CHE201 Luminol Lab PDF

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CHE201 Luminol Lab, CHE201 Luminol Lab...

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9/3/2017

CHEMILUMINESCENCE OF LUMINOL ORG 201 LAB

Chemiluminescence • Process whereby light is produced by a chemical reaction – Reaction generates a product molecule in high energy state – Excited molecule emits a photon of light to fall back down to ground state energy

• Bioluminescence – Flashes of light emitted by the male firefly, also marine organisms (coral), jellyfish, few other fish – Luciferin and luciferase complexed with ATP

• Glow sticks – Cyalume and hydrogen peroxide

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Part 1: Preparation of 5-nitrophthalhydrazine

• Place beaker of 100 mL deionized water on hot plate in the back of the hood, boil with boiling chips • Add 0.65 g 3-nitrophthalic acid and 1.0 mL of 10% aq. hydrazine to 50 mL RBF (stockroom) • Clamp RBF, and heat with bunsen burner, agitating often • Add 2.0 mL of triethylene glycol and several boiling chips

• Heat RBF again while swirling to mix • Heat until almost all water vapor has evaporated • Should turn dark orange color • Continue to heat 2-3 minutes, but do not overheat (black tar) • Allow RBF to cool for 5 minutes, and slowly add 20 mL of hot H2O to flask • Cool to room temp, collect crystals (do not wash anything!) record yield.

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Part II: Preparation of Luminol (5-aminophthalhydrazine)

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Transfer crystals back to RBF and add 7.5 mL of 10 % NaOH (2.5 M) Add 2.0 g of sodium hydrosulfite (dithionate) Add boiling chip Boil for 5 minutes (will heat faster) Avoid overboiling by pulling flask away Cool RBF to room temp Add 1.5 mL glacial acetic acid & check pH – Let me know if not acidic

• Collect product in buchner funnel and 250 mL flask, record yield.

Part III – Chemiluminescence of Luminol • Solution A – Dissolve wet luminol crystals (and paper) into 50 mL 1% NaOH – Check to make sure basic pH

• In dark area (one at a time): – Slowly pour solutions into a 125 mL erlenmeyer with funnel

• Solution B – 50 mL (potassium ferricyanide/H2O2/H2O)

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Safety • All long hair must be tied back • Loose sleeves must be rolled back • No eating or drinking (including chewing gum!) • Everything done under the hood • Keep flammables away from bunsen burners • Hydrazine is carcinogenic (gloves at all times!) • Sodium hydrosulfite is flammable • Do not burn skin on bunsen burners

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