Use this chemistry calculator to reproduce a named relationship with explicit quantities and units for study, laboratory planning, or an independent numerical check.

First pKa

Required number input.

Second pKa

Required number input.

Compute the isoelectric point as the average of the two relevant pKa values. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Isoelectric point pI

The resulting isoelectric point pi returned as a number.

• Concentration-based acid–base formulas usually approximate activities and may assume a fixed water ion product. Ionic strength, temperature, polyprotic equilibria, dilution volume, and activity coefficients can materially shift pH and speciation.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check units and significant figures, compare the result with limiting cases, and use measured or source-specific constants where available. Laboratory, safety, and regulatory decisions require validated methods and appropriate uncertainty analysis.

• Triprotic Amphiprotic Species pH Estimate

  Estimate the pH of either intermediate amphiprotic form of a triprotic acid from the average of its adjacent pKa values.

• Isotopic Abundance Calculator

  Solve the two-isotope percent abundances that produce a known weighted-average atomic mass.

• Activation Energy Two-Temperature

  Compute activation energy in J/mol from rate constants at two temperatures as R times ln(k2/k1) over one over T1 minus one over T2.