Question

How can I calculate dilution concentration?

Answer 1

You use the formula `c_1V_1 = c_2V_2`.

See How do you do dilution calculations?

EXAMPLE

Describe how would prepare 50 mL of a 1.0 mol/L solution from a 2.0 mol/L stock solution.

Solution

Your first step is to calculate the volume of stock solution that is required.

`V_1` = 50 mL; `c_1` = 1.0 mol/L
`V_2` = ?; `c_2` = 2.0 mol/L

`V_2 = V_1 × c_1/c_2` = 50 mL × `(1.0"mol/L")/(2.0"mol/L")` = 25 mL

This makes sense. You want half the original concentration, so you would use half the volume of the stock solution.

So, to make your solution, you would put 25 mL of stock solution into a 50 mL volumetric flask. Then you would add solvent to the 50 mL mark.