# 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

-gxelan-

Hi,
What is the molecular weight of the chemical ???

Prao

-prao-

QUOTE (prao @ Nov 29 2005, 09:03 AM)
Hi,
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

-gxelan-

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.

-pcrman-