[SoulCase]

I'm working on a worksheet right now where the stock solution is 11mM and is being diluted with distilled water among multiple test tubes. I'm pretty sure I need to use the dilution formula but am unsure what values to use for the volume. All the volumes of the test tube add up to 10mL, but have differing variations of stock solution and distilled water. The first test tube is just 10mL of stock solution with its absorbance being 1.042, and the second one has 1mL of stock solution and 9mL of distilled water and its absorbance is .102. If I wanted to find the concertation of the second test tube would this equation be correct, (11 x 10^-6)(10ml)= (M)(1ml)? If this is incorrect what values would I need to use instead?

[chenbeier]

Its only divided by 10. It would be 11×10^-7 mM
It has to be 11 x10^6-/10 ml = M/1ml

E = eps*c*d
eps, d = const.
So E ~ c.

[mjc123]

Does "11 x 10^-6" imply that the stock solution is 11 μM, not mM?

[chenbeier]

Correct.