Part A: The forensic technician at a crime scene has just prepared a luminol sto

Question

Part A: The forensic technician at a crime scene has just prepared a luminol stock solution by adding 10.0 g of luminol into a total volume of 75.0 mL of H2O.

What is the molarity of the stock solution of luminol?

Part B: Before investigating the scene, the technician must dilute the luminol solution to a concentration of 2.00×102 M . The diluted solution is then placed in a spray bottle for application on the desired surfaces.

How many moles of luminol are present in 2.00 L of the diluted spray?

Explanation / Answer

MW luminol = 177.16 g/mol

mol = mas/MW = 10/177.16 = 0.05645 mol of Luminol

M = mol/V = 0.05645 mol /V = 0.05645 / (75/1000) = 0.7526 M of luminol

B)

M = 2*10^-2 M

find n, given v = 2L

mol = M*V = (2*10^-2 M)(2L) = 0.04 mol of luminol

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