Calculating pH, pOH
pH = -log10(H3O+)
pOH = -log10(OH-)
Relationship between pH and pOH
pH + pOH = 14
Finding [H3O+], [OH-] from pH, pOH
[H3O+] = 10-pH
[OH-] = 10-pOH
pH + pOH = 14
Acidic
Neutral
Basic
pH/pOH Calculations
• What is the pH of a solution containing a
hydrogen ion concentration of 3.0x10-4M?
pH = -log [H+]
pH = -log (3.0x10-4M)
pH = 3.52
pH/pOH Calculations
• What is the pOH of a solution containing a
hydrogen ion concentration of 3.0x10-4M?
pH = -log [H+]
pH = -log (3.0x10-4M)
pH = 3.52
14 = pH + pOH
14 = 3.52 + pOH
10.48 = pOH
pH/pOH Calculations
• What is the hydroxide ion concentration of
a solution containing a hydrogen ion
concentration of 3.0x10-4M?
[OH] x [H+] = 1.0x10-14
[OH] x (3.0x10-4M) = 1.0x10-14
[OH] = 3.33x10-11M
pH/pOH Calculations
• A solution has a pH of 3.7. What is the
pOH of this solution?
pH + pOH = 14
3.7 + pOH = 14
pOH = 10.3
pH/pOH Calculations
• A solution has a pH of 6.0. What is the
hydrogen ion concentration of this
solution?
[H] = 10-pH
[H] = 10-6.0
[H] = 1.0x10-6M
pH/pOH Calculations
• A solution has a pOH of 8.0. What is the
hydroxide ion concentration of this
solution?
[OH] = 10-pH
[OH] = 10-8.0
[OH] = 1.0x10-8M
pH/pOH Calculations
• A solution has a pH of 6.0. What is the
hydroxide ion concentration of this
solution?
pH + pOH = 14
[OH] = 10-8.0
6.0 + pOH = 14
[OH] = 10-8.0
pOH = 8.0
[OH] = 1.0x10-8M