Solve molarity, moles, mass or solution volume, plus dilution problems.
Molarity (C) is the amount of solute in moles divided by the volume of solution in litres. It relates to mass via the molar mass: C = m / (MW × V). For dilution problems, the moles of solute are conserved: C₁V₁ = C₂V₂. You can solve for any unknown given three known quantities.
Molarity
Molarity = moles ÷ volume = mass ÷ (molar mass × volume)
Dilution
Initial concentration × Initial volume = Final concentration × Final volume
NaCl: Na = 22.990 g/mol + Cl = 35.45 g/mol = 58.44 g/mol. This is the default value in the calculator. Use the Molecular Weight Calculator for other compounds.
1 M (1 molar) means 1 mole of solute per litre of solution. For NaCl, that's 58.44 g dissolved and made up to 1 L of solution.
Use the dilution formula: V₁ = C₂V₂/C₁ = (0.1 × 0.1) / 12 = 0.00083 L = 0.83 mL. Add 0.83 mL of 12 M HCl to a flask, then make up to 100 mL with water. Always add acid to water, not water to acid.
Molarity (M) is moles per litre of solution; it changes with temperature because liquid volume changes. Molality (m) is moles per kilogram of solvent; it's temperature-independent. Molarity is more common in general chemistry; molality is preferred for colligative properties.