(4)
Weak acid and strong base.
H2CO3 + NaOH -----> NaHCO3 + H2O
NOTE: These four reactions result in three types of salts. Reactions (1) and (2) result
in neutral salts (that is, in terms of pH), which means a solution of the salt
in water will be a neutral solution. Reactions such as (3) result in acidic salts,
which produce acidic solutions. Reaction (4) results in basic salts, which produce
basic solutions.
c. Determination of Salt Type. To determine the type of salt from a chemical
formula, we employ the following steps:
(1) The first element comes from a base. Determine which base and
whether it is weak or strong.
(2) The remainder of the formula comes from the acid. Determine which
acid and whether it is weak or strong.
(3) By knowing the strengths of the acid and base that formed the salt,
the salt type can be assigned. Table 2-2 is a summary of salt types resulting from
d. Example. Al2(SO4)3.
(1) The first element, aluminum, comes from the base Al(OH)3. Since it has
a valence of +3, it is a weak base.
(2)
The sulfate radical comes from H2SO4, sulfuric acid, which is a strong
acid.
(3) This compound is an acidic salt since it is the product of a reaction
between a strong acid and a weak base.
MD0803
2-18