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🔬 ScienceFree
pH after dilution calculator
See the new pH of a strong acid once you add water: pH 1 taken from 10 mL to 100 mL becomes pH 2. You also get the dilution factor, every step and whether the…
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Dilution to target ppm calculator
To make 100 mL at 50 ppm from a 1000 ppm stock, measure 5 mL of stock and add 95 mL of diluent. Enter the two concentrations and the final volume to get both…
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Dilution water to add calculator
Know exactly how much water to pour in: 100 mL of a 2 M stock needs 300 mL of water to reach 0.5 M, for 400 mL in total.
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Ebullioscopic constant calculator
Get a solvent's ebullioscopic constant from your own boiling-point data: a rise of 0.512 °C in a 1 mol/kg solution with a van 't Hoff factor of 1 gives Kb…
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Electrode potential vs pH calculator
Find the reversible potential of a hydrogen electrode from the solution's pH and the hydrogen pressure; at pH 7 and 1 bar it sits at −0.414 V.
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Electrolysis time calculator
Plan how long the current has to flow, since depositing 1 g of copper at 1.5 A takes just over half an hour.
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Electron configuration calculator
Type an atomic number and get the ground-state electron configuration: iron, Z 26, is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁶, or [Ar] 4s² 3d⁶, with 8 valence electrons.
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Electrorefining efficiency calculator
Compare the metal you actually recovered with what the charge should have deposited: 9.2 g against a theoretical 10 g is 92 % current efficiency, with 0.8 g…
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Empirical formula calculator
Type each element's amount and get the simplest whole-number formula: 40 % carbon, 6.7 % hydrogen and 53.3 % oxygen give CH2O.
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Empirical formula from masses calculator
Turn weighed element masses and the atomic masses from your worksheet into an empirical formula: 40 g of carbon, 6.7 g of hydrogen and 53.3 g of oxygen give…
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Reaction heat for amount calculator
Scale a molar reaction enthalpy to the amount that really reacts: 2 mol at −92.2 kJ/mol give a heat of −184.4 kJ, labelled exothermic because the system…
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Enthalpy scaled by coefficients calculator
Rescale the enthalpy of a thermochemical equation when you multiply its coefficients: doubling a step of −92.2 kJ gives −184.4 kJ, still exothermic.
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Heat of combustion per gram calculator
Turn a molar heat of combustion into energy per gram of fuel: methane at −890 kJ/mol and 16.04 g/mol releases about 55.5 kJ per gram.
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Enthalpy of dilution calculator
Turn a calorimetry reading into a molar enthalpy of dilution: −8.4 kJ measured while diluting 0.2 mol of solute gives −42 kJ/mol, an exothermic dilution.
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Enthalpy from heats of formation calculator
Get a reaction enthalpy straight from a formation table: burning methane, with −393.5 kJ/mol for carbon dioxide, −285.8 for water and −74.8 for methane, gives…
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Enthalpy from internal energy calculator
Turn a bomb-calorimeter ΔU into the ΔH that constant-pressure tables use: with ΔU of −1000 J, 1.5 fewer moles of gas and 298.15 K, ΔH ends up well below ΔU.
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Enthalpy of fusion calculator
Get the molar enthalpy of fusion from a melting measurement: 2 mol of ice absorbing 12.02 kJ give 6.01 kJ/mol, in line with tabulated values for water.
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Enthalpy of vaporization calculator
Get a liquid's molar enthalpy of vaporization from the heat it absorbed and the moles that turned to vapor: 40.7 kJ for 1 mol of water near 100 °C gives 40.7…
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Enthalpy of reaction calculator
Find whether a reaction releases or absorbs heat from formation enthalpies: methane burning in oxygen to carbon dioxide (−393.5 kJ/mol) and two moles of water…
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Reaction entropy change calculator
See how much a reaction changes disorder: making ammonia from N2 at 191.6, three H2 at 130.7 and two NH3 at 192.8 J/(mol·K) gives −198.1 J/(mol·K), an entropy…
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Equilibrium constant calculator
Get Kc straight from equilibrium concentrations: two reactants at 0.5 mol/L and one product at 2 mol/L, all with coefficient 1, give Kc 8.
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Equilibrium constant from cell potential
See how a cell voltage fixes an equilibrium constant: a Daniell cell at 1.1 V with 2 electrons at 298.15 K has K of about 10³⁷.
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Equilibrium partial pressure from Kp calculator
Give Kp, the starting pressure of pure A and the coefficients, and get every partial pressure at equilibrium: for A ⇌ B + C with a Kp of 0.25 and 1 atm of A…
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Equivalent weight calculator
Get the equivalent weight from molar mass and n-factor in one step: sulfuric acid at 98.079 g/mol with both protons reacting gives 49.0395 g per equivalent.
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Excess reactant remaining calculator
Find how much of the excess reactant is left over: 28 g of nitrogen and 10 g of hydrogen making ammonia use up all the nitrogen and leave 4 g of hydrogen…
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Faraday electrolysis mass calculator
Estimate how much metal plates out: 2.5 A for 3600 seconds in a copper bath, at 63.546 g/mol with two electrons per ion, deposits just under 3 g of copper.
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Final temperature of mixture calculator
Find the final temperature two bodies share: 100 g of water at 20 °C and 50 g of metal at 80 °C settle just a few degrees above 20 °C, because the water's heat…
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First-order half-life calculator
Turn a first-order rate constant into a half-life: with k of 0.1 per second, half the reactant is gone after just under 7 seconds, whatever the starting…
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Formal charge calculator
Find the formal charge of any atom in a Lewis structure from three counts: nitrogen in ammonium, with 5 valence electrons, no lone-pair electrons and 8 bonding…
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Fraction dissociated calculator
Find how much of a weak acid has ionized: an acid with a Ka of 0.000018 at 0.1 mol/L is just over 1% dissociated, solved exactly from Ostwald's law, with the…
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Freezing mixture temperature calculator
Find the temperature of an ice-salt mixture: a salt molality of 1.5 mol/kg in water, with a cryoscopic constant of 1.86, lowers the freezing point by 2.79 °C…
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Freezing point depression calculator
Work out the freezing-point drop for any solution: one mole of sodium chloride per kilogram of water, counted as two particles with a constant of 1.86, lowers…
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Gas collected over water calculator
Correct a wet-gas reading for water vapor: 750 torr total with 23.8 torr of water vapor leaves 726.2 torr of dry gas, ready for the ideal gas law.
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Gas density at STP calculator
Get a gas's density at standard conditions from its molar mass alone: dry air at 28.97 g/mol comes to about 1.3 kg/m³ at 0 °C and 1 atm, the same figure in…
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Ideal gas density calculator
Find how dense a gas is at the conditions you actually have: dry air at 101325 Pa and 298.15 K, with a molar mass of 0.02897 kg/mol, comes to about 1.2 kg/m³.
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Gas moles calculator
Count the moles of gas in a vessel: 101325 Pa in 0.022414 m³ at 273.15 K is almost exactly one mole, the classic textbook case at 0 °C and standard pressure.
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Gas pressure from moles calculator
Find the pressure inside a sealed vessel: 1 mol of gas in 0.024465 m³ at 298.15 K presses at about one atmosphere, or 101326.6719622604 Pa.
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Electrolysis gas volume calculator
Passing 96485.3321 coulombs with two electrons per molecule releases 0.5 mol of gas, or 11.2 litres at STP.
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Gas volume from moles calculator
One mole at 101325 Pa and 273.15 K takes up 0.022413969545 m³, straight from V = nRT/P. Give the moles, pressure and absolute temperature, keep the SI gas…
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Gay-Lussac final pressure calculator
A sealed sample at 1 atm heated from 300 K to 600 K reaches 2 atm, because pressure rises in step with absolute temperature.
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Gay-Lussac's law calculator
If a gas at 300 K in a rigid container goes from 1 atm to 2 atm, its temperature reaches 600 K. Enter the starting pressure, the starting temperature in kelvin…
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Spontaneity crossover temperature
Melting ice, with ΔH of 6.01 kJ/mol and ΔS of 0.022 kJ/(mol·K), crosses ΔG of zero near 273 K. Enter both changes to get that temperature in kelvin and Celsius…
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Gibbs free energy calculator
With ΔH of −100 kJ/mol, ΔS of −0.2 kJ/(mol·K) and 298.15 K, ΔG is −40.37 kJ/mol, so the reaction is spontaneous.
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Gibbs energy from equilibrium constant calculator
An equilibrium constant of 15000 at 298.15 K gives ΔG° of −23.8371685897 kJ/mol, so products are favoured.
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Non-standard Gibbs free energy calculator
A reaction with ΔG° of −30 kJ/mol and a reaction quotient of 0.1 at 298.15 K has an actual ΔG of −35.70800950243 kJ/mol.
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Reaction spontaneity calculator
A reaction with ΔH of −100 kJ/mol and ΔS of −50 J/(mol·K) at 298.15 K has ΔG of −85.0925 kJ/mol, so it is spontaneous.
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Graham's law calculator
Hydrogen at 2 g/mol effuses four times as fast as oxygen at 32 g/mol, because rates scale with one over the square root of molar mass.
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Graham effusion time calculator
If a gas of 4 g/mol takes 10 seconds to effuse, a gas of 16 g/mol takes 20 seconds under the same conditions.
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Unknown molar mass from effusion calculator
If helium at 4 g/mol effuses twice as fast as your unknown gas, the unknown has a molar mass of 16 g/mol.
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Grams to moles calculator
36.03 grams of water at 18.015 g/mol is exactly 2 moles: the amount of substance is the mass divided by the molar mass.
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Grams to particles calculator
18.015 grams of water at 18.015 g/mol is one mole, or 6.02214076 × 10²³ molecules. Enter a mass and a molar mass to get the moles and the particle count…
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Half-life calculator
Start with 100 units and a half-life of 10: after 20 time units, 25 remain and 75 have decayed. Enter the initial amount, the half-life and the elapsed time in…
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Number of half-lives calculator
20 hours with a 10-hour half-life is exactly 2 half-lives, which leaves 25 % of the start. Enter the elapsed time and the half-life in one unit to get the…
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Molar heat capacity ratio calculator
Air-like values of Cp 29.1 and Cv 20.8 J/(mol·K) give a ratio γ of 1.399038461538. Enter the two molar heat capacities in one unit to get the adiabatic index…
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Heat of neutralization calculator
A run that releases −57.3 kJ while forming 1 mole of water has a molar heat of neutralization of −57.3 kJ/mol.
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Heat of solution calculator
Dissolving 0.1 mol of solute that releases −4.2 kJ gives a molar heat of solution of −42 kJ/mol, an exothermic process.
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Heat required to raise temperature calculator
Raising 1 kg of water with a specific heat of 4184 J/(kg·K) by 1 kelvin takes 4184 joules. Enter mass, specific heat and temperature change to get the heat…
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Henderson–Hasselbalch calculator
A buffer with a pKa of 4.76 and equal amounts of conjugate base and acid, 0.1 each, has a pH of 4.76.
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Henry's law constant calculator
A dissolved gas concentration of 0.0012 mol/L under a partial pressure of 1 atm gives a Henry's law constant of 0.0012 mol/(L·atm).
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Henry's law gas solubility calculator
With a Henry constant of 0.0013 mol/(L·atm) and a partial pressure of 1 atm, the dissolved concentration is 0.0013 mol/L.
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