Balancing Redox Reactions
Balance a redox equation by entering its reactants and products, including ionic charges. The calculator finds coefficients that conserve both atoms and charge.
Chemistry Calculators: Gas Laws, Stoichiometry and Reactions
Use these chemistry calculators to solve problems involving reactions, gases, solutions and molecular quantities. The Chemical Equation Balancer and Balancing Redox Reactions tools help you check reaction equations, while Convert Atoms to Moles and Atomic Mass support stoichiometry work. Explore the Ideal Gas Law, Boyle’s Law, Charles' Law and Dalton’s Law calculators to find relationships between pressure, volume and temperature.For solution and lab work, try C1V1 = C2V2 for dilutions, Acetate Buffer Composition for buffer preparation, or Beer–Lambert Law for absorbance calculations. These tools are useful for students, teachers and lab professionals who want to check their calculations.
Reactions 31
Solubility Product
Calculate the solubility product (Ksp) of a sparingly soluble salt from its molar solubility. Enter the solubility, its unit, and the cation and anion coefficients from the formula AaBb.
Estimation of Calcium
Enter the volume and normality of KMnO₄ used in the titration and the sample weight. The calculator returns a value labeled calcium percentage; check the formula against your laboratory method before interpreting it as a true calcium content.
TLC Rf
Enter the distance your TLC spot traveled and the distance the solvent front traveled, and this calculator returns the retention factor Rf with an interpretation of the separation quality.
Chemical Equation Balancer
Enter a chemical equation using = between reactants and products to find balancing coefficients. The calculator shows a balanced equation when it can process the formulas.
Atom Economy
Enter the coefficients and molar masses of all reactants in the balanced equation plus the coefficient and molar mass of your desired product to get the atom economy, the by-product mass per 100 g of reactants, and an interpretation.
Precipitation Prediction
Enter the cation and anion concentrations, their stoichiometric exponents, and the solubility product Ksp to find out whether a precipitate forms when two solutions are mixed. The calculator compares the ion product Qsp with Ksp and predicts precipitation instantly.
Antoine Equation
Calculate the vapor pressure of a pure liquid at a given temperature, or the boiling temperature at a given pressure, using Antoine coefficients A, B and C. Works with mmHg, kPa, bar and other pressure units.
Arrhenius Equation
Calculate a reaction rate constant with the Arrhenius equation. Enter the frequency factor, activation energy in kJ/mol, and temperature in kelvin.
Chemical Oxygen Demand
Calculate the chemical oxygen demand (COD) of a water sample from a dichromate back-titration. Enter the blank and sample FAS titration volumes, the titrant normality, and the sample volume to get the result in mg/L as O₂.
Chromatography Resolution
Enter the retention times and widths of two chromatographic peaks to calculate their resolution (Rs) and find out whether they are baseline-separated. Supports widths measured at the baseline or at half height.
Kirchhoff's Law of Thermochemistry
Convert a reaction enthalpy from one temperature to another using Kirchhoff's law. Enter the known enthalpy at a reference temperature, the target temperature, and the summed heat capacities of reactants and products.
Langmuir Adsorption Isotherm
Calculate fractional surface coverage θ and adsorbed amount q from the Langmuir isotherm. Enter the equilibrium concentration or pressure, the affinity constant KL, and optionally the maximum capacity qmax.
Standard Cell Potential
Enter the standard reduction potentials of the cathode and anode to get the standard cell potential E°cell, the spontaneity verdict, and the free energy change ΔG° per mole of electrons.
Reaction Half-Life
Calculate the half-life of a zero-, first- or second-order chemical reaction from the rate constant k and, where needed, the initial concentration. Results are shown in seconds and in your chosen time unit.
Van 't Hoff Equation
This calculator uses the Van 't Hoff equation to predict how an equilibrium constant changes with temperature. Enter K at a reference temperature, the standard reaction enthalpy, and the two temperatures to get K at the new temperature, the change factor, and ΔG°.
Calorimetry
Calculate the heat absorbed or released by a substance using Q = mcΔT. Enter the mass, specific heat capacity and the initial and final temperatures to get Q in joules, kilojoules and kilocalories.
Electrochemical Equilibrium Constant
Enter the standard cell potential E°cell, the number of electrons transferred n, and the temperature to find the equilibrium constant K of a redox reaction from ΔG° = −nFE° = −RT ln K.
Hess's Law
Calculate the enthalpy change of any reaction using Hess's law: combine known reactions with multipliers, or build the target reaction from standard formation enthalpies. Enter your values and get the result in kJ/mol and kcal/mol.
Equilibrium Constant
Calculate the equilibrium constant Kc from the equilibrium concentrations of reactants and products. Enter the stoichiometric coefficients and concentrations from your balanced equation to get Kc, 1/Kc, and whether the reaction is product- or reactant-favoured.
Reaction Order from Initial Rates
Enter the concentration and initial rate measured in each experiment, and this calculator determines the reaction order n, the rate constant k, and the full rate law using the method of initial rates.
Reaction Rate Law
Calculate the instantaneous reaction rate from the rate law v = k[A]^a[B]^b… Enter the rate constant, the concentration and order of each reactant, and get the rate, overall order and correct unit of k.
Clausius–Clapeyron
Estimate the vapor pressure of a liquid at any temperature from one known pressure–temperature pair and the enthalpy of vaporization, using the integrated Clausius–Clapeyron equation. Enter the known conditions, the target temperature, and ΔHvap.
Nernst Equation
Calculate the cell potential of an electrochemical cell under nonstandard conditions using the Nernst equation. Enter the standard potential E°, temperature, electrons transferred n, and reaction quotient Q.
Standard Entropy of Reaction
Calculate the standard entropy of reaction ΔS° from tabulated standard molar entropies. Enter the stoichiometric coefficient and S° of each reactant and product, pick a unit, and get ΔS° with a full breakdown.
Electrolysis
Calculate the mass deposited or produced in an electrolysis cell using Faraday's law. Enter the current, time, molar mass, and electrons transferred per formula unit to get charge, moles, and deposited mass.
Gibbs Free Energy
Calculate the Gibbs free energy change (ΔG) from enthalpy (ΔH), entropy (ΔS), and temperature, and instantly see whether the reaction is spontaneous under those conditions.
Kp to Kc
Convert an equilibrium constant between its pressure-based form (Kp) and concentration-based form (Kc). Enter the known constant, the temperature, and the change in moles of gas to get the result instantly.
pH
Calculate the pH and pOH of a solution from its hydrogen ion (H⁺) or hydroxide ion (OH⁻) concentration. Enter the molar concentration and an optional temperature to get pH, pOH and pKw.
Radioactive Decay
Calculate how much of a radioactive isotope remains after any time. Enter the initial amount or activity, the half-life, and the elapsed time to get the remaining amount, decay constant, and number of half-lives.
Titration
Calculate the unknown concentration of an acid or base from titration data. Enter the concentration and volume of the known solution, the volume of the unknown solution, and the reaction ratio.
Stoichiometry 21
C1V1 = C2V2
Find the volume of stock solution needed for a dilution. Enter the stock concentration, desired concentration, and desired final volume.
Convert Atoms to Moles
Convert a number of atoms into moles using Avogadro’s number. Enter a positive value in the Number of Atoms field to see the result in mol.
Mass Spectrometry m/z
Calculate the mass-to-charge ratio (m/z) of an ion from its neutral mass, charge number and adduct mass. Handles protonated, sodiated, ammoniated and multiply charged ions.
Water Hardness
Enter the measured calcium and magnesium concentrations and this water hardness calculator converts them to total hardness in mg/L as CaCO₃, classifies the water from soft to very hard, and shows the result in grains per gallon, German and French degrees.
Kohlrausch's Law
Calculate the limiting molar conductivity of any electrolyte at infinite dilution from its ionic conductivities and stoichiometric coefficients, using Kohlrausch's law of independent ion migration.
Molecular Mass (GMV Law)
Estimate a gas’s molar mass from its density relative to hydrogen. Enter the Density of Gas and Density of Hydrogen in g/L to calculate vapour density and molecular mass.
Debye–Hückel Activity Coefficient
Estimate the activity coefficient of an ion in aqueous solution using the Debye–Hückel limiting law, extended equation, or Davies equation. Enter the ionic strength, ion charge, and temperature to get γ and log₁₀ γ.
Raoult's Law
Calculate the total vapor pressure and vapor-phase composition of an ideal two-component liquid mixture using Raoult's law. Enter the mole fractions and the pure vapor pressures of both components.
Avogadro's Number
Estimate Avogadro’s number from the number of particles in a crystal unit cell, molar mass, density, and unit cell volume. Enter all four values in the units shown.
Empirical Formula
Enter the mass percentages or gram amounts of each element in a compound and instantly get its empirical formula, mole ratios, and the molar mass of the simplest formula.
Molecular Weight
Find molar mass from a chemical formula and see each element’s contribution. Optionally enter a sample mass to calculate moles and the number of molecules or formula units.
Molar Conductivity
Calculate the molar conductivity (Λm) of an electrolyte solution from its measured conductivity κ and molar concentration c. Enter both values with their units and get results in S·cm²/mol and S·m²/mol.
Molarity
Calculate the molarity (molar concentration) of a solution from the solute mass and molar mass, or directly from moles, and the total solution volume. Results are given in mol/L.
Normality
Calculate the normality (equivalent concentration) of a solution from its molarity, or from the mass and molar mass of the solute. Enter the equivalence factor and volume to get N in eq/L.
Percent Composition from Formula
Enter a chemical formula such as C6H12O6, Ca(OH)2 or CuSO4·5H2O and get the molar mass plus the mass percent of every element in the compound. Optionally override the atomic masses used.
Atomic Mass
Estimate an isotope’s atomic mass from its numbers of protons and neutrons. Enter the two counts to get an approximate result in atomic mass units (amu).
Percent Yield
Enter the actual yield you obtained and the theoretical yield from stoichiometry to instantly calculate the percent yield of your reaction, plus the difference between the two values. Supports g, mg, kg, lb and oz.
Boiling Point Elevation
Calculate the boiling point elevation of a solution from molality, the ebullioscopic constant Kb, and the van 't Hoff factor. Enter the pure solvent's boiling point to get the new boiling point in °C and °F.
Freezing Point Depression
Calculate the freezing point of a solution from molality, the cryoscopic constant (Kf), and the van 't Hoff factor. Enter your values to get the depression ΔTf and the new freezing point in °C and °F.
Molality
Calculate the molality of a solution in mol/kg. Enter the solute by mass or moles, plus the mass of the solvent, and get moles of solute and molality instantly.
Limiting Reactant
Enter the balanced-equation coefficients and available moles of two reactants to find which one is limiting, the maximum product yield, and how much excess reactant is left over.
Gases 13
Mean Free Path
Calculate the mean free path of gas molecules from temperature, pressure, and collision diameter. Enter the gas conditions in any common unit and get λ in nm, µm, mm, or m.
Gas Density
Calculate the density of any gas from its absolute pressure, temperature, and molar mass using the ideal gas law. Enter values in kPa, Pa, bar, atm, psi, or mmHg and °C, K, or °F — the result is shown in kg/m³, g/L, and lb/ft³.
Ideal Gas Law
Use pressure, temperature, volume, and moles of gas to solve the ideal gas law for one unknown. Enter the three known values in kPa, K, L, and mol.
Boyle’s Law
Use Boyle’s law to find a gas’s initial or final pressure or volume. Choose the unknown and enter the other three values, assuming constant temperature.
Molecular Speed of a Gas
Calculate the root-mean-square, mean, and most probable speeds of gas molecules from the temperature and molar mass, plus the average translational energy per mole, using kinetic theory formulas.
Dalton’s Law
Enter the moles of each gas, the temperature in kelvin, and the volume in liters to calculate mixture pressure. A unit-conversion error currently makes the displayed result 1,000 times too low.
Henry's Law
Calculate how much gas dissolves in a liquid at a given partial pressure using Henry's law. Enter the pressure and Henry's law constant to get the dissolved concentration, or solve for the pressure instead.
Gay-Lussac's Law
Calculate how gas pressure changes with temperature in a sealed, rigid container using Gay-Lussac's law. Enter the initial pressure and temperature plus one final value to find the other.
Charles' Law
Calculate the initial or final volume or temperature of a gas using Charles’ law. Select the value to find, then enter the other values at constant pressure.
Avogadro's Law
Calculate the missing volume or amount of gas using Avogadro's law. Enter the initial volume and amount, plus the new amount or new volume, and get the result with full steps.
Combined Gas Law
Find an unknown initial or final pressure, volume, or temperature using the combined gas law. Select the value to calculate, then enter the other five values.
Van der Waals Equation
Calculate the real-gas pressure from the Van der Waals equation. Enter the amount of gas, volume, temperature and the constants a and b to get the pressure, compressibility factor Z and the deviation from the ideal-gas law.
Graham's Law
Compare how fast two gases diffuse or effuse. Enter the molar masses of both gases (and a known rate if you have one) to get the rate ratio or the unknown rate from Graham's law.
Bonding 10
Chemical Bond Polarity
Select two elements to compare their electronegativities. The calculator shows the difference and classifies the bond as non-polar covalent, polar covalent, or ionic.
BET Surface Area
Calculate the BET specific surface area (m²/g) of a powder or porous material from the monolayer capacity, molecular cross-sectional area, and sample mass. Works with mol, mmol, or cm³ (STP) input.
Capillary Rise
Calculate how far a liquid rises (or is depressed) in a capillary tube using Jurin's law. Enter surface tension, liquid density, tube radius, contact angle and gravity to get the capillary rise in mm, cm, m or inches.
Formal Charge
Calculate the formal charge of any atom in a Lewis structure. Enter the atom's valence electrons, nonbonding (lone pair) electrons, and bonding electrons to get the charge instantly.
Bond Order
Calculate the bond order of a molecule from the number of bonding and antibonding electrons in its molecular orbitals. Enter Nb and Na to get the bond order plus its meaning for bond strength and stability.
Dipole Moment
Calculate the dipole moment of a charge separation: enter the charge magnitude and the distance between the charges, and get the result in debye and C·m, compared with real molecules.
Bond Energy Reaction Enthalpy
Estimate the enthalpy change (ΔH) of a chemical reaction from average bond energies. Enter the bonds broken and bonds formed as "energy × count", and see whether the reaction is exothermic or endothermic.
VSEPR Molecular Geometry
Enter the number of bonded atoms and lone pairs on the central atom to get the AXE notation, electron-domain geometry, molecular shape and approximate bond angles using VSEPR theory.
Degree of Unsaturation
Enter the counts of carbon, hydrogen, nitrogen and halogen atoms from a molecular formula to find the degree of unsaturation (DBE/IHD) — the total number of rings and π bonds the molecule must contain.
Bragg's Law
Bragg's Law calculator solves nλ = 2d·sin θ for lattice-plane spacing, diffraction angle 2θ, or X-ray wavelength. Enter any three of the four quantities and get the fourth instantly.
Biochemistry 9
Crude Protein
Calculate crude protein percentage from Kjeldahl back-titration data. Enter the blank and sample NaOH titre values, NaOH normality, and sample weight.
Enzyme Turnover Number
Calculate the enzyme turnover number (kcat) from Vmax and the total active enzyme concentration [E]t. Enter your rate in any common unit and get kcat in s⁻¹, min⁻¹ or h⁻¹.
Michaelis–Menten
Calculate the initial reaction velocity of an enzyme-catalyzed reaction using the Michaelis–Menten equation. Enter substrate concentration, Km, and Vmax to get v0 and the fraction of Vmax.
Crude Fibre
Calculate crude fibre as a percentage of dry sample weight. Enter the crucible and residue weights before and after ashing, plus the original dry sample weight.
Isoelectric Point
Enter the pKa values of a molecule's acidic and basic groups to find its isoelectric point (pI) — the pH at which the net charge is zero. Based on Henderson-Hasselbalch charge fractions, with a per-group charge breakdown.
Biochemical Oxygen Demand
Calculate the 5-day biochemical oxygen demand (BOD₅) of a diluted water sample from initial and final dissolved oxygen, dilution fraction, and optional seed correction, following APHA Standard Methods 5210B.
Osmotic Pressure
Calculate the osmotic pressure of a solution from its molarity, temperature and the van 't Hoff factor using the van 't Hoff equation π = iMRT. Results are shown in atm, kPa, mmHg and psi.
DNA Melting Temperature
Estimate the melting temperature (Tm) of a DNA oligonucleotide from its sequence and salt concentration. Enter one strand (A, C, G, T) and the Na⁺ concentration to get the Tm and GC content.
Partition Coefficient
Enter the equilibrium concentrations of a solute in the organic and aqueous phases to get the partition coefficient P, log P, and the percentage of solute in each layer.
Spectrophotometry 6
Photon Energy
Calculate the energy of a photon from its wavelength or frequency. Enter either value and get the energy per photon in joules and electronvolts, plus the energy per mole of photons in kJ/mol.
Chromatography Retention Factor
Calculate the chromatographic retention factor k′ from the analyte retention time and the column dead time. Enter both times in any unit and get k′, the adjusted retention time, and an interpretation.
Chromatography Theoretical Plates
Calculate the number of theoretical plates (N) of a chromatographic column from a peak's retention time and width, using either the half-height (USP/Ph. Eur.) or baseline method. Optionally enter the column length to get the plate height (HETP).
Beer–Lambert Law
Enter molar absorptivity, concentration, and path length to calculate a solution’s absorbance and percent transmittance using the Beer–Lambert law.
Rydberg Equation
Enter the initial and final principal quantum numbers of a hydrogen electron transition and get the wavelength, frequency and photon energy of the spectral line, plus its series (Lyman, Balmer, Paschen…).
Chromatography Selectivity Factor
Enter the retention times of two compounds and the column dead time to compute the selectivity factor (α) and both retention factors, and see how well the column separates the pair.
Buffers 4
Acetate Buffer Composition
Enter a target pH and total buffer strength in mM to estimate the acetic acid and sodium acetate trihydrate needed for an acetate buffer. Results are given as % w/v.
Henderson–Hasselbalch
Calculate the pH of an acid–base buffer from the pKa and the amounts of acid and conjugate base, or find the base-to-acid ratio needed to hit a target pH. Enter pKa and concentrations to get the result instantly.
Ionic Strength
Calculate the ionic strength of a solution from the molar concentration and charge of each dissolved ion. Enter up to six ion species and get I in mol/L, plus each ion's contribution.
Buffer Capacity
Calculate buffer capacity (β) from the concentrations of a weak acid and its conjugate base, the pKa, and the pH. Enter the acid and base concentrations, pKa, and target pH to get β in mol/L per pH unit, the effective buffering range, and a strength assessment.
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