Dilutions from Stock Solutions

If you're working in a chemistry lab, it's essential to know how to calculate a dilution. Here's a review of how to prepare a dilution from a stock solution.

You use the law of conservation of mass to perform the calculation for the dilution:

M_dilutionV_dilution = M_stockV_stock

As an example, say you need to prepare 50 ml of a 1.0 M solution from a 2.0 M stock solution. Your first step is to calculate the volume of stock solution that is required.

M_dilutionV_dilution = M_stockV_stock
(1.0 M)(50 ml) = (2.0 M)(x ml)
x = [(1.0 M)(50 ml)]/2.0 M
x = 25 ml of stock solution

So to make your solution, you put 25 ml of stock solution into a 50 ml volumetric flask. Dilute with solvent to the 50 ml line.