What is the concentration when 25.0 mL of a 2.04 M methanol solution is diluted to 500.0 mL?

1. Rearrange the dilution equation to C2 = C1V1 / V2. 2. Both volumes are in millilitres, and since they appear as a ratio the units cancel without conversion. 3. Substituting gives C2 = 2.04 M x 25.0 mL / 500.0 mL. 4. The result is 0.102 M. 5. The volume grows twenty-fold, so the concentration must fall twenty-fold, which 2.04 divided by 20 confirms. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.3 Molarity_