Examples
of Acids
HCl
HNO3
HC2H3O2
H2SO4
H3PO4
Examples of
Bases
Acids
Bases
Taste sour
pH less than 7
conduct electricity
react with carbonates to produce CO2
react with active metals to produce
hydrogen
Increase H+ ion concentration in
solution
Do not feel slippery
Turn litmus paper red
React with bases to destroy their
properties
Taste Bitter
pH greater than 7
conduct electricity
do not react with carbonates
do not react with active metals
Increase OH- ion concentration in
solution
Feel slippery
Turn litmus paper blue
React with acids to destroy their
properties
Reaction of an acid with a base (neutralization) always produces a salt and water:
Acid
Base
Salt
HCl (aq)
+
NaOH(aq)
à
NaCl(aq)
+
H2SO4(aq)
+
Ca(OH)2(aq) à
CaSO4(aq)
+
HNO3(aq)
+
KOH(aq)
à
KNO3(aq)
+
Water
H 2O
2H2O
H 2O
Reaction of an acid with an active metal:
Metal
Acid
Zn(s)
+
2HCl(aq)
Mg(s)
+
2HNO3 aq)
à
à
Salt
ZnCl2(aq)
+
Mg(NO3)2(aq) +
Hydrogen gas
H2(g)
H2(g)
Reaction of an acid with a carbonate:
Acid
2HCl(aq)
+
H2SO4(aq)
+
à
à
Salt
2NaCl(aq)
MgSO4(aq)
water
H 2O +
H 2O +
(
Carbonate
Na2CO3(aq)
MgCO3(aq)
+
+
Carbon dioxide gas
CO2(g)
CO2(g)
NaOH
KOH
Mg(OH)2
Ca(OH)2
NH4OH
Acids and Bases are Everywhere!
Most liquids have characteristics that are either acidic or basic. Svante Arrhenius came up with a definition for acids and
bases in 1887. When something is dissolved in water that releases excess hydrogen ions, he saw that it had all the
characteristics of an acid. When something dissolved in water that released excess hydroxide (OH-) ions, he saw that it had
all the characteristics of a base.
Pure water (distilled water) will naturally have a very small amount of it’s molecules split up into H+ ions and
2H2O --> H3O+ + OH-
OH- ions.
So when something dissolves into water that adds hydrogen ions, it will become acidic.
HCl -->
H+ +
Cl-
And when something dissolves into water that adds hydroxide ions, it will become basic (alkaline).
NaOH
-->
Na+
+
OH-
The pH scale measures the amount of H+ ions in a solution. The pH scale is an inverse scale. This means that the higher the
number, the less acidic it is. The pH scale is also logarithmic. This means that a change from a pH of 7 to a pH of 6 is 10
times more acidic. A change from a pH of 7 to 5 is 100 times more acidic.