pH Calculator
Calculate pH from concentration or vice versa
Frequently Asked Questions
What is pH exactly?
pH is a measure of hydrogen ion concentration in a solution, calculated as pH = -log₁₀[H⁺]. It indicates how acidic or basic a solution is.
How do I calculate pH from concentration?
For strong acids: pH = -log₁₀[concentration]. For bases: pOH = -log₁₀[concentration], then pH = 14 – pOH.
What if I have a weak acid or base?
Weak acids/bases don’t fully dissociate. You need to use the dissociation constant (Ka/Kb) in calculations. This calculator assumes 100% dissociation for strong acids/bases.
Why does pH matter in real life?
pH affects everything from water treatment to skin care. Enzymes in our body work best at specific pH levels, and plants grow better in certain soil pH ranges.
What’s the difference between pH and pOH?
pH measures hydrogen ions (H⁺), while pOH measures hydroxide ions (OH⁻). They’re related by pH + pOH = 14 at 25°C.
How accurate is this calculator?
Results are accurate for strong acids and bases at concentrations above 1×10⁻⁶ M. For very dilute solutions or weak acids/bases, lab measurements are more precise.
Can I use this for buffer solutions?
This calculator doesn’t account for buffer capacity. For buffer solutions, use the Henderson-Hasselbalch equation: pH = pKa + log([A⁻]/[HA])
How does temperature affect pH?
Temperature changes can shift the equilibrium of water (Kw) and affect dissociation of acids/bases. This calculator assumes standard temperature (25°C).
What’s the pH of pure water?
Pure water has a pH of 7 at 25°C, but this can vary with temperature and impurities. Distilled water often reads slightly below 7 due to CO₂ absorption from air.
How to measure pH in practice?
Use pH paper for rough estimates, or a calibrated pH meter for precise measurements. For industrial applications, electronic pH sensors are typically used.