Question

A. The forensic technician at a crime scene has just prepared a luminol stock solution by adding 13.0 g of luminol into a total volume of 75.0 mL of H2O.

-What is the molarity of the stock solution of luminol?

B. Before investigating the scene, the technician must dilute the luminol solution to a concentration of 5.00×10−2 \ 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?

What volume of the stock solution (Part A) would contain the number of moles present in the diluted solution (Part B)?

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Answer 1

M = mols/L
mols = g/molar mass
Therefore, determine molar mass, divide into grams luminol and divide that by 75 mL (in liters) to obtain molarity = M.

B. M x L = mols
You know M and you know L, calculate mols.
C. Mols = M x L.
You know mols from B, you know molarity (M) from part A, calculate L.
Post your work if you get stuck.

Answer 2

thank you :)