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 H20.
What is the molarity of the stock solution of luminol?
To calculate the molarity of the stock solution, we first need to determine the number of moles of luminol in the solution.
Step 1: Calculate the molar mass of luminol (C8H7N3O2):
C = 12.01 g/mol
H = 1.01 g/mol
N = 14.01 g/mol
O = 16.00 g/mol
Molar mass of luminol = (8 x 12.01) + (7 x 1.01) + (3 x 14.01) + (2 x 16) = 249.21 g/mol
Step 2: Calculate the number of moles of luminol in 14.0 g:
Number of moles = mass / molar mass
Number of moles = 14.0 g / 249.21 g/mol = 0.056 mol
Step 3: Calculate the volume of the solution in liters:
Volume of solution = 75.0 mL = 75.0 / 1000 = 0.075 L
Step 4: Calculate the molarity of the stock solution:
Molarity = number of moles / volume of solution
Molarity = 0.056 mol / 0.075 L = 0.747 M
Therefore, the molarity of the stock solution of luminol is 0.747 M.