# calculation questions - sry ..but i am bad at such calculations..juz need to confirm (Nov/28/2005 )

hi people..i apologise for asking such a qn ..but i need to verify as i am unsure of what to do..

I have a 25mg/ml of a chemical that i need to use.how much do i need to add to a solution mix in order for me to achieve a 1uM concentration of the chemical i used in the solution mix ?

what are the working steps.i am quite stupid in this area and would thank anyone who can help me list down the various steps involve in getting my answer

Hi,

What is the molecular weight of the chemical ???

Prao

What is the molecular weight of the chemical ???

Prao

hi..the MW is 288.43 g/mol

would appreciate if you could list down e solution step by step so that i could understand better

thanks in advance

This is a dilution question because your starting material is a solution (25mg/ml).

To make a 1uM solution, use this formula

V1C1 = V2C2 (V1: volume needed, C1: original concentration, V2: desired volume, C2: desired conc.)

since your original conc. is mg/ml, you have to convet that into molar conc. To do this, think it this way, your current conc. is 25 mg/ml, that is 25g/L, or 0.087 (25/288.43) M.

Now put the numbers into the formula, assuming you want to make 100 ml of 1 uM (0.000001 M) solution.

0.087*V1 = 0.000001*100

V1 = 0.001149 ml = 1.149 ul

So, add 1.149 ul stock solution into 99.99 ml water, you will get 1 uM sol.

I find this page handy for such things...

Thank you all. I understand it already. It appears to be some basic calculations that I have done before. But anyway, you guys have been a great help .

cheers