pH Calculator
Calculate pH, pOH, and ion concentrations from hydrogen ion concentration or pH value with an interactive pH scale visualization.
Examples:
Pure water: 1.0e-7
Lemon juice: 1.0e-2
Vinegar: 6.3e-3
Baking soda: 2.0e-9
Ammonia: 5.6e-12
How to use pH Calculator
- Choose calculation mode: [H+] to pH or pH to [H+].
- Enter your hydrogen ion concentration (e.g., 1.0e-7) or pH value.
- Click Calculate to see pH, pOH, concentrations, and acidity classification.
- View the colored pH scale showing exactly where your solution falls.
What is pH Calculator?
The pH Calculator performs acid-base chemistry calculations using the fundamental relationships: pH = -log[H+] and pOH = 14 - pH (at 25C). You can input either hydrogen ion concentration in mol/L (supports scientific notation like 1.0e-7) or a pH value, and the tool calculates all related values including hydroxide concentration [OH-] via the ion product of water (Kw = 1 x 10^-14). The interactive pH scale shows exactly where your solution falls from strongly acidic (0) to strongly basic (14).
FAQ
- What does pH measure?
- pH measures the acidity or basicity of an aqueous solution on a scale of 0 to 14. It is defined as the negative logarithm (base 10) of the hydrogen ion concentration: pH = -log[H+]. A pH of 7 is neutral, below 7 is acidic, and above 7 is basic (alkaline).
- What scientific notation formats can I use?
- You can enter concentrations in standard decimal form (e.g., 0.0000001) or scientific notation (e.g., 1.0e-7 or 1e-7). The tool auto-detects the format. Common concentrations: pure water = 1.0e-7, lemon juice = 1.0e-2, ammonia = 5.6e-12.
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