Question

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?

Answer 1

The molarity of the stock solution of luminol is 1.2 M

calculation

step 1: find the moles of luminol using (moles= mass/molar mass) formula

molar mass of Luminol= 177 g/mol

moles is therefore= 16.0 g/ 177 g/mol=0.0904 moles

Step 2: find the molarity using (molarity= moles/volume in liters) formula

convert Ml into liters = 75.0/1000= 0.075 L

molarity is therefore= 0.0904 moles/ 0.075 L= 1.2M