130 THE THEORY OF IONIZATION
PROBLEMS- Acetic acid in 0.1 molal solution is 1.4 per cent ionized.
Find the value of the ionization constant K.
HAc ^ H+ + Ac"
[H+] X [Ac"
[HAc] = K - Find the percentage ionization of acetic acid in molal
solution. Take the value of the ionization constant as
0.000018 and solve the quadratic equation by the method
of approximation. - What is the concentration of hydrogen ions in a 0.1
molal solution of acetic acid? - What is the concentration of hydrogen ions in a solu-
tion containing in a liter 0.1 mole of acetic acid and 0.1 mole
of NaAc? Assume as an approximation that the salt is 100
per cent ionized. - For the sake of showing the different effects of a neu-
tral salt of a strong acid upon the ionization of the acid, find
first the ionization constant of nitric acid if it is 90 per cent
ionized in 0.1 molal solution. Then using the constant thus
found calculate the hydrogen-ion concentration in a solution
containing, in 1 liter, 0.1 mole of HN0 3 and 0.1 mole of KN0 3.
Assume in this calculation that the law of molecular con-
centration holds accurately. The result shows that the
effect of a neutral salt of a strong acid upon the ionization
of the acid is not marked as it is in the similar case of a weak
acid. As a matter of fact, the actual effect is even less than
that calculated according to the law. - The ionization constant of ammonium hydroxide is
0.000018. (a) Find the concentration of OH" ions in a
molal solution of NH4OH. (6) Find the concentration of
OH~ ions in a molal solution of NH 4 0H which contains
also 0.5 mole of NH 4 C1 per liter, assuming the latter to be
completely ionized. - What is the ionization constant of hydrocyanic acid
if the ionization in 0.1 N solution is 0.01 per cent? - What is the hydrogen-ion concentration in a solution
containing, in 1 liter, 0.1 mole of HCN and 0.1 mole of KCN,
assuming the latter to be 100 per cent ionized?