a. Examples of Bronsted-Lowry Acids.
NH4 -- ammonium ion.
HC2H3O2 -- acetic acid.
H2CO3 -- carbonic acid.
b. Examples of Bronsted-Lowry Bases.
Cl -- chloride ion.
NH3 -- ammonia.
Fe(OH)2 -- iron (II) hydroxide.
WEAK ACIDS/BASES VERSUS STRONG ACIDS/BASES
As discussed previously, we stated that acids, bases, and salts are ionic
compounds. Substances that break up into ions in solution are termed electrolytes
because the solution has the ability to conduct electrical current. A strong electrolyte
(acid or base) is a substance that exhibits a high degree of ionization, and a weak
electrolyte is a substance that only partially ionizes.
a. Hydrochloric (HCl), sulfuric (H2SO4), and nitric (HNO3) acids are strong acids
because they exhibit a high degree of ionization in aqueous solutions. Hydrobromic
(HBr), hydroiodic (HI), and perchloric (HClO4) acids are also considered strong acids.
All others are weak.
b. The alkaline metal (Group IA, i.e., lithium, sodium, potassium) hydroxides and
the alkaline earth (Group IIA, that is, magnesium, calcium, strontium,...) hydroxides are
strong bases. Other bases are weak ones.
c. Hydrogen and hydroxide only affect pH or pOH when in the ionized form.
When an acid ionizes, an equilibrium is established between the unionized acid
and its ions. This is indicated by double arrows or a doubled-headed arrow in an
equation, showing that the two reactions occur simultaneously. HA is used to represent
any acid made up of hydrogen and some anion.
HA <====> H + A