH Scale: Acids
Acids have a pH below 7
Strong acids range from 1 to 3
Strong acid example: HCl
pH Scale: Bases
Bases have a pH above 7
Strong bases range from 11 to 14
Strong base example: lye, bleach, drano, Sodium hydroxide (NaOH)
pH Scale
pH increases tenfold
Water, Acids and Bases
A water molecule can react to form ions
Water is Neutral
Why is pure water considered “neutral”?
Pure water pH = 7
Number of positive hydrogen ions equal to negative hydroxide ions produced