Neutralization Calculations:

1

• Neutralization Calculations

5.0mL of 0.10M NaOH is mixed with 5.0mL of 0.50M
HCl.
eg

• Write the net ionic equation for this
  neutralization reaction.

HCl(aq) NaOH(aq) ? NaCl(aq) H2O(l)
net ionic
H(aq) OH-(aq) ? H2O(l)
or
H3O(aq) OH-(aq) ? 2 H2O(l)

• Calculate the net concentration of H3O. (not
  all the H3O is neutralized)

H3O(aq) OH-(aq) ? 2 H2O(l)
0.0025mol 0.0005mol
There is an excess of H3O of 0.0020 mol.
2

• Calculate the pH of the final solution.

pH -log H3O
(pOH -log OH-)

• pH -log (0.20)

pH - (-0.699)
pH 0.70
Where H3O 10 x
Note
log H3O x
If H3O 1 x 10 -5
eg
then log H3O -5
And -log H3O 5 pH
3
Calculate H3O in a solution that has pH 2.54.
eg
pH -log H3O
-pH log H3O
antilog (-pH) H3O

• H3O antilog (-2.54)

H3O 2.9 x 10-3 M
4
H gt OH-
Note If
Acidic
H lt OH-
Basic
H OH-
Neutral
pH lt 7
Acidic
_at_ 25?C If
pH 7
Neutral
pH gt 7
Basic
pOH lt 7
Basic
pOH 7
Neutral
pOH gt 7
Acidic
And
pH pOH 14.00
5
Note for pH and pOH values only digits after
the decimal are significant.
H3O
pH 8.60
2.5 x 10-9 M
(2 sig. fig.)
H3O
pH 10.000
1.00 x 10-10 M
(3 sig. fig.)
H3O
pH 7.0
1 x 10-7 M
(1 sig. fig.)
H3O
pH 2.521
3.01 x 10-3 M
(3 sig. fig.)