Question

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 16.0 g of luminol to H2O creating a solution with a total volume of 75.0 mL. What is the molarity of the stock solution of luminol?

Answer 1

Answer : The concentration of luminol in the solution is, 1.20 M.

Explanation : Given,

Mass of luminol = 16.0 g

Volume of solution = 75.0 mL

Molar mass of luminol = 177.16 g/mole

Molarity : It is defined as the number of moles of solute present in one liter of volume of solution.

Formula used :

$\text{Molarity}=\frac{\text{Mass of luminol}\times 1000}{\text{Molar mass of luminol}\times \text{Volume of solution (in mL)}}$

Now put all the given values in this formula, we get:

$\text{Molarity}=\frac{16.0g\times 1000}{177.16g/mole\times 75.0mL}=1.20mole/L=1.20M$

Therefore, the concentration of luminol in the solution is, 1.20 M.