Molarity
Molar concentration c = n/V: mass needed to prepare a solution, mass percent to molarity, dilution, with a solution.
What to find:
Molar concentration (molarity) is the number of moles of solute in 1 liter of solution (also written M: 0.1 M = 0.1 mol/L). Write formulas in Latin letters starting with a capital: H2SO4, Ca(OH)2, CuSO4·5H2O (water of crystallization after a dot or *).
The molarity calculator finds the concentration of a solution from the amount or mass of solute, the mass needed to prepare a solution, converts mass percent to molarity and back, and solves dilution problems.
Formulas
c = n/V = m/M · V (mol/L)
V is the volume of solution in liters. A solution with 0.1 mol/L is often written as 0.1 M.
| Problem | Formula |
|---|---|
| mass of solute for a solution | m = c · V · M |
| from mass percent (w in %, ρ in g/mL) | c = 10 · ρ · w / M |
| dilution | c1 · V1 = c2 · V2 |
Example. 250 mL of 0.1 M NaOH needs m = 0.1 · 0.25 · 40 = 1 g of sodium hydroxide.
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