Acidity (pH) Converter
Convert between pH, pOH, H+ and OH- concentrations
Conversion Formula:
pOH = 14 - pH
Common Acidity Conversions
Common pH Values
| Substance | Typical pH | Category | [H+] mol/L |
|---|---|---|---|
| Battery Acid | 0.0 | Strong Acid | 1.0 × 10⁰ |
| Stomach Acid | 1.0 - 2.0 | Strong Acid | 1.0 × 10⁻¹ |
| Lemon Juice | 2.0 - 3.0 | Weak Acid | 1.0 × 10⁻² |
| Vinegar | 2.2 - 2.9 | Weak Acid | 5.0 × 10⁻³ |
| Orange Juice | 3.0 - 4.0 | Weak Acid | 1.0 × 10⁻³ |
| Coffee | 4.5 - 5.5 | Weak Acid | 3.2 × 10⁻⁵ |
| Pure Water | 7.0 | Neutral | 1.0 × 10⁻⁷ |
| Human Blood | 7.35 - 7.45 | Weak Base | 4.0 × 10⁻⁸ |
| Baking Soda | 8.0 - 9.0 | Weak Base | 1.0 × 10⁻⁸ |
| Soap | 9.0 - 10.0 | Weak Base | 1.0 × 10⁻⁹ |
| Ammonia | 11.0 - 11.5 | Strong Base | 1.0 × 10⁻¹¹ |
| Bleach | 12.5 - 13.5 | Strong Base | 3.0 × 10⁻¹³ |
| Lye (Sodium Hydroxide) | 14.0 | Strong Base | 1.0 × 10⁻¹⁴ |
pH Facts
- The pH scale was developed by Danish chemist Søren Peder Lauritz Sørensen in 1909.
- The "p" in pH stands for "potenz" (German for power), and the "H" is for hydrogen ion concentration.
- Each whole pH value below 7 is ten times more acidic than the next higher value. For example, pH 4 is ten times more acidic than pH 5.
- Similarly, each whole pH value above 7 is ten times more alkaline than the next lower value.
- Small changes in human blood pH can be fatal - blood pH needs to stay between 7.35 and 7.45.
Applications of pH Measurement
Soil pH affects nutrient availability to plants. Most plants prefer slightly acidic soils (pH 6.0-6.8) where nutrients like nitrogen, phosphorus, and potassium are most available.
Blood pH is tightly regulated. Conditions like acidosis (low pH) or alkalosis (high pH) can indicate serious medical issues. Urine pH can help diagnose kidney and urinary tract conditions.
pH affects food preservation, taste, and safety. Low pH foods (below 4.6) inhibit bacterial growth and are easier to preserve. Many cooking reactions are pH-dependent.
Water pH is critical for aquatic life. Most freshwater ecosystems thrive at pH 6.5-8.2. Acid rain and pollution can lower water pH, harming aquatic organisms.
History of pH Measurement
The concept of pH was first introduced by Danish chemist Søren Peter Lauritz Sørensen in 1909 while working at the Carlsberg Laboratory in Copenhagen. The original definition was the negative logarithm of the hydrogen ion concentration.
Early pH measurements were conducted using indicator dyes like litmus paper. The first electrode for pH measurement was developed in the 1930s, making accurate electronic pH meters possible.
Modern pH measurement techniques include precise digital pH meters with temperature compensation, colorimetric methods, and specialized pH-sensitive electrodes for various applications.
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pH Scale Visualized
pH Scale Visualization
Similar to: Pure Water
At exactly pH 7, water has equal concentrations of H+ and OH- ions (10^-7 mol/L each), making it perfectly neutral.
Effect on human tissue: Generally safe for human contact
Ionic Visualization
Click "Show Ions" to visualize pH at molecular level
Visual Scale:
(pH 0-6)
(pH 7)
(pH 8-14)
Ion Concentration:
[H+]:1.00e-7 mol/L
[OH-]:1.00e-7 mol/L
In water at 25°C: [H+] × [OH-] = 10-14
pH = -log10[H+]
pOH = -log10[OH-]
pH + pOH = 14
Common Applications:
- Water quality testing
- Food and beverage production
- Agriculture (soil testing)
- Medical diagnostics
- Swimming pool maintenance
- Environmental monitoring
About the Acidity (pH) Converter
Convert between pH, pOH, H+ and OH- concentrations All conversions run instantly in your browser and nothing you enter is sent to a server.
Common Conversion Formulas
| From | To | Formula |
|---|---|---|
| pH | Hydrogen ion concentration [H⁺] | pH = -log₁₀[H⁺] |
| pH | pOH | pH + pOH = 14 (at 25°C) |
| Hydrogen ion concentration [H⁺] | pH | [H⁺] = 10^(-pH) mol/L |