# Question #c5ab5

Aug 20, 2015

It is not a dilution, but a concentration increase by a factor of 10

#### Explanation:

If we go for the definition of dilution factor, you would find that it refers to the final volume/aliquot volume (final volume = aliquot + diluent) [DILUTIONS: Principles and Applications, David B. Fankhauser, http://biology.clc.uc.edu/fankhauser/labs/microbiology/dilutions.htm],

In this case the question would be what is the final concentration of my solution? And if it is smaller than the initial one, yes you have a dilution, but as it seems to be in reality you are increasing the concentration of your solution.

• Lets see then the starting conc. is 5g$/$20ml = 0.25g$/$ml $=$ 250mg$/$mL $=$ 0.25mg$/$$\mu$L

• when you take 3ml and then evaporating the solvent, you are ending with:
250mg/mL$\times$ 3mL $=$ 750mg of the solute.

• dissolving them in 300$\mu$l yield the following solution
750mg$/$300$\mu$L $=$ 2.5mg$/$$\mu$L

• Now your starting concentration was 0.25mg$/$$\mu$L and your actual one is 2.5mg$/$$\mu$L then your concentration was increased by a factor of 10.

-Need to be careful with units, if you want to present them back in g$/$mL, nothing else have to be done. Because you should multiply and divide by 1000, leaving the amount unaffected.
2.5mg$/$$\mu$L $=$ 2.5g$/$mL