Question

Help on part "c":

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 19.0g of luminol into a total volume of 75.0mL of H2O.

a)What is the molarity of the stock solution of luminol?
anwer I got: molarity of luminol solution = 1.43M

b)Before investigating the scene, the technician must dilute the luminol solution to a concentration of 6.00×10−2 M. The diluted solution is then placed in a spray bottle for application on the desired surfaces.

I cannot get the correct answer for "c"...I have tried: 172mL,11.9mL, and 1.19*10^4. The only other possibility that I can come up with is: 83.9mL. Would this one be correct?...Or...am I still completely out to lunch???

c)How many moles of luminol are present in 2.00 L of the diluted spray?
anwer I got: moles of luminol =
0.120mol
What volume of the stock solution (Part A) would contain the number of moles present in the diluted solution (Part B)?
Express your answer in milliliters.

Answer 1

I didn't check a), I assumed you have.
Diluting 1.43 to .06 M is a ratio of 23.8 to 1. So add 22.8 parts water, one part the original solution. How many moles in 2L? 2L*.06M= .120moles

What volume in stock solution has .120moles? volume=moles/conc=.120/1.43M = 83.9ml

Answer 2

this answer, 83.9mL worked...thank you for the guidance.

Answer 3

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 14.0 g of luminol into a total volume of 75.0 mL of .

What is the molarity of the stock solution of luminol?

Answer 4

14.0g of luminol total volume 75 ml
is 1.05 molarity

Answer 5

You carefully weigh out 20.00 of powder and add it to 81.00 of solution. You notice bubbles as a reaction takes place. You then weigh the resulting solution and find that it has a mass of 92.80 . The relevant equation is


Assuming no other reactions take place, what mass of was produced in this reaction?

Answer 6

A) .12 Mol
B) 79.7 ml

Answer 7

106mL

Answer 8

this is the year I am born HAHA