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Molar concentration is the amount of solute in moles per cubic decimetre of solution. Square brackets can denote molar concentration.

$n = VC therefore C = n/V$

Use V in dm³ when calculating C in mol dm⁻³. Rearrange the same relationship to find amount or volume, and keep the solution volume distinct from the solute mass.

Convert volume before substitution: 500 cm³ = 0.500 dm³, so 0.250 mol in that solution gives C = 0.500 mol dm⁻³. The denominator is the final solution volume, not the volume or mass of solute alone.

$For dilution with no solute loss or reaction: n_before = n_after, so c₁V₁ = c₂V₂$

Adding solvent increases the final solution volume while the amount of solute stays constant, so concentration decreases. Use the final solution volume—not the solvent volume added—and do not apply c₁V₁ = c₂V₂ when solute reacts or is removed.

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Calculate the molar concentration of the resulting solution of lithium hydroxide.

Retrieve the quantitative chain: count entities with mN_A, sum relative masses from formulae, convert mass with n=m/M, derive formula ratios, use n=VC for solutions, and apply gas-volume ratios at the same temperature and pressure.

Before finalising, check the requested entity, formula subscripts, units, dm³ conversion, balanced-equation coefficients, and any limiting reactant.

1.4.5—Molar concentration

Molar Concentration

The Mole Summary

Calculating Concentration