Hi Sheerien,

You could make this into a complicated calculation but there is an easy way when the volumes and concentrations are ll in the same units.  The answer is:

((V1 x C1) + (V2 x C2)) / (V1 + V2)

Where V = volume and C = concentration.

In your case that's:

((500 x 60) + (1000 x 6)) / (1000 + 500) = 24mM

It always a good idea to do a mental approximation of the answer you expect just to make sure you get the maths right.  In this example, think about the case where you just added 1000uL of solvent to 500uL of 60mM solution.  In that case you would simply be diluting by 1:3 and would end up with a final concentration of 20mM.  You would expect your answer to be a little higher than 20mM so 24mM makes perfect sense.

Hope that helps.

Don

Hello Donald.

Thanks a lot for the easy formula. When I did it by approximate calculation, my answer was 22. But your formula makes it convenient and accurate. 

Thank you.

Hi Sheerien,

In general when your are mixing two different  concentrations together first calculate number of moles for each solution (n=CV ,V-in liter) then add them together it will be total moles,then concentration of mixture will be = total moles / total volume(liter).

Regards,