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

Question

Part A The forensic technician at a crime scene has just prepared a luminol stock solution by adding 16.0 g of luminol into a total volume of 75.0 mL of H2O. What is the molarity of the stock solution of luminol? Express your answer with the appropriate units. View Available Hint(s) molarity of luminol solution1.21 M Previous Answers Correct Part B Before investigating the scene, the technician must dilute the luminol solution to a concentration of 6.00x10 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? Express your answer with the appropriate units. View Available Hint(s) moles of luminol0.120 mol Previous Answers

Explanation / Answer

A)

luminol molar mass = 177.16 g/mol

mass, m = 16.0 g

use:

number of mol,

n = mass/molar mass

=(16.0 g)/(1.772*10^2 g/mol)

= 9.031*10^-2 mol

volume , V = 75 mL

= 7.5*10^-2 L

use:

Molarity,

M = number of mol / volume in L

= 9.031*10^-2/7.5*10^-2

= 1.21 M

Answer: 1.21 M

B)

Number of moles = M*V

= 6.00*10^-2 M * 2.00 L

= 0.120 mol

Answer: 0.120 mol

C)

number of mol = 0.120 mol

M = 1.21 M

V = ?

use:

V = number of mol/M

= 0.120 mol / 1.21 M

= 0.0992 L

= 99.2 mL

Answer: 99.2 mL

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