Download unit 11 notes special substances

Special Substances
IV. Strength of conjugates
 The stronger the acid or base is, the
weaker its conjugate base.
 For example, HCl is a strong acid so
its conjugate base, Cl- , is a weak
base.
V. Special Substances
 A. Some substances can be either an
acid or a base depending on the
substance it is with. These
substances are called amphoteric.
1. Must have hydrogen to act as acid
2. Can be a compound or ion.
3. Examples: water, HCO3-
VI. Anhydrides: oxides that create
acid or base in water
 1. Metal oxides create bases in water
(hydroxides)
 Na2O in water creates NaOH
 2. Nonmetal oxides create acids in water
 NO2 in water creates HNO3
 SO2 in water creates H2SO3
(components of acid rain)
VI. Neutralization Reactions
 A. Neutralization occurs when the hydrogen
(hydronium) ions of an acid react completely
with the hydroxide ions of a base to form
water molecules.
 B. The products of neutralization are always
water and a salt.
 1. A salt is composed of the cation from a
base and the anion from an acid. (Front half
can’t be hydrogen, back half can’t be
hydroxide or oxide.)
 2. Example: HCl + NaOH → NaCl + H2O
VII. Ionization constant of water (Kw)
 A. H2O + H2O → H3O+ + OH B. Concentration of the two ions at room
temperature in pure water are each 1 x 10-7 M
 C. The product of the two equals 1 x 10-14. This
product is constant at room temp and is given the
symbol Kw.
 Kw = [H3O+][OH-] = 1 x 10-14
 D. If one of the ion concentrations are known,
the other may be calculated.
E. Examples
 1. If the hydronium ion concentration is 1.0 x 10-4 M, what is
the concentration of the hydroxide ion?
1 x 10-14 = 1.0 x 10-10 M
1.0 x 10-4
 2. Determine the hydronium ion concentration in a 3.0 x 10-2
M HNO3 solution.
In a strong acid: #H (concentration) = [H+] (or [H3O+])
[H+] = 1(3.0 x 10-2) = 3.0 x 10-2 M
 3. Determine the hydronium and hydroxide ion
concentrations in a 1.0 x 10-4 M Ca(OH)2 solution.
In a strong base: #OH (concentration) = [OH-]
[OH-] = 2(1.0 x 10-4) = 2.0 x 10-4 M
[H3O+] = 1 x 10-14 = 5.0 x 10-11 M
2.0 x 10-4