Chemistry

  • Van't Hoff Equation Calculator
    Compute a new equilibrium constant K2 from K1, ΔH and two temperatures using the Van't Hoff equation: ln(K2/K1) = -(ΔH/R)(1/T2 - 1/T1).
  • Enthalpy of Reaction Calculator (Hess's Law)
    Calculate the enthalpy of reaction (ΔH) using Hess's Law from the standard enthalpies of formation of products and reactants. Free and instant.
  • First-Order Reaction Half-Life Calculator
    Calculate the half-life of a first-order reaction from its rate constant k using t½ = 0.693 / k. Fast, accurate chemistry kinetics tool.
  • Percent Dilution Calculator
    Calculate the final percent concentration after adding diluent. Uses C2 = C1·V1/(V1+V_added) to find diluted strength, total volume, and dilution factor.
  • pH Calculator for Strong & Weak Acids and Bases
    Calculate the pH and pOH of strong and weak acid or base solutions from concentration and Ka/Kb. Free chemistry pH calculator with worked examples.
  • pOH Calculator
    Free pOH calculator: find pOH from hydroxide ion concentration [OH⁻] or from pH using pOH = -log10[OH⁻] and pH + pOH = 14.
  • Ka, Kb, pKa, pKb Calculator
    Convert between Ka, Kb, pKa and pKb instantly. Enter any one value and get the other three using pKa = -log10(Ka) and pKa + pKb = 14 at 25°C.
  • Van't Hoff Factor Calculator
    Calculate the Van't Hoff factor (i) from observed freezing point depression, the cryoscopic constant Kf, and molality. Free chemistry tool with formula.
  • Freezing Point Depression Calculator
    Calculate freezing point depression (ΔTf = i·Kf·m) from the van 't Hoff factor, cryoscopic constant, and molality, plus the new freezing point.
  • Gay-Lussac's Law Calculator
    Free Gay-Lussac's Law calculator. Solve P1/T1 = P2/T2 for pressure or temperature at constant volume. Enter three values to find the fourth instantly.
  • Moles to Gas Volume at STP Calculator
    Convert moles of any ideal gas to volume at STP. Uses the molar volume of 22.414 L/mol. Fast, accurate chemistry calculator with worked examples.
  • Significant Figures Calculator
    Free significant figures calculator: count the sig figs in any number and round a value to a chosen number of significant digits instantly.
  • Equilibrium Concentration Calculator (ICE Table)
    Solve the ICE-table equilibrium expression Kc = x²/(C₀−x) for x. Get equilibrium concentrations and percent dissociation instantly.
  • Percent Yield from Grams Calculator
    Calculate percent yield from grams instantly. Enter actual and theoretical yield in grams to find your reaction's % yield using a simple formula.
  • A260/A280 Purity Ratio Calculator
    Calculate the A260/A280 absorbance ratio to assess DNA and RNA sample purity. Enter your spectrophotometer readings for an instant nucleic acid quality check.
  • Concentration from Absorbance Calculator
    Calculate solution concentration from absorbance using the Beer-Lambert law: c = A / (ε · l). Enter absorbance, molar absorptivity, and path length.
  • pH to H+ Concentration Calculator
    Convert a pH value to hydrogen ion concentration [H+] using [H+] = 10^(−pH). Also returns pOH and [OH−]. Fast, accurate chemistry tool.
  • Moles of Gas Calculator (PV = nRT)
    Calculate moles of an ideal gas from pressure, volume and temperature using PV = nRT. Enter P in atm, V in liters, T in kelvin to get n in moles.
  • pH Calculator from Concentration
    Calculate pH from hydrogen ion concentration [H+] using pH = -log10([H+]). Also returns pOH and [OH-]. Free, instant chemistry tool.
  • % w/v to mg/mL Calculator
    Convert percent weight/volume (% w/v) concentration to milligrams per milliliter (mg/mL) instantly. Uses mg/mL = %w/v × 10. Free pharmacy & lab tool.
  • Ideal Gas Law Calculator (PV = nRT)
    Solve the ideal gas law PV = nRT for pressure, volume, moles, or temperature. Enter any three values with flexible units (atm, L, mol, K) to find the fourth.
  • Liters to Moles Calculator
    Convert liters of gas to moles using the molar volume. At STP a gas occupies 22.4 L/mol, so n = V / 22.4. Fast, accurate chemistry conversion.
  • Significant Figures Arithmetic Calculator
    Add, subtract, multiply or divide two numbers and round to the correct significant figures. Supports scientific and e-notation with full sig-fig rules.
  • pH from pOH Calculator
    Convert pOH to pH instantly with pH = 14 − pOH at 25°C. Also shows [H⁺] and [OH⁻] ion concentrations for any solution.

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