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Acids and
Bases
Notes and Questions
Ms. Haapala
Acids and Bases
Standard 5
Acids, bases, and salts are three
classes of compounds that form ions in
water solutions.
a. Students know the observable properties
of acids, bases, and salt solutions.
b. Students know acids are hydrogen-iondonating and bases are hydrogen-ionaccepting substances.
What is an acid? What is a base?
Talk to your neighbor and come up with
some examples:
1.
2.
Acid
________
________
Base
________
________
Common Acids

Acids:
1. Milk (slightly acidic)
2. Lemon, orange, etc (citric acid)
3. Vinegar
4. Stomach acid (HCl)
5. Acid Rain
6. Carbon Dioxide
Common Bases

Bases
1. Soap
2. Blood
3. Antacids
4. Baking Soda
5. Ammonia
6. Egg Whites
Properties of Acids


Taste: sour
Acids react with metal to form
hydrogen gas
– Video: Hyperlink for drop on acid on a
metal (see the gas formed)

Acidic Solutions conduct electricity
Properties of Bases
 Taste:
bitter
 Slippery
to the touch
 Bases and metals do NOT
react (nothing happens)
 Basic Solutions conduct
electricity
Litmus Paper

Litmus paper changes color to
distinguish solutions of acids and
bases.
 Acidic
solution – contains
more (H+) than (OH-)
 Basic
solution – contains
more (OH-) than (H+)
Litmus Paper
 Aqueous
solutions of acids
cause blue litmus paper to
turn pink.
 Aqueous
solutions of bases
cause red litmus paper to
turn blue.
Check for understanding

Decide if each example is or describes a
property of an acid or a base:
– Milk
– Turns blue litmus paper red
– Orange Juice
– Does NOT react with metals
– Tastes bitter
Water: Neutral
 Pure
water is neutral
 produces
equal # of hydrogen
ions (H+) and hydroxide ions
(OH-).
Video clip – properties of acids and bases
Acids and Bases
Standard 5
Acids, bases, and salts are three
classes of compounds that form
ions in water solutions.
d. Students know how to use the pH
scale to characterize acid and base
solutions.
What is the pH scale?




The pH scale is related to the
concentration of H+ ions which
determines how acidic or basic a
solution is.
Acidic
Neutral
Basic
Below 7
7
Above 7
pH scale
The pH of a solution is the negative logarithm of the
hydrogen ion concentration:
pH = - log [H+]


The lower concentration of H+, the
higher the pH (more basic)
The higher the concentration of H+,
the lower the pH (more acidic)
Check for understanding



What type of a solution has a pH of
8?
Does an acidic solution have a high
or low concentration of H+ ions?
What is the pH of water? What
does that make it?