pH Calculator - Calculate pH and pOH Online

Free online pH calculator to calculate pH and pOH values from concentration. Perfect for chemistry students and laboratory work.

Solution Information

mol/L

pH Results

Enter concentration and solution type to calculate pH

About pH Calculator

The pH Calculator helps you calculate pH and pOH values from the concentration of acids or bases in solution.

pH Scale:

  • 0-3: Very acidic (stomach acid, battery acid)
  • 3-6: Acidic (coffee, orange juice)
  • 6-7: Weakly acidic (milk, saliva)
  • 7: Neutral (pure water)
  • 7-8: Weakly basic (blood, seawater)
  • 8-11: Basic (soap, ammonia)
  • 11-14: Very basic (bleach, drain cleaner)

Formulas Used:

  • For Acids: pH = -log[H⁺]
  • For Bases: pOH = -log[OH⁻], pH = 14 - pOH
  • Relationship: pH + pOH = 14

Key Concepts:

  • pH measures hydrogen ion concentration
  • pOH measures hydroxide ion concentration
  • Lower pH = more acidic
  • Higher pH = more basic
  • pH 7 is neutral

Applications:

  • Chemistry laboratory work
  • Water quality testing
  • Food and beverage industry
  • Environmental monitoring
  • Medical diagnostics
  • Industrial processes

Important Notes:

  • This calculator assumes strong acids/bases
  • Weak acids/bases require different calculations
  • Temperature affects pH values
  • Ionic strength can influence results

Note: This calculator provides estimates for educational purposes. For precise measurements, use calibrated pH meters and consider all solution factors.

Frequently Asked Questions

What is pH?

pH is a measure of the acidity or basicity of a solution. It's defined as the negative logarithm of the hydrogen ion concentration: pH = -log[H⁺].

What's the difference between pH and pOH?

pH measures hydrogen ion concentration, while pOH measures hydroxide ion concentration. They are related by the equation: pH + pOH = 14.

How do I calculate pH from concentration?

For strong acids: pH = -log[H⁺]. For strong bases: pOH = -log[OH⁻], then pH = 14 - pOH. This calculator assumes strong acids and bases.

What does a pH of 7 mean?

A pH of 7 indicates a neutral solution, where the concentrations of H⁺ and OH⁻ ions are equal. Pure water has a pH of 7 at 25°C.

Can I use this calculator for weak acids and bases?

This calculator is designed for strong acids and bases. Weak acids and bases require more complex calculations involving equilibrium constants and dissociation.