What temperature is assumed for the calculations?

The calculator assumes a standard temperature of 25 °C, where the water autoionization constant (Kw) is 1.0 x 10^-14.

How does the proton/hydroxide count affect the pH calculation?

It accounts for polyprotic strong acids (like H2SO4, n=2) or bases (like Ba(OH)2, n=2) that release multiple ions per molecule, multiplying the effective concentration.

Can this calculator be used for weak acids or weak bases?

No, this calculator is designed for strong acids and bases that dissociate completely; it does not use Ka or Kb values.

What units are used for concentration and volume?

Concentration is measured in moles per liter (mol/L or M), and volumes for dilution are measured in milliliters (mL).

How does dilution affect the pH of a strong acid?

Adding water decreases the concentration of H+ ions, moving the pH closer to neutral 7.

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pH Calculator

Convert between pH, [H+], pOH and [OH-], or compute pH from a strong acid/base concentration, including dilution.

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pH 3 → all four quantities

pH = 3 corresponds to [H+] = 1×10⁻³ mol/L, pOH = 11, [OH-] = 1×10⁻¹¹ mol/L (acidic).

{"result":"pH = 3 → [H+] = 0.001 mol/L, pOH = 11, [OH-] = 1e-11 mol/L (acidic).","metadata":{"result":{"pH":3,"hplus":0.001,"pOH":11,"ohminus":1e-11,"nature":"acidic"}}}

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9 options

SettingsAdjust formats, ranges, numbers, and modes.9

Calculation ModeselectOptionalInput QuantityselectOptionalWhich of the four quantities you are entering.Input ValuenumberOptionalNumeric value of the selected input quantity.Acid/BaseselectOptionalProton/Hydroxide Count (n)numberOptionalNumber of H+ per acid molecule (HCl=1, H2SO4=2) or OH- per base unit (NaOH=1, Ba(OH)2=2).Concentration C (mol/L)numberOptionalMolar concentration of the acid or base (mol/L).Initial Volume V1 (mL)numberOptionalInitial volume of the acid/base solution before dilution.Added Water V2 (mL)numberOptionalVolume of pure water added to dilute the solution.Decimal PlacesnumberOptional

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pH Calculator

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1. Converting pH to Ion Concentrations

2. Calculating pH of a Strong Diprotic Acid

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3. Diluting a Strong Base Solution