Chemistry Tools

Free chemistry calculators that run entirely in your browser — empirical and molecular formula, percent composition, molality, mole fraction, normality, ppm↔molarity, serial dilution, buffer pH (Henderson-Hasselbalch), Nernst, equilibrium constant, colligative properties, Gibbs free energy and Arrhenius. No sign-up, nothing uploaded.

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Empirical & Molecular Formula Calculator

Find the empirical formula from element masses or percent composition, then the molecular formula from a known molar mass.

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Percent Composition Calculator

Enter a chemical formula to get the molar mass and the mass percent of every element, with support for parentheses and hydrates.

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PPM ⇄ Molarity Converter

Convert between parts per million and molarity for a solution using its molar mass and density, with mg/L and µg/mL output.

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Buffer pH Calculator (Henderson-Hasselbalch)

Calculate buffer pH, the conjugate base to acid ratio, or pKa using the Henderson-Hasselbalch equation.

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Molality Calculator

Calculate molality from solute and solvent masses, or convert between molality and molarity using the solution density.

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Nernst Equation Calculator

Compute cell potential, standard potential or reaction quotient from the Nernst equation, with a spontaneity check.

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Serial Dilution Calculator

Plan a serial dilution: concentration at each tube plus the transfer and diluent volumes for any fold and step count.

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Average Atomic Mass Calculator

Compute the average atomic mass from isotope masses and abundances, or solve a missing percent abundance so the abundances sum to 100%.

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Colligative Properties Calculator

Freezing-point depression, boiling-point elevation and osmotic pressure from molality, van't Hoff factor i and solvent Kf/Kb constants.

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Equilibrium Constant Kc & Reaction Quotient Calculator

Compute the equilibrium constant Kc or reaction quotient Q from concentrations and coefficients, and see which way the reaction shifts.

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Mole Fraction & Mole Percent Calculator

Find mole fraction, mole percent and mass fraction of each component from moles, or from mass and molar mass, entirely in your browser.

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Normality & Equivalent Weight Calculator

Convert between molarity and normality, or find normality from mass, using the n-factor and equivalent weight (Mr ÷ n-factor).

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Gibbs Free Energy Calculator (ΔG = ΔH − TΔS)

Solve Gibbs free energy ΔG = ΔH − TΔS for any variable, judge spontaneity, and link ΔG° to the equilibrium constant K.

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Arrhenius Equation Calculator

Arrhenius solver: find k, A, activation energy Ea or T at one point, or get Ea from two rate constants at two temperatures.

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