presumptive luminol test

Question

 

What role does the hydrogen peroxide play in the reaction?

A: Is it the the oxidizing agent and blood in the catalyst?

 

How would you describe to jury about the scientific basis for this test.

Answer 1

Yes, you are correct.  H2O2 (hydrogen peroxide) is the oxidizing agent and the iron (Fe) of hemoglobin in the blood is the catalyst.  

 

How to describe this to a jury of laymen is a little more difficult.  Of course, using slides would facilitate this, but one would want to explain what chemiluminescence is and explain that different compounds can be excited to produce a luminescent color.  Luminol is such a compound that when oxidized with H2O2 in the presence of a catalyst such as iron (there are others as well), produces a new compound that is in an "excited" state.  Blue light is emitted as a form of energy as the electrons in the molecule return to their original unexcited ground state.