Glossary
dilution
Dilution lowers a concentration by adding solvent: C₁V₁ = C₂V₂ because the amount of solute stays the same.
Dilution lowers a solution's concentration by adding more solvent — usually water — without adding any more solute. The solute's amount does not change, so the starting concentration times its volume equals the finishing concentration times its volume: C₁V₁ = C₂V₂. Use it either way: to find the new concentration, C₂ = C₁V₁ ÷ V₂, so 100 mL of a 10% solution brought to 250 mL becomes (10 × 100) ÷ 250 = 4%; to find how much of a stock you need, V₁ = C₂V₂ ÷ C₁. The direction is a built-in check: adding water always makes the concentration weaker, so C₂ must come out below C₁. The common error is to flip the volumes in the ratio, which lands the answer above the starting concentration — a result that is physically impossible for a dilution.
Taught in
Related terms
- percent concentration — Concentration is how much solute is in a solution: percent concentration is the solute over the whole solution, times 100.
- solute — The solute is the substance that dissolves in a solvent — usually the lesser amount, like the salt in salt water.
Source: OpenStax Chemistry 1e and Chemistry: Atoms First 1e, first editions (CC BY 4.0). Each definition restates the Chemistry guide in this exam, which carries the per-source citations on its own page. (OpenStax 1e accessed 2026-10-08)