Dilutions confusion - please help

Feb 2015
2
0
Hi there,
I am a biology undergrad with some highschoool chem problems based on dilutions - please help!

If I have a solution of 2.5% solution does this mean 2.5g per 100ml?

Assuming yes, that gives me 0.025g per 1ml and therefore 25mg per 1ml.

The question is what volume do I need to have 1mg of solute? I thought it was 0.04ml but the teacher says 0.4 microlitres? How have I gone wrong?
 
May 2010
491
8
dilutions

I agree with your 0.04 ml but I convert that to 40 microliters