The chemical 5-amino-2,3-dihydro-1,4-phthalazinedione, better known as luminol,

Question

The chemical 5-amino-2,3-dihydro-1,4-phthalazinedione, better known as luminol, is used by forensic scientists in analyzing crime scenes for the presence of washed-away blood. Luminol is so sensitive that it can detect blood that has been diluted 10,000 times. A basic solution of luminol is often sprayed onto surfaces that are suspected of containing minute amounts of blood.

Luminol has a molecular weight of 177 g/mol.

The forensic technician at a crime scene has just prepared a luminol stock solution by adding 14.0g of luminol into a total volume of 75.0 mL of H2O.

What is the molarity of the stock solution of luminol?

Before investigating the scene, the technician must dilute the luminol solution to a concentration of 5.00

Explanation / Answer

Mol luminol in 14g: = 14/177 = 0.0790mol

Molarity = mol of soluite / volume solution in litres

Molarity = 0.0790/0.075 = 1.0533

Molarity of stock solution = 1.0533M

Part B:

1 litre of the dilutes solution contains 5.00*10^-2 mol luminol (given)

2 litres contains (5.00*10^-2)*2 = 0.1 mol Luminol

c) 0.1*1000/1.053 = 94.96ml

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