Calculating weight needed for micromole of solution

[exodasbr]

Homework Statement

Here is the question:
What weight of neutral red (molecular weight 289) must be dissolved in 1.00 ml to give a =40.0 µM (µmol l-1) solution? Give your answer in MICROGRAMS (µg).

Homework Equations

Not sure the only one I'm aware of is mole concentration (mol dm^-3) = moles/volume but I can't seem to find the answer using this.

The Attempt at a Solution

i. I understand that moles dm^-3 = moles/volume but this is in Micrograms so I am a bit confused.[/B]

 

[Borek]

Start calculating how many grams you need, conversion from g to μg is rather trivial.