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