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.
14.0g of luminol total volume 75 ml
is 1.05 molarity
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
A) .12 Mol
B) 79.7 ml
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?
106mL
To solve part c of the question, we need to find the number of moles of luminol present in 2.00 L of the diluted spray. We can use the molarity of the diluted solution obtained in part b to calculate this. Here's how you can do it:
1. First, calculate the moles of luminol in the diluted spray by multiplying the molarity by the volume in liters: (6.00×10^-2 M) * (2.00 L) = 0.120 mol.
2. Now we know that there are 0.120 moles of luminol in the 2.00 L of the diluted spray. We need to find the volume of the stock solution that would contain the same amount of moles. To do this, we can use the equation:
moles = molarity * volume
Rearranging the equation to solve for volume, we get:
volume = moles / molarity
3. Substitute the values into the equation: volume = 0.120 mol / 1.43 M ≈ 0.0839 L.
4. However, we need to express the volume in milliliters (mL) as requested in the question. We know that 1 L is equal to 1000 mL, so we can convert the volume by multiplying by 1000:
0.0839 L * 1000 mL/L = 83.9 mL.
Therefore, the correct answer for part c is 83.9 mL.
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?