pH Calculator

The pH scale measures acidity or alkalinity of a solution on a scale of 0-14. This calculator converts between pH, pOH, hydrogen ion concentration [H+], and hydroxide ion concentration [OH-] using logarithmic relationships.

1. 1

   Select Calculation Mode

   Choose whether to calculate pH from [H+], [H+] from pH, or similar conversions for pOH

2. 2

   Enter Known Value

   Input the concentration (in moles per liter) or pH/pOH value

3. 3

   View Results

   See all related values: pH, pOH, [H+], and [OH-]

4. 4

   Check Solution Type

   Determine if the solution is acidic (pH < 7), neutral (pH = 7), or basic (pH > 7)

• 1

  Each pH unit represents a 10-fold change in hydrogen ion concentration

• 2

  Pure water at 25C has a pH of exactly 7 (neutral)

• 3

  Human blood pH is tightly regulated between 7.35 and 7.45

• 4

  Stomach acid has a pH around 1-2; bleach has a pH around 12-13

• 5

  pH + pOH = 14 only at 25C; this value changes with temperature

• Thinking pH 6 is only slightly more acidic than pH 7 (it's 10 times more acidic)

• Forgetting that the pH + pOH = 14 relationship only holds at 25C

• Using wrong units for concentration (must be moles per liter)

• Confusing strong acids/bases with weak ones in concentration calculations