The Acid/Base Square:
This square helps convert between [H+], pH, pOH, and [OH-]
Example Calculations:
a) What is the pH of a 0.050 M HNO3?
Since we are dealing with an acid, we know the [H+]…
pH = -log[H+]
pH = -log[0.050]
pH = 1.3 = acidic
b) Find the hydroxide ion concentration of 3.010-2 M HCl.
[H+][OH-] = 1.0  10-14
[3.0  10-2][OH-] = 1.0  10-14
[OH-] = 3.3  10-13 M = acidic
c) What is the molarity of HBr in a solution that has a pOH of 9.6?
pH + pOH = 14
H+ = 10-pH
pH + 9.6 = 14
H+ = 10-4.4
pH = 4.4
[H+] = 3.98  10-5 M HBr = acidic
pH Practice
1. Draw the pH scale, labeled 0-14. Identify where a solution is acidic, basic and neutral.
2. Calculate the pH of the following solutions. Identify the solution as acidic, basic or neutral.
a) [H+] = 1.00 x 10-3 M
b) [H+] = 1.00 x 10-10 M
c) [H+] = 6.59 x 10-10 M
d) [H+] = 9.47 x 10-3 M
3. Find the pH of each of the following solutions and identify them as acidic, basic or neutral.
a) pOH = 2.00
b) pOH = 8.00
c) pOH = 1.263
d) pOH = 9.714
4. Calculate the pH of the following solutions and identify them as acidic, basic or neutral.
a) [OH-] = 1.00 x 10-9 M
b) [OH-] = 1.00 x 10-3 M
c) [OH-] = 9.56 x 10-4 M
d) [OH-] = 7.49 x 10-10 M
5. Find the pH and the [H+] of each of the following solutions and identify them as acidic, basic or
neutral.
a) pOH = 9.50
b) pOH = 3.65
c) pOH = 12.63
d) pOH = 1.14
pH, pOH, [H+], and [OH-] Calculations WS
1.
2.
Calculate the pH and pOH for the following solutions:
a) [H+] = 1.0 x 10-5 M
d) [OH-] = 3.0 x 10-8 M
b) [H+] = 2.5 x 10-2 M
e) [OH-] = 7.5 x 10-3 M
c) [H+] = 1.2 x 10-14 M
f) [OH-] = 6.0 M
Calculate the [H+] and [OH-] for the following solutions:
a) pOH = 2.60
d) pH = 3
b) pOH = 5.63
e) pH = 7.51
c) pOH = 1.13
f) pH = 0.03
Directions: Fill in the missing information in the table below.
pH
[H+]
pOH
[OH-]
3.78
3.89 x 10-4 M
5.19
4.88 x 10-6 M
8.46
8.45 x 10-13 M
2.14
2.31 x 10-11 M
10.91
7.49 x 10-6 M
9.94
2.57 x 10-8 M
4.16
1.06 x 10-1 M
3.82
8.53 x 10-7 M
7.05
4.73 x 10-10 M
1.33
9.87 x 10-3 M
11.68
9.22 x 10-8 M
12.24
5.39 x 10-12 M
Acid or Base?