In <1993Jan22.191802.28683@magnus.acs.ohio-state.edu> tdunsize@magnus.acs.ohio-state.edu (Todd Dunsizer) writes:
>In response to your question about a chemical reaction to give blue light.
>The oxidation of luminol gives an erie blue glow. This is a common
>demonstration given in freshman lectures. Luminol is oxidized with hydrogen
>perox unfortunately, i forgoet the chemical name and formula of this compound.
>It has been quite some time since I've seen it done.
Ok... I'll take an hour of my life and type this one up...
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Chemicals and Reagents Needed for Experiment
Parts A&B - Glacial acetic acid (2 ml); 8% hydrazine solution (2ml), prepared by
diluting 12.5 g of commercial 64% hydrazine to 100ml; 3-nitrophthalic acid (1g);sodium hydrosulfite dihydrate (3 g); 3 M sodium hydroxide (5ml); triehylene
glycol (3ml); blue litmus or pH paper.
Part C - Dimethyl sulfoxide (5ml); 3% hydrogen peroxide (30ml); luminol (0.1g)
from part B; potassium ferricyanide (1-2g); potassium hydroxide (ca. 12
pellets); 3 M solution sodium hydroxide; 3 M hydrochloric acid.
Part D - Ammonium hydroxide; concentrated (20 ml); 0.2% hydrogen peroxide (4ml);luminol (80mg); 0.01 M cuprocyanide (10ml).
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Part A - 3-Nitrophthalhydrazide.
Pour 15 ml water into a small beaker or flask and heat it on a steam bath or
with a heat lamp for use a little later in the experiment. Place 1.00 g
(0.00474 mole) of 3-nitrophthalic acid and 2 ml (0.005 mole) of an 8% (by
weight) solution of aqueous hydrazine into a large test tube (ca. 20x150 mm or
25x200 mm). Add a boiling chip, mount the tube at a slight angle on a support
rack or ting stand, and heat the mixture with a small burner flame to dissolve
the solid material. Add 3 ml of triethylene glycol and insert a thermometer
so that it rests on the bottom of the test tube. Boil the solution to remove
excess water, allow the temperature to rise rapidly (a period of several
minutes) to 215!, and maintain a temperature of 210-200! for 3-4 min. Let the
reaction mixture cool to 100!, add 15ml of the hot water prepared at the
beginning of the experiment, and cool the test tube in running water. Collect
the light yellow granular product and use it without purification or drying in
the next step.
Part B - 3-Aminophthalhydrazine (Luminol)
Rinse the test tube used in part A and place the wet 3-Nitrophthalhydrazide
from the previous experiment into it, together with 5 ml of 3 M sodium
hydroxide solution and 3.0 g (0.014 mole) of sodium hydrosulfite dihydrate
(also called sodium dithionite), Na2S2O4 * 2 H2O. Heat the mixture to boiling,
stir, and maintain boiling for 5 min. Cool the reaction mixture, and in a hood
slowly add about 2 ml of glacial acetic acid (enough to make the suspension
acidic to litmus or pH paper). Collect the precipitated luminol by suction
filtration, wash it with a littl water, and allow it to dry or dry it in an
oven (reported mp = 310!). The moist material can be used in the
chemiluminescent experiment.
Part C - Chemiluminescence.
Mix 0.1 g of luminol (or the approximate weight of moist materal which
corresponds to this) with 10 ml of 3 M sodium hydroxide in a 1-L Erlenmeyer
flask and dilute the solution to about 500 ml. Add 20 ml of ordinary 3%
hydrogen peroxide solution. Now move to a darkened area. Add about 0.5 g
of small crystalline chunks of potassium hexacyanoferrate(III) (also known
as potassium ferricyanide) to the solution, swirl it, and note what happens.
Pour some of the luminescent solution into a small beaker and immediately add
some 3 M sodium hydroxide into another small beaker and add some of the
luminescent solution. Note what happens in the vicinity of the sodium
hydroxide.
When the light from the flask begins to fade, add a few more chunks of potassiumhexacyanoferrate(III). The next time the light fades, try adding a little 3 M
sodium hydroxide.
Part D - Chemiluminescent Clock
Transfer about 40 mg of the luminol product to a 125-ml Erlenmeyer flask and
dissolve it in 10 ml of concentrated ammonium hydroxide. Add 5 ml of a 0.01 M
aqueous solution of potassium tricyanocuprate(I), K2Cu(CN)3, (also known as
potassium cuprocyanide). Measure out 4 ml of 1.5% hydrogen peroxide solution
and bring it, together with the luminol solution, to a darkened room. Add the
hydrogen peroxide solution to the luminol, note the time (nearest 2-3 sec), and
swirl the flask gently in the dark until the delayed "clock reaction" is
observed. Note the time. Repeat the experiment with 3% hydrogen peroxide
solution and observe the results. For an interesting discussion of this
reaction, see E. H. White, J. Chem. Educ., 34, 275 (1957).
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Taken w/o permission from "Theory and Practice in the Organic Laboratory"
John A. Landgrebe, University of Kansas
Third Edition
Copyright (hehe) 1982 D.C. Heath and Company
(pp. 456-459)
--
The movement of the Tao consists in Returning. =-=-=-=-=-=-=-=-=-=-=-=-=-
The use of the Tao consists in softness. -mtymp15@staff.tc.umn.edu-
All things under heaven are born of the corporeal; =-=-=-=-=-=-=-=-=-=-=-=-=-
