Performing a Dilution Calculation

Performing a dilution calculation means setting the stock solution's molarity times volume equal to the diluted solution's molarity times volume, then solving for whichever quantity is unknown.

A chemist needs 500 mL of 0.400 M glucose solution, prepared by diluting a 3.00 M stock solution with distilled water. Setting M1V1 equal to M2V2 gives (3.00 M)(V1) = (0.400 M)(0.500 L). Solving for V1 gives about 0.0667 L, or 66.7 mL, of stock solution, which is then measured into a flask and brought up to a total volume of 500 mL by adding water, not by adding 500 mL of water to it.