GRADE 11
CHEMISTRY
Solutions & Solubility
Class 13
pH (Power of Hydrogen)
• The concentration of H+ and OH-
ions in aqueous solutions are
frequently very small and
inconvenient to use
• pH is the negative logarithm of
the hydrogen ion concentration
pH = -log[H+] Søren Sørenson proposed
measuring concentrations of
acid/bases using pH
1
, pH = -log[H+]
pH = -log[H3O+]
pOH = -log[OH-]
[H+] = 10-pH
[OH-] = 10-pOH
• Distilled water at 25°C
[H3O+] = [OH-] = 1.0 x 10-7 mol/L
• At 25 °C
• pH < 7 is acidic
• pH = 7 is neutral
• pH > 7 is basic
pH + pOH = 14
2
, Checkpoint
Calculate the pH of a solution with [H3O+] of 3.8x10-3
mol/L.
Checkpoint
Calculate the pH of the solution that is formed by
diluting 50 mL of 0.025 mol/L hydrochloric acid to a
final volume of 1.0 L.
3
CHEMISTRY
Solutions & Solubility
Class 13
pH (Power of Hydrogen)
• The concentration of H+ and OH-
ions in aqueous solutions are
frequently very small and
inconvenient to use
• pH is the negative logarithm of
the hydrogen ion concentration
pH = -log[H+] Søren Sørenson proposed
measuring concentrations of
acid/bases using pH
1
, pH = -log[H+]
pH = -log[H3O+]
pOH = -log[OH-]
[H+] = 10-pH
[OH-] = 10-pOH
• Distilled water at 25°C
[H3O+] = [OH-] = 1.0 x 10-7 mol/L
• At 25 °C
• pH < 7 is acidic
• pH = 7 is neutral
• pH > 7 is basic
pH + pOH = 14
2
, Checkpoint
Calculate the pH of a solution with [H3O+] of 3.8x10-3
mol/L.
Checkpoint
Calculate the pH of the solution that is formed by
diluting 50 mL of 0.025 mol/L hydrochloric acid to a
final volume of 1.0 L.
3
