To achieve a desired final concentration using C1V1=C2V2, which quantity is typically adjusted?

• A. The volume of stock used (V1)
• B. The ambient light
• C. The pH of solution
• D. The solvent boiling point

Answer: (A)

In a dilution, the amounts of solute must balance: the product of concentration and volume stays the same before and after you dilute, which is what C1V1 = C2V2 expresses. To reach a desired final concentration, you typically adjust how much stock you add, V1. By choosing the final volume you want (V2) and knowing the stock concentration (C1) and the target concentration (C2), you solve for V1 using V1 = (C2 × V2) / C1. Then you add that volume of stock and bring the solution up to the final volume with solvent.

The other factors—ambient light, pH, or solvent boiling point—aren’t part of this dilution calculation, so they don’t determine the required amount of stock to achieve the target concentration.