Acids and Bases
What are examples of acids and bases and
what properties do they have?
Acids
Acids tend to have
hydrogen (H) in their
formula.
Examples:
H+ and Cl- produce HCl: hydrochloric acid
H+ and SO42- produce H2SO4: sulfuric acid
H+ and NO3- produce HNO3: nitric acid
H+ and PO43- produce H3PO4: phosphoric acid
Bases
Bases tend to have the
oxygen-hydrogen (OH)
group (called hydroxide)
in their formula.
Examples:
Na+ and OH- produce NaOH: sodium hydroxide
Ca2+ and OH- produce Ca(OH)2: calcium
hydroxide
NH4+ and OH- produce NH4OH: ammonium
hydroxide
Examples of Acids
Common acids:
Citrus juices (lemon,
orange…)
Carbonated beverages
(coca cola…)
Vinegar
Battery Acid
Examples of Bases
Common bases:
Household cleaners
Bleach
Stomach antacids
Some soaps
Baking Powder
Acid and Base Characteristics
1. Taste
Acids taste sour:
lemon juice (citric acid)
vinegar (acetic acid)
sour milk: (lactic acid)
aspirin (acetylsalicylic acid)
Bases taste bitter
Soap
Baking soda and water
Acid and Base Characteristics
2. “Indicator” colour change
An indicator is a substance
that changes colour when
added to an acid or a base.
Examples
Indicator
Litmus
Phenolphthalein
Methyl orange
Bromothymol blue
Acid
red
colourless
orange
yellow
Base
blue
pink
yellow
blue
Acid and Base Characteristics
3. Conductors
An electric current will pass through an acid
or a base solution.
Acid and Base Characteristics
4. Reaction with some metals
When acids react with some metals, they
produce hydrogen gas.
Bases do not react with these metals.
Acid and Base Characteristics
5. Reaction with carbonates and bicarbonates
When acids react with carbonates and
bicarbonates, they produce carbon dioxide
gas.
Acid and Base Characteristics
6. Feel of bases
Bases feel slippery: they dissolve fats and oils
on skin reducing friction.
Neutralization
When acids and bases are combined, they
“neutralize” each other.
The products are salt and water.
Example:
HCl + NaOH  NaCl + H2O