Chemistry & Physics

Molarity, dilution, fundamental constants — 100% local.

Concentration from a mass

Amount of substance (n)
Molar concentration
Mass concentration

Dilution — C₁V₁ = C₂V₂

Fill in 3 of the 4 fields and leave the 4th empty — it will be calculated.

CODATA values (fundamental physical constants, 2018).

Click an element to see its details.

118 elements, classified by chemical category. Standard atomic masses (IUPAC).

All calculations are performed entirely in your browser.

Molarity: from mass to concentration

Molar concentration tells you how many moles of solute are in one litre of solution. You get there in two steps: convert the weighed mass into an amount of substance, then divide by the volume.

n = m / M  ·  C = n / V

where m is the mass (g), M the molar mass (g/mol, read from the periodic table or computed for a compound), V the volume (L) and C the concentration (mol/L). Example: 58.5 g of table salt (M ≈ 58.44 g/mol) in 1 L gives 1.0 mol/L.

Dilution

Diluting a solution adds solvent without changing the amount of solute. So the product concentration × volume stays constant.

C₁ × V₁ = C₂ × V₂

Enter three of the four values and the tool computes the fourth. To prepare 500 mL of a 0.1 mol/L solution from a 1 mol/L stock, take 50 mL of stock and make up to 500 mL.

Safety: to dilute a concentrated acid, always pour the acid into the water, never the other way round — the reaction releases a lot of heat and can splash.

Reading the periodic table

Elements are ordered by increasing atomic number (number of protons). A column (group) gathers elements with similar chemical behaviour; a row (period) corresponds to an electron shell. The molar mass shown is the standard atomic weight, an average over the naturally occurring isotopes.

Frequently asked questions

Molarity, molality, normality: what's the difference?

Molarity relates moles to the volume of solution (mol/L). Molality relates them to the mass of solvent (mol/kg), which makes it temperature-independent. Normality accounts for the number of charges exchanged.

Where do the physical constants come from?

From the CODATA 2018 values, the international reference for the fundamental constants.

Are my calculations transmitted?

No. Everything is computed in the browser; no data is sent.