On this page
Understanding pH and Acid-Base Chemistry
Formula
pH is a logarithmic scale used to specify the acidity or basicity of an aqueous solution. Values below 7 indicate acidic solutions, 7 is neutral, and values above 7 indicate basic (alkaline) solutions. The pH scale is fundamental in chemistry, biology, medicine, and environmental science.
The pH value is calculated as the negative base-10 logarithm of the hydrogen ion activity: pH = -log10([H+]). Because the scale is logarithmic, each whole pH unit represents a tenfold change in hydrogen ion concentration. For example, a solution with pH 3 is ten times more acidic than one with pH 4.
Common use cases:
- Water quality testing
- Laboratory solution preparation
- Soil acidity analysis
Frequently Asked Questions
Dr. David Park
Applied Mathematician, PhD Mathematics
David holds a PhD in Applied Mathematics from MIT. He has published research on numerical methods and computational algorithms used in engineering and scientific calculators.
Was this calculator helpful?
People Also Use
Molarity Calculator
Calculate molarity (molar concentration) from solute mass, molar mass, and solution volume with this free chemistry tool.
Dilution Calculator
Calculate dilution volumes and concentrations using the C1V1 = C2V2 equation for laboratory solution preparation.
Ideal Gas Law
Solve the ideal gas law equation PV = nRT for pressure, volume, temperature, or moles with unit conversions.
Mole Calculator
Convert between moles, grams, and number of particles using molar mass and Avogadro's number.
Molecular Weight
Calculate the molecular weight and elemental composition of any chemical compound from its formula.
Solution Concentration
Calculate solution concentration in mass percent, ppm, and molality from solute and solvent amounts.
Boiling Point Elevation
Calculate the boiling point elevation of a solution using the ebullioscopic constant, molality, and van't Hoff factor.
Freezing Point Depression
Calculate freezing point depression using the cryoscopic constant, molality, and van't Hoff factor.