[Calimusk07]

Hi everyone , I am having some trouble figuring out the solution to this question, which I can't seem to get my head around.

For an experiment, I have used 5 μl of Compound A ( 99 % purity) and placed it on a filter paper inside a petri dish which contains some agar to study the effect of the compound on nematodes. I want to understand just how much of this compound is present (measured in concentration) in the petri dish excluding the area containing the agar. The reason why I want to understand this is because in the future, I am planning to scale up the experiment and I would like to know the concentration of the compound necessary to achieve a similar effect on the nematodes. So to convert the volume of the Compound A into concentration, I tried doing the following calculation:-

To calculate the mass, I used mass = density x volume equation,

The relative density of Compound A = 0.657 g/mL
The volume of compound injected into the petri dish = 5 μl = 0.005 mL
Volume of petri dish without agar = 20 cm3
                                                     = 0.657 X 0.005
                                                     =  3.285 x 10^-3 g/mL / 20 cm3
                                                     = 1.6425x10^-4 g/mL

I'm just posting this to seek some guidance on what I am doing wrong ( as I'm not very good in chemistry and calculations ) and to ask your help to guide me to the right direction. If anything is unclear or if you have any questions feel free to ask !

Thanks

[chenbeier]

Beside one unit error

3.285 x 10^-3 g/mL / 20 cm3

shoud be 3.285 x 10^-3 g / 20 cm3

it sounds ok.