Science
1,125 science calculators for chemistry, physics, biology, astronomy and the Earth sciences. Each one states the relation it uses and the units it expects, so class problems, lab work and quick checks come out right, free in your browser.
Isotope abundance calculator
Work back from an element's average atomic mass to the share of each of its two isotopes: chlorine at 35.453 u with isotopes of 34.9689 and 36.9659 u is…
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Ka from pH calculator
Turn a measured pH into the acid dissociation constant: a 0.1 mol/L weak acid at pH 3 holds 0.001 mol/L of hydrogen ions, which gives a Ka of 0.00001010101 and…
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Kb from pKb calculator
Turn a pKb from your table into the base dissociation constant: a pKb of 4.75, typical of ammonia, gives a Kb of 0.000017782794 and a weak-base label, with each…
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Kc from degree of dissociation calculator
Turn a degree of dissociation into an equilibrium constant: with α of 0.1 at a starting 0.1 mol/L, Kc is 0.001111111111 mol/L, leaving 0.09 mol/L of A and 0.01…
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Kp from Kc calculator
Switch an equilibrium constant from concentrations to pressures: a Kc of 0.5 at 298.15 K with one extra mole of gas, a Δn of 1, becomes a Kp of 12.2327158495…
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Lattice energy calculator
Estimate how strongly an ionic crystal holds together: sodium chloride, with charges of 1 and 1, a Madelung constant of 1.74756, a Born exponent of 9.1 and ions…
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Product mass from limiting reactant calculator
Find how many grams of product two reactant charges can make: 10 g of oxygen and 5 g of hydrogen forming water give 11.25 g of water, because the oxygen, at…
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Mass fraction calculator
Find what share of a solution's mass is the dissolved substance: 25 g of salt in 100 g of solution is a mass fraction of 0.25, or 25 %, with 75 g of solvent…
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Mass fraction to mole fraction calculator
Turn the mass fractions of a two-part mixture into mole fractions: salt water that is 0.2 sodium chloride at 58.44 g/mol and 0.8 water at 18.015 g/mol by mass…
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Pure mass from purity calculator
Find how much of a weighed sample is the substance you actually want: 25 g of material at 98.5 % purity holds 24.625 g of pure substance and 0.375 g of…
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Mass of element in sample calculator
Find how many grams of an element a compound sample holds: 100 g of sample in which that element makes up a mass fraction of 0.32, or 32 %, contains 32 g of it…
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Mass of product from reactant calculator
Go from grams of reactant to grams of product in one step: 10 g of oxygen at 32 g/mol turning one to one into carbon dioxide at 44 g/mol gives 0.3125 mol and…
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Mass percent calculator
Get the weight-per-weight concentration printed on labels: 25 g of solute in 100 g of solution is 25 % (w/w), and a 5 % saline means 5 g of salt in every 100 g…
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Mass percent to mole fraction calculator
In a 20% sodium chloride solution, salt is only about 7 of every 100 moles. Enter the mass percent and the two molar masses to get both mole fractions, ready…
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Mass to gas volume stoichiometry calculator
10 g of a reactant at 32 g/mol with a one-to-one mole ratio release 0.3125 mol of gas, which fills 0.007645438655 m³ at 101325 Pa and 298.15 K.
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Mixing three solutions calculator
100 mL at 2 M, 200 mL at 0.5 M and 50 mL at 1 M combine into 350 mL at exactly 1 M. Enter three concentrations and volumes of one solute and see how much each…
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Mixing two solutions calculator
100 mL of a 2 M solution poured into 300 mL at 0.5 M give 400 mL at 0.875 M. Enter the concentration and volume of each solution and get the mixture's strength…
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Molality calculator
Half a mole of solute in 1 kg of water is 0.5 mol/kg, and 2 mol in half a kilogram is 4 mol/kg. Get the molality that freezing-point, boiling-point and osmotic…
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Molality calculator
0.5 mol of solute in 1 kg of solvent is 0.5 mol/kg, and every substitution step is written out next to the answer.
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Molality to molarity calculator
A 1 mol/kg salt solution with a density of 1.04 g/mL and a molar mass of 58.44 g/mol is about 0.983 mol/L.
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Molar mass calculator
Water, H2O, weighs 18.015 g/mol: two hydrogens at 1.008 and one oxygen at 15.999. Type any formula, with parentheses or a hydrate dot, and get its molar mass…
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Molar mass from freezing point depression calculator
2.5 g of an unknown in 0.05 kg of water that freezes 0.465 °C lower, with a Kf of 1.86, has a molar mass of 200 g/mol.
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Molar mass from osmotic pressure
1.2 g of solute in 0.25 L showing 0.52 atm at 298.15 K has a molar mass of 225.834754144615 g/mol.
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Molar solubility from Ksp calculator
A 1:1 salt with a Ksp of 1.8 × 10⁻¹⁰ dissolves to 0.000013416408 mol/L. Enter the Ksp and the number of cations and anions per formula unit to get the molar…
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Molar volume at STP calculator
One mole of ideal gas at 0 °C and 1 atm fills 22.414 L, so any amount in moles becomes a volume in litres and cubic metres in one step.
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Molarity to mass percent calculator
A 1 M sodium chloride solution with a density of 1.05 g/mL is 5.565714285714% salt by mass. Add the density and molar mass to turn a volumetric concentration…
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Molarity to normality calculator
0.5 M sulfuric acid used as a diprotic acid is 1 N. Multiply a molarity by the equivalents each mole supplies in your reaction and get the normality that…
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Mole fraction calculator
In a mixture of 2, 3 and 5 moles, the first component's mole fraction is 0.2. Enter the moles of every component, pick one, and get its share along with the…
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Mole fraction to molality calculator
When the solute makes up 0.1 of the moles in water, at 18.015 g/mol, the molality is 6.167699756376 mol/kg.
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Mole fraction to molarity calculator
Turn a solute mole fraction such as 0.1 into molarity, the moles per litre that titrations and stock labels use, from the solution density in g/mL and the two…
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Gas volume ratio calculator
With coefficients 2 and 1 from a balanced equation, 4 litres of the first gas match 2 litres of the second, as long as both are measured at the same temperature…
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Mole to mole conversion calculator
Four moles of hydrogen in 2 H2 + O2 → 2 H2O give four moles of water: the calculator multiplies your reactant moles by the product coefficient over the reactant…
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Molecular formula calculator
Type an empirical formula such as CH2O and a molar mass of 180.156 g/mol, and get C6H12O6 with the multiplier 6.
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Molecular formula from empirical calculator
Enter 180.156 g/mol for the compound and 30.026 g/mol for the empirical formula, and the calculator returns the multiplier 6 that turns CH2O into C6H12O6.
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Moles to grams calculator
18.015 grams of water with a molar mass of 18.015 g/mol is exactly 1 mole, and the same tool works backwards from moles to grams.
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Moles from molarity and volume calculator
2 litres of a 0.5 mol/L solution contain 1 mole of solute: the calculator multiplies molarity by volume in litres and returns the moles, with the formula shown.
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Most probable molecular speed calculator
Enter 32 g/mol for oxygen and 300 K to get the speed at which the largest share of its molecules travel, the peak of the Maxwell–Boltzmann distribution, in…
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Nernst equation calculator
A Daniell cell with a standard potential of 1.1 V, 2 electrons and a reaction quotient of 0.01 reads about 0.05916 V above standard at 25 °C.
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Neutralization moles calculator
0.025 L of acid and 0.03 L of base, both at 0.1 mol/L, neutralize 0.0025 mol and leave 0.0005 mol of base in excess.
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Normality calculator
Half an equivalent of solute in 1 litre of solution is 0.5 N, and 2 equivalents in half a litre are 4 N.
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Normality to molarity calculator
2 N sulfuric acid, with both protons reacting, is 1 M: molarity is normality divided by the equivalents each mole contributes.
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Number of atoms in sample calculator
18.015 grams of water hold 1 mole of molecules and 1.806642228 × 10²⁴ atoms, since each molecule has 3.
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Osmolarity from osmotic pressure calculator
One atmosphere of osmotic pressure at 298.15 K corresponds to about 0.0409 osmol per litre of dissolved particles.
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Osmotic pressure calculator
A 0.1 M glucose solution at 298.15 K has an osmotic pressure of about 2.45 atm, using the default gas constant of 0.08205746 L·atm/(mol·K).
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Osmotic pressure from molarity calculator
A 0.1 mol/L non-electrolyte at 298.15 K exerts about 2.446 atm when you use the litre-atmosphere gas constant; left at its default, the SI constant gives…
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Osmotic pressure difference calculator
0.3 and 0.15 osmol/L at 298.15 K give a pressure difference that pulls water toward the more concentrated side; with the litre-atmosphere constant both…
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Partial pressure at new temperature calculator
Heat a sealed flask from 298 K to 373 K and the oxygen's 0.21 atm partial pressure rises in the same ratio as the absolute temperature; doubling the kelvins…
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Partial pressure from mole fraction calculator
Air treated as 0.21 oxygen by mole at 1 atm gives an oxygen partial pressure of 0.21 atm. Enter the mole fraction and the total pressure in any unit to get each…
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Particles to grams calculator
6.02214076 × 10²³ water molecules at 18.015 g/mol weigh exactly 18.015 g, because that count is one mole.
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Parts per thousand calculator
5 g of solute in a 1000 g solution is 5 ‰: enter the solute mass and the total mass and you also get the mass fraction and the solvent mass, ready for salinity…
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Element percent by mass calculator
32 g of an element in a compound of 98 g/mol is 32.65 % by mass: enter both masses and get the percentage, the mass fraction and the substitution written out…
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Percent dissociation calculator
Starting at 0.1 and keeping 0.02 undissociated at equilibrium means 80 % has dissociated: enter the two concentrations in the same unit and get the percentage…
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Percent ionization of acid calculator
A weak acid at 0.1 mol/L with a Ka of 0.000018 is only a little over 1 % ionized: enter the concentration and Ka and the exact equilibrium is solved for you…
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Percent purity calculator
4.85 g of pure substance in a 5 g sample is 97 % pure: enter the two masses in the same unit and get the purity, the purity fraction and each step of the…
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Percent solution prep calculator
100 g of a 10 % solution needs 10 g of solute and 90 g of solvent: enter the target percent by mass and the total you want to make, and get both weigh-outs in…
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Mass percent to molarity calculator
Sodium chloride at just over five and a half percent by mass, with a density of 1.05 g/mL, is 1 mol/L: enter the mass percent, density and molar mass and get…
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Percent yield calculator
Weighing 8.5 g of dried product against a theoretical 10 g gives an 85 % yield: enter both masses and get the yield, the yield fraction and the substitution…
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pH calculator
A hydrogen ion concentration of 1 × 10⁻⁷ mol/L is pH 7, neutral: enter [H+] in moles per litre and get the pH, an acidic, neutral or basic label and each…
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pH from pOH calculator
A pOH of 4 means a pH of 10, a basic solution at 25 °C: enter the pOH and get the pH as 14 minus pOH, with an acidic, neutral or basic label and each…
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pH to pOH calculator
pH 7 at 25 °C means pOH 7 and 1 × 10⁻⁷ mol/L of both hydrogen and hydroxide ions: enter a pH from 0 to 14 and get the pOH and both ion concentrations in moles…
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