Acids and Bases
Unit 13
Acids

1) Acids start with hydrogen, and some react
with active metals to liberate hydrogen gas.
Ba(s) + H2SO4(aq)
BaSO4 (aq) + H2(g)
Properties of Acids
2) Acids change the color of
dyes known as “acid-base
indicators”
 Acids turn litmus paper
turns red.
Properties of Acids
1)
Acids have a sour taste.
Properties of Acids
4)
Acids react with bases to
produce salt and water.
This is a neutralization
reaction.
Mg(OH)2 + HCl --> MgCl2 + HOH
5) Acids conduct electrical currents in
an aqueous solution. Acids are
electrolytes.

6) Acids produce hydrogen ions
when dissolved in water.
Bases
1) End with (OH) hydroxide
2) Change the color of acidbase indicators
litmus paper: red  blue
3) Bases feel slippery.
Properties of Bases
4)
5)
Bases react with acid to
produce salt and water.
This is called
neutralization reaction.
Bases are electrolytes.
What?

Bases produce hydroxide
ions when dissolved in water.
6)
Neutralization
Reactions
A
reaction between
traditional acids
(hydrodium ions) and
bases (hydroxide ions)
produces water and one
of a class of compounds
called salts
Acid Base Reactions



1. Salt- ionic compound composed of a
OH- from an Arrhenius base and an
H3O+ from an Arrhenius acid
2HNO3 + Ca(OH)2
Ca2+ (NO3-)2 + 2HOH
H2S + 2NaOH
Na2+ S2- + 2HOH
 Double Replacement
What is pH?
• A pH scale is how we measure how acidic or
basic something is.
• When we dissolve an acid in water, it ionizes and
produces excess Hydrogen Ions, H+
• pH is formally how we measure the activity of
those Hydrogen Ions in solutions.
Where Do Common Substances
Fall on the Scale?
pH is a range that
usually is expressed
as going from 0 to
14, though it can go
beyond that range.
Acid Rain
• Normal rain pH of 5.3
•Acid rain pH of 4.2-4.4
Acid Rain
• Man-Made Causes
– Burning of fossil fuels
(coal production – yucky!)
–carbon dioxide + water =>
carbonic acid
Traditional Acid
Definition: An Arrhenius
acid is a chemical compound
that increases the
concentration of hydrogen
ions, H+, in aqueous solution.
 HNO3 + H2O  H3O+ + NO3-
B. Acid- Base reactions- Arrhenius
(traditional) Acid – Base Reactions
• 1. An acid-base reaction occurs in
aqueous solution between a strong
Arrhenius acid that completely dissociates
to produce H3O+, and a strong Arrhenius
base that completely dissociates to
produce OH−
• HCl(aq) + NaOH(aq) NaCl(aq) + H2O(l)
c. Their water solutions
are known as aqueous
acids. All pure aqueous
acids are electroytes.
HNO3(l) + H2O(l)
HCl(g) + H2O(l)
H3O+(aq) + NO3−(aq)
H3O+(aq) + Cl−(aq)
Traditional Bases
 Arrhenius base is a substance
that contains hydroxide ions
(OH ) and dissociates to
produce hydroxide ions (OH-)
into solutions
 NaOH(s)
Na+(aq) + OH−(aq)