The forensic technician at a crime scene has just prepared a luminol stock solution by adding 15.0g of luminol into a total volume of 75.0 \rm mL of \rm H_2O.

What is the molarity of the stock solution of luminol? 1.13M

Before investigating the scene, the technician must dilute the luminol solution to a concentration of 6.00×10−2\it 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? 0.120 moles

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

I gave you the formulas.

First determine moles which = grams/molar mass.
Then molarity = M = mols/L soln.

The last part is
M = mols/L.

mols = grams/molasr mass = about 0.08 mols, then 0.08/0.075 = about 1.13. You need to do this more accurately.

mols = M x L = 0.06 x 2L = ?

M = mols/L. You know mols and M, solve for L and convert to mL.

is there a formula that i am suppose to use?

Well, let's do some math here. We know that the molarity of the stock solution is 1.13 M and the number of moles of luminol in the diluted spray is 0.120 moles.

To find the volume of the stock solution, we can use the equation:

moles = molarity x volume

So, rearranging the equation, we get:

volume = moles / molarity

Plugging in the values, we have:

volume = 0.120 moles / 1.13 M

Calculating that, we get:

volume ≈ 0.106 L

So, approximately 0.106 liters of the stock solution would contain the number of moles present in the diluted solution.

To find the volume of the stock solution that would contain the number of moles present in the diluted solution, we can use the equation relating moles, concentration, and volume.

The equation is:

Moles = Concentration × Volume

We know the following values:

Moles of luminol in the diluted solution (Part B) = 0.120 moles
Concentration of the stock solution (Part A) = 1.13 M (moles per liter)

We need to find the volume of the stock solution, so we rearrange the equation to solve for volume:

Volume = Moles / Concentration

Substituting the known values:

Volume = 0.120 moles / 1.13 M

Calculating:
Volume = 0.106 L

Therefore, the volume of the stock solution necessary to contain the number of moles present in the diluted solution is 0.106 L or 106 mL.