Molarity Question

Here's my attempt...

Thank you for the reply, I've been thinking about this problem for the past few days and I think it's saying that you have this given solution (1mM), but given the limitation that you can only take out 1 micro liter, what concentration does it need to be in order to end up with a 5nM solution with a volume of 1 mL. This means that v1 is set to your limitation (1 microliter) since you have to remove that amount and dilute it to 1mL. This means c1 is unknown and can't be 1mM since you are trying to find out what you need to dilute the 1mM solution to in order to get a 5nM solution with a volume of 1 mL.
Since c2 and v2 are both known as they're the values you want to end up with, I believe this is the way to solve this problem:

v1c1=v2c2
(1microliter)c1=(1ml)(5nM)
(1microliter)c1=(1000microliters)(5nM)
c1= 5000nM

So, you need to dilute the 1mM stock solution to 5000nM, then take 1microliter of that and dilute to 1mL to have a solution with a concentration of 5 nM.

If you or anyone can double check me on this logic, I'd really appreciate it.

Your logic is right...but you need to be careful about your units.. Take a moment and learn about conversions and try to follow the solution suggested by bio_man.

I double checked my conversion work as I did the problem and thought I made the necessary unit conversions. What part of it is wrong?

whoops, I think I see it, that last sentence should be 5000nM, not 5nM. I wrote 5000 on my paper, but just typed it wrong. Is this what you were referring to?

Or did you mean that the answer would be easier to read as 5 microM?

The unit shouldn't matter Simon.

Unit conversion is very important when doing dilution problems..think about it if you have a concentrated solution like sulfuric acid and if you don't pay attention 5M vs 50M makes a lot of difference. Sig figs and units are very important in physical chemistry.

Excellent point

@simon Are we good with this?