__Dilution Formula : C1V1 = C2V2 __

This equation applies to all dilution problems.
C1 (initial conc) x V1 (initial volume) = C2 (final conc) x V2 (final volume)

Example : What volume of 6.00 ppm solution must be used to give 4.00 liters of a 0.100 ppm solution?

C1 = 6.00 ppm

V1 = unknown

C2 = 0.100 ppm

V2 = 4 liters = 4000 mls

V1 = (C2 x V2) / C1

= (0.100 X 4000) / 6.00

= 400 / 6.00 = 66.7 mls.

This means that 66.7 mls of the 6.00ppm solution diluted to a final volume of 4 liters will give a concentration of 0.100 ppm.

The Formula below can be used to calculate the V1 component only.

req is the value you want.

req ppm x req vol

-------------------------- = no of mls for req vol

stock

e.g. Make up 50 mls vol of 25 ppm from 100 ppm

25 x 50 / 100 = 12.5 mls. i.e. 12.5 mls of 100 ppm in 50 ml volume will give a 25 ppm solution

__Serial dilutions __

Making up 10^{-1} M to 10^{-5} M solutions from a 1M stock solution.

Pipette 10 ml of the 1M stock into a 100 ml volumetric flask and make up to the mark to give a 10^{-1} M soln.

Now, pipette 10 ml of this 10^{-1} M soln. into another 100 ml flask and make up to the mark to give a 10^{-2} M soln.

Pipette again, 10 ml of this 10^{-2} M soln. into yet another 100 ml flask and make up to mark to give a 10^{-3} M soln.

Pipette a 10 ml of this 10^{-3} M soln. into another 100 ml flask and make up to mark to give a 10^{-4} M soln.