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.
Mass percent to ppm converter
0.1% by mass is 1000 ppm, or 1,000,000 ppb. Turn the weight percent on a bottle or certificate into the ppm and ppb that environmental, drinking-water and food…
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Mass to gas volume calculator
32 g of oxygen at 1 atm and 273.15 K fill about 22.4 L, one mole of gas. Enter a gas mass, its molar mass, the pressure and the temperature in kelvin to get the…
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Mass-to-mass stoichiometry calculator
4 g of hydrogen give 36 g of water. Enter the reactant mass, both molar masses and the two coefficients from your balanced equation, and get the theoretical…
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mg/L to molarity calculator
5844 mg/L of sodium chloride, at 58.44 g/mol, is 0.1 mol/L. Turn the milligrams per litre on a water-quality sheet or lab assay into the molarity that…
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Molar concentration calculator
Half a mole of solute in 2 L of solution is 0.25 mol/L. Enter moles and volume, or a weighed mass with its molar mass, and get the molarity of the solution you…
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Molar mass from boiling point elevation
With a Kb of 0.512, a rise of 0.256 K from 5 g of solute in 0.1 kg of solvent points to 100 g/mol.
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Molar mass from gas density calculator
A gas with a density of 1.429 g/L at 1 atm and 273.15 K has a molar mass of about 32 g/mol. Enter density, pressure and temperature in kelvin to identify an…
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Molarity from moles and volume calculator
One mole dissolved to 1 L is 1 M, and half a mole made up to 2 L is 0.25 mol/L. When the moles are already known, divide by the final volume in litres for a…
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Molarity to molality calculator
1 M sodium chloride with a density of 1.04 g/mL is about 1.019 mol/kg. Turn a stock solution's molarity into the molality that freezing-point and boiling-point…
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Mole fraction to mass percent calculator
A solute mole fraction of 0.5 with molar masses of 32 and 18 g/mol means 64% of the mass is solute.
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Osmolarity calculator
0.1 mol/L sodium chloride splits into 2 particles and gives 0.2 Osm/L, twice what glucose at the same molarity gives.
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Oxygen for combustion calculator
One mole of propane, C3H8, needs 5 moles of oxygen to burn completely and gives 3 moles of carbon dioxide and 4 of water.
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Particles to moles calculator
6.02214076 × 10²³ particles are exactly 1 mole: type how many atoms, molecules or ions you have and get the amount in moles, divided by the fixed Avogadro…
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Percent composition calculator
Water is about 11 % hydrogen and 89 % oxygen by mass: type a formula and see each element's share of the molar mass, with the atoms counted, the atomic weight…
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Percent to molarity calculator
37 % hydrochloric acid with a density of 1.19 g/mL and a molar mass of 36.46 g/mol is about 12 mol/L: enter the bottle's percent, density and molar mass to get…
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Percent water in hydrate calculator
A 5 g hydrate that leaves 3.2 g of dry salt after heating held 36 % water: enter the two crucible weighings and get the water lost, the percent water and the…
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Strong acid pH calculator
0.1 mol/L hydrochloric acid has a pH of 1: enter the molarity of a strong monoprotic acid such as HCl or HNO3 and get the pH as minus the logarithm of that…
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PPB concentration calculator
0.001 g of solute in 1000 g of solution is 1000 ppb: enter the solute mass and the total mass in the same unit and get the parts per billion and the mass…
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PPM from molarity calculator
0.001 mol/L of sodium chloride (58.44 g/mol) at a density of 1 g/mL is 58.44 ppm by mass. Enter molarity, molar mass and density, and see the solute and…
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Equilibrium direction predictor
With Q at 0.25 and K at 4, Q is below K, so the reaction shifts forward toward products. Enter the reaction quotient and the equilibrium constant to see the…
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Rate constant from half-life calculator
A first-order half-life of 10 seconds gives a rate constant of 0.0693147181 per second, because k is ln 2 divided by the half-life.
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Graham's law calculator
Hydrogen at 2.016 g/mol effuses 3.9840953644 times as fast as oxygen at 32 g/mol, about four times, because the effusion rate falls with the square root of…
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Reaction order from rate data calculator
If doubling the concentration from 0.1 to 0.2 raises the initial rate from 0.01 to 0.04, the reaction is second order in that reactant.
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Solution boiling point calculator
Water that boils at 100 °C, with Kb of 0.512 and a 0.5 mol/kg solute, boils at 100.256 °C as a solution.
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Specific heat from calorimetry calculator
A 100 g sample that absorbs 4184 J while warming by 10 degrees has a specific heat of 4.184 J/g per degree, a water-like value.
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Stock solution volume calculator
To make 100 mL of a 1 M solution from a 10 M stock, take 10 mL of stock and add 90 mL of diluent. Enter the stock concentration, the target and the final volume…
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Theoretical moles of product calculator
When one mole of nitrogen limits the ammonia synthesis, at most two moles of ammonia can form. Enter the limiting moles and both balanced coefficients to get…
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Theoretical yield from limiting reactant calculator
Two moles of hydrogen limiting the water synthesis give at most 36 g of water. Enter the limiting moles, both coefficients and the product's molar mass to get…
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Total ion concentration calculator
A 0.10 mol/L sodium chloride solution holds 0.20 mol/L of ions, because each formula unit splits into two.
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Total pressure of gas mixture calculator
The partial pressures of oxygen, nitrogen and argon in dry air add up to a total of 1 atm: that is Dalton's law.
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Van der Waals pressure calculator
One mole in 22.4 L at 273.15 K, with a of 3.592 and b of 0.04267, comes out just under 1 atm once attraction and molecular size are counted.
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Vapor pressure molar mass calculator
A relative vapor-pressure lowering of 0.02 with 5 mol of solvent and 10 g of solute points to a molar mass of 98 g/mol.
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Volume percent calculator
25 mL of solute in 100 mL of solution is 25 % v/v. Enter both volumes in the same unit and get the percent by volume plus the volume fraction, ready for a…
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Volume-to-volume gas stoichiometry calculator
With 2 H₂ + O₂, 4 litres of hydrogen react with 2 litres of oxygen. Enter the known gas volume and the two coefficients from the balanced equation; at the same…
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Work of gas expansion calculator
A gas expanding by 2 L against a constant 1.5 atm does −3 L·atm of work under the chemistry sign convention.
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Zero-order half-life calculator
With k of 0.05 and a starting concentration of 1, the zero-order half-life is 10 time units. Enter the rate constant and the initial concentration to see how…
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Double slit calculator
Get the gap between bright fringes in Young’s experiment: slits 0.5 mm apart, 600 nm light and a screen 2 m away give fringes 2.4 mm apart.
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Focal length calculator
Measure where the object and its image sit and get the focal length: an object at 30 with its image at 15 means a focal length of 10, a converging lens.
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Refractive index calculator
Light moving at two-thirds of its vacuum speed gives a refractive index of 1.5. Enter either the medium speed or the index and get the other, with c set to…
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Thin lens calculator
An object 30 units from a lens with a focal length of 10 forms a real, inverted image 15 units away at half size.
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Sound level distance calculator
A source measured at 90 dB from 1 metre is about 83.98 dB from 2 metres. Enter the level you measured, the distance where you measured it and a new distance to…
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Frequency calculator
Sound travelling at 340 metres per second with a wavelength of 0.68 metres has a frequency of 500 hertz.
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String harmonic frequency calculator
A 1 m string under 100 N of tension with a linear density of 0.01 kg/m vibrates at 50 Hz in its lowest mode.
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Factor of safety calculator
An ultimate strength of 400 MPa against a working stress of 100 MPa gives a factor of safety of 4: the capacity holds the working stress four times over.
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Poisson's ratio calculator
A lateral strain of −0.003 with an axial strain of 0.01 gives a Poisson’s ratio of 0.3, typical of many metals.
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Engineering strain calculator
A 2 mm stretch on a 100 mm gauge length is an engineering strain of 0.02, or 2 %. A negative change means compression; both lengths just need the same unit.
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Boiling point altitude calculator
At sea level pure water boils at 100 °C (373.15 K, 212 °F), and thinner air at altitude lowers that point.
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Combined gas law calculator
Halve the volume from 2 to 1 while pressure doubles from 1 to 2, and the temperature stays at 300 K: P·V/T is the same in both states.
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Coefficient of performance calculator
A fridge that removes 400 units of heat for 100 units of work has a COP of 4; as a heat pump the same pair delivers 500 and scores 5.
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Volumetric flow rate calculator
A pipe with a 0.01 m² cross-section and fluid moving at 1.5 m/s carries 0.015 m³/s. Enter the area and the mean speed and get the discharge in matching units…
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Carnot efficiency calculator
An engine working between 600 K and 300 K can reach at most 50 % efficiency. Enter the hot and cold reservoir temperatures in kelvin to get the Carnot limit as…
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Latent heat calculator
Melting 0.5 kg of ice with a latent heat of 334000 J/kg takes 167000 J. Enter the mass that changes phase and its latent heat of fusion or vaporization, and the…
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Poiseuille flow calculator
A 1 m tube of radius 0.01 m, carrying a fluid of viscosity 0.001 Pa·s under a 1000 Pa pressure difference, passes 0.0039269908 m³/s.
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Stefan-Boltzmann calculator
A perfect black body of 1 m² at 300 K radiates 459.300327939 W. Enter the surface area, the emissivity and the absolute temperature to get the radiated power…
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Volumetric expansion calculator
One litre of ethanol, with β of 0.000207 per kelvin, heated by 50 K grows by 0.01035 L to 1.01035 L.
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Angular size calculator
The Sun, 1392000 km across and 149597870.7 km away, spans about half a degree on the sky. Enter any size and distance in the same unit and get the exact angle…
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Apoapsis and periapsis calculator
An orbit with a semi-major axis of 7000 km and an eccentricity of 0.05 swings out to 7350 km and in to 6650 km.
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Apparent brightness calculator
Double the distance to a star and its apparent brightness falls to a quarter; triple it and it drops to a ninth.
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Planet escape velocity calculator
Leaving Earth, with 5.972e24 kg of mass and a 6371000 m radius, takes just over 11 km/s in the ideal case.
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Distance modulus calculator
A star of apparent magnitude 10 and absolute magnitude 5 has a distance modulus of 5 and lies 100 parsecs away, or 326.1563777167 light-years.
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