Unit conversions and molarity

[205743684]

Q6. If you have DNA with a concentration of 2 µg/µl, how much DNA (in µl) must be added to make a 20 µl solution with a DNA concentration of 1 µg/µl?

I understand the basis of this question but am having a difficult time solving it as I do not know how to go about the conversions. I know that 1x10^6 micrograms are in one gram but otherwise I am stuck on figuring this out. Any help would be greatly appreciated!

Nicolena

[Chem_Mod]

You do not need to worry about converting in this example because the question is asking for the answer in ug/uL. Simply multiply 20 uL (that's the desired volume of the new solution) times the concentration of the desired solution (1 ug/uL) which should give you 20 ug of DNA. You know you have a stock solution of 2 ug/uL so divide your 20 ug of DNA by 2ug/uL to determine the amount of DNA you would need to add in terms of uL, which should give you 10 uL of the 2 ug/uL DNA solution.

[Ethan Hung 2A]

In this case, unit conversions to from μg to g or μL or L shouldn't matter -- you simply need 20μg of DNA total. At 2μg/μL, that means you would need 10μL of the original solution.