CHEM

1. pH - A Measure
of Acidity

2. pH- stands for
potential of
hydrogen. The pH of a solution is defined as the
negative logarithm of the hydrogen ion
concentration (in mol/L):
The Danish chemist Soren Sorensen in
1909 proposed a more practical
measure called pH.
H+ ion concentration is asked, just take the
antilog of the equation

3. The pH scale was developed in
an effort of compare the
strengths of acids and bases.
The pH scale runs from 0-14
pH < 7 are acidic
pH = 7 are neutral
pH > 7 are basic

4. What is the pH of a solution in which the
concentration of H+ 3.4 x 10-5? Is the substance
acidic, basic, or neutral?
Solution:
pH = -log [H+]
= -log[3.4 x 10-5]
pH = 4.47
ACIDIC
NOTE: For Significant figures for
Logarithms
The number of decimal places
in the log is equal to the number
of significant figures in the
original number.

5. TRY THIS!
The concentration of H+ ions in a bottle of table wine was
4.1 x 10-4 M right after the cork was removed. Only half of
the wine was consumed. The other half, after it had been
standing open to the air for a month, was found to have a
hydrogen ion concentration equal to 2.3 x 10-3 M. Calculate
the pH of the wine on these two occasions.

6. TRY THIS!
What is the hydrogen ion concentration if pH is 3.30?
H+= 10-3.30
H+= 5.0 x 10-4M

7. TRY THIS!
The pH of rainwater collected in a certain region of the
northeastern United States on a particular day was
5.23. Calculate the H+ ion concentration of the
rainwater.
H+= 10-5.23
H+= 5.9 x 10-6 M

8. 1. Calculate the pH values. Determine if each solution is
acidic, basic, or neutral.
A. [H+] = 1 x 10-7 M
B. [H+] = 6.7 x 10-11 M
C. [H+] = 0.1 M
D. [H+] = 8.54 x 10-9 M
2. What is the Hydrogen Ion Concentration if the pH
equals
8.75?

9. pOH - stands
for potential of
hydroxide ions.
pOH measures the amount of hydroxide ions
and measures basicity
pH + pOH = 14.00
If asked to calculate the OH- ion
concentration, we can take the antilog of
Equation:

10. TRY THIS!
What is the pOH of a solution that contains
3.5 x10-5 [OH-]? What is the substance’s pH?
pOH = -log [OH-]
pOH = -log [3.45 x10-5]
pOH = 4.46
pH + pOH = 14.00
= 14.00 – 4.46
pH = 9.54

11. TRY THIS!
In a NaOH solution [OH-] is 7.2 X 10 -5 M. Calculate
the pH of the solution.

12. TRY THIS!
The OH- ion concentration of a blood sample is
2.5 X 10 -7 M. What is the pH of the blood?
pOH = -log [OH-]
pOH = -log [2.5 X 10 -7]
pOH = 6.60
pH + pOH = 14.00
= 14.00 – 6.60
pH = 7.40

13. TRY THIS!
The pH of a sample of human blood was measured to
be 7.41 at 25⁰C. Calculate pOH, [H+], and [OH-] for
the sample.
OH- = 10-pOH
OH- = 10-6.59
OH = 2.6 X 10 -7 M
pH + pOH = 14.00
= 14.00 – 7.41
pOH = 6.59
H+ = 10-pH
H+ = 10-7.41
H+ = 3.9 X 10 -8M

14. Complete the following chart
pH H+ OH- pOH
3.00
1.0 X 10 -10 M
11.50
5.2 X 10 -11 M

15. Complete the following chart
pH H+ OH- pOH
3.00 1.0 X 10 -3 M 1.0 X 10 -11 M 11.00
10.00 1.0 X 10 -10 M 1.0 X 10 -4 M 4.00
2.50 3.2 X 10 -3 M 3.2 X 10 -12 M 11.50
3.72 1.9 X 10 -4 M 5.2 X 10 -11 M 10.28

16. Complete the following chart
pH H+ OH- pOH
1.83 X 10 -10 M
5.5
2.2 X 10 -11 M
8.55

17. Complete the following chart
pH H+ OH- pOH
9.738 1.83 X 10 -10 M 5.5 X 10 -5 M 4.26
5.5 3 X 10 -6 M 3 X 10 -9 M 8.5
3.34 4.6 X 10 -4 M 2.2 X 10 -11 M 10.66
5.45 3.5 X 10 -6 M 2.8 X 10 -9 M 8.55

18. Complete the following chart
pH H+ OH- pOH
3.00 1.0 X 10 -3 M 1.0 X 10 -11 M 11.00
10.00 1.0 X 10 -10 M 1.0 X 10 -4 M 4.00
2.50 3.2 X 10 -3 M 3.2 X 10 -12 M 11.50
3.72 1.9 X 10 -4 M 5.2 X 10 -11 M 10.28