Science & Chemistry Calculators — United Kingdom

Find the molarity of a solution from the mass of solute, its molar mass and the solution volume — with moles, g/L and millimolar alongside.

Work out how much stock solution to dilute to make a given volume at a lower concentration — C₁V₁ = C₂V₂ — with the diluent volume and dilution factor.

How many grams of a compound to weigh out to make a solution of a given molarity and volume — the reverse of the molarity calculation.

Calculate a percent concentration — weight/volume, weight/weight or volume/volume — from the amounts, or the amount needed for a target percentage.

Convert parts per million to milligrams per litre, percent, parts per billion and mg/kg — or calculate ppm from a mass in a mass or volume.

Find how much a dissolved substance raises the boiling point and lowers the freezing point of water — ΔT = i × K × m — from the molality and the van't Hoff factor.

Convert between molarity, mass concentration, percent and ppm — the four ways the same solution gets labelled.

Convert parts per million to molarity and back — the conversion behind every water-quality and trace-analysis result.

The dilution factor from the volumes, and the concentration it produces — with the notation pinned down, since 1:10 means two different things.

The concentration at every step of a serial dilution — with the total dilution reached and the volumes for each tube.

The dilution equation solved for whichever variable you need — stock volume, final volume, or either concentration.

Convert mass concentration to molar concentration and back, using the molar mass — with the mass needed to make a given volume.

Convert a percentage concentration to molarity — for weight/volume, weight/weight or volume/volume, including concentrated acids.

How much bleach to add for a target chlorine concentration — for sanitising, disinfecting or water treatment.

The amounts for a two-part mix at a given ratio — resin and hardener, fuel and oil, concentrate and water.

Molality from mass or moles of solute and the solvent mass — the concentration unit that does not change with temperature.

The mole fraction of each component in a two-part mixture — from masses or moles, with the mass fraction alongside.

The freezing point of a solution — the depression a dissolved solute causes, and how much you need for a target temperature.

The osmotic pressure of a solution — the pressure needed to stop water flowing across a membrane into it.

Normality from molarity and equivalents — the concentration unit titrations still use, and how it relates to molarity.

Solubility product from molar solubility and back — for any salt stoichiometry, with the common-ion effect.

The ionic strength of a solution from the concentration and charge of each ion — the quantity activity coefficients and Debye lengths depend on.

Total dissolved solids in water from an electrical-conductivity reading — with the conversion factor for the kind of water, temperature compensation to 25 °C, and what the result means for drinking, irrigation or an aquarium.

Type a chemical formula — H2O, NaCl, C6H12O6, Ca(OH)2, CuSO4·5H2O — and get its molar mass with the element breakdown.

Convert between moles and grams of a substance using its molar mass — either direction.

Convert a number of atoms, molecules or ions to moles and back using the Avogadro constant, 6.022 × 10²³ per mole.

Calculate the percent yield of a reaction from the actual mass obtained and the theoretical maximum, with the loss.

Calculate the concentration of an acid (or base) from a titration — titrant volume and molarity, sample volume and the mole ratio of the neutralisation.

The molar ratio between two reactants, which one runs out first, and how much product the reaction can make.

Air-fuel ratio, lambda and equivalence ratio for any fuel — with the stoichiometric point and whether the mixture is rich or lean.

The oxygen and air a hydrocarbon needs to burn, and the carbon dioxide and water it produces — from the formula CₓHᵧ.

The mass percentage of each element in a compound — from its formula, with the mass of each element in a given sample.

The empirical formula from percent composition — and the molecular formula if you know the molar mass.

Atom economy — the share of reactant mass that ends up in the desired product — and how it differs from percent yield.

The average atomic mass of an element from the masses and natural abundances of up to four isotopes — the number printed on the periodic table.

The degree of unsaturation — how many rings and double bonds a molecular formula must contain — from its atom counts.

Convert between pH, pOH, hydrogen-ion and hydroxide-ion concentration — enter any one and get the other three.

Calculate the pH of a buffer from the pK_a of the weak acid and the concentrations of its conjugate base and acid — the Henderson–Hasselbalch equation.

Find the new volume of a gas when its pressure and temperature change — the combined gas law, which contains Boyle's, Charles's and Gay-Lussac's laws.

The reaction quotient Q from current concentrations, compared against K to tell you which direction the reaction will run.

Hydrogen ion concentration from pH, and pH from concentration — with pOH, hydroxide concentration and how far it sits from neutral.

The molar mass of a gas from its mass, volume, pressure and temperature — the ideal gas law rearranged.

The vapour pressure of a solution from the mole fraction of solvent — and the lowering a dissolved solute causes.

The partial pressure of a gas in a mixture — from its mole fraction and the total pressure, or from moles, volume and temperature.

How a liquid's vapour pressure changes with temperature — the Clausius-Clapeyron equation, and the boiling point at any pressure.

How much gas dissolves in a liquid at a given partial pressure — Henry's law, behind carbonation, diving and dissolved oxygen.

The equilibrium constant from equilibrium concentrations — with the Kc to Kp conversion and the free energy it implies.

The volume an amount of gas occupies at standard conditions — from moles or from a mass and molar mass — with the molar volume for the standard you choose.

The isoelectric point of an amino acid — the pH at which it carries no net charge — from its pKa values, for the twenty standard amino acids or any pKa set you enter.

How much of a radioactive isotope, drug or first-order reactant remains after a time, from its half-life — with the decay constant and the number of half-lives elapsed.

Estimate the age of a sample from the percentage of carbon-14 remaining, using the 5,730-year half-life — and the reverse, the fraction left after a given age.

Find the heat absorbed by the water in a calorimeter — q = m c ΔT — and the enthalpy change per mole of the reactant, from a temperature rise.

Find a solution's concentration from its absorbance, the molar absorptivity and the path length — A = εlc — or the absorbance a concentration will give.

The relative rates at which two gases effuse or diffuse — lighter gases move faster, by the square root of the mass ratio.

The rate constant for a zero, first or second order reaction — from concentrations and time, or from the half-life.

Activation energy from two rate constants at two temperatures — or the rate change a temperature shift will cause.

Gibbs free energy from enthalpy and entropy — whether a reaction is spontaneous, and the temperature at which that changes.

The lattice energy of an ionic compound — the energy holding the crystal together — by the Born-Landé equation.

The cell potential away from standard conditions — the Nernst equation, for electrochemistry, pH electrodes and membrane potentials.

The mass deposited or gas evolved in electrolysis — from current, time and the number of electrons per ion.

The enthalpy change of a reaction from the standard formation enthalpies of its products and reactants.

The approximate enthalpy of a reaction from the bonds broken and formed — the estimate you can make without a data table of formation enthalpies.

The entropy change of a reaction, a temperature change or a phase transition — the disorder term in every spontaneity calculation.

The rate constant of a reaction at a given temperature from its activation energy and pre-exponential factor — and how much faster it goes at a second temperature.

The energy released by burning a given mass of a fuel — in kilojoules, megajoules and kilowatt-hours — from its heat of combustion, with the energy per gram and the carbon dioxide produced.

The diffusion coefficient of a molecule or particle in a liquid from its size, the temperature and the viscosity — the Stokes–Einstein equation — with how long it takes to diffuse a micrometre or a millimetre.

Cross two parents for a single gene and get the genotype and phenotype ratios of the offspring — a Punnett square worked out.

Work out how many cells a culture reaches after a given time from its doubling time — exponential growth — and how many generations that is.

From the share of a population showing a recessive trait, estimate the recessive and dominant allele frequencies and the carrier (heterozygote) frequency — p² + 2pq + q² = 1.

How long light takes to travel a distance — kilometres, astronomical units or light-years — from the Moon to the nearest star.

See what you would weigh on the Moon, Mars, Jupiter and the other bodies of the Solar System — mass stays the same, gravity does not.

Round any number to a chosen number of significant figures, count the significant figures it already has, and see it in scientific notation.

Convert an absolute uncertainty on a measurement to a percentage and back, and combine the uncertainties of two measurements that are multiplied or divided.

How long water stays in a tank — hydraulic retention time — from the tank volume and the flow through it.

Water hardness converted between every scale — ppm as CaCO₃, grains per gallon, German, French and English degrees.

The temperature water boils at for a given elevation — lower air pressure, lower boiling point, longer cooking.

A linear calibration curve from your standards — slope, intercept and R² — and the concentration of an unknown from its reading.

The limit of detection and limit of quantification of an analytical method from the scatter of blank readings and the slope of the calibration curve.

The mean of repeated measurements with its standard uncertainty and the expanded uncertainty at a chosen coverage factor — the ± you report.

How much diluent to add to a vial of powder to reach a target concentration, and the volume that then contains a required amount — for lab reagents, peptides and lyophilised standards.