Submitted by: Thcodore A. Winkel, Shawe Science Club, Shawe Memorial High School, Madison, Indiana Checked by: Roger Wheaton, Michigan State Univrrsit,y, East Lansing PREPARATION
REMARKS
Prepare a mixt,ure of the following composition: Luminal 0.2 g. hemoglobin 4.0 g, sodium perborate 4.0 g, trisodium phosphate 30.0 g, and powdered sugar, 30.0 g. The mixture is hygroscopic, but can be kept almost indefinitely in a sealed container; since only water is necessary, it is ready for use a t any time.
The light output is not as bright as the "quick flash" produced with other oxidizing agents, but the chemicals used have some advantages and the light occurs for a relat,ively long period of time. This mixture produces a characteristic blue color: fluorescein and rhodamine B may be added to obtain green and pink light. Instructions for this and other variations of chemiluminescent. demonstrations as well as the necessary materials are available from the Shawe Science Club, Shawe Memorial High School, 201 State Street, M a d i s a , Indiana.
DEMONSTRATION
Place a t,easpoonfulof the mixture (about 5 g) and a cup of water (about 250 ml) in a pint jar. When sealed, this may he passed among students.
CHEMICAL EQUILIBRIUM Submitted by: S. B. Butler, Queens College, Flushing, New York Checked by: Roger Wheaton, Michigan St,ateUniversit,~, East Lansing PREPARATION
Obt,ain a Soxhlet extractor which empties the extract,ion chamber when 50 ml liquid has been collected. Prepare a mixture of 10 m10.5 M CoCI2solut,ion, 90 ml saturated NaCl solution, and 125 ml water. Place 120 ml of t,his mixture in the flask of the Soxhlet apparat,us: save t,he rest for color comparisons. The boiling flask should he strongly illuminated. DEMONSTRATION
The Cobalt Chloride Complex-Set t,he Soxhlet, extraction apparatus into operation by heating t,he flask. The solution in the flask will turn blue when the upper chamber is filled about halfway to the point where it siphons back. When it cycles, the solution becomes red again. REMARKS
Once prepared, the solution may be used or stored indefinitely. It should be tried out inadvance, since minor adjustments in concentration may be necessary. Small Soxhlet extractors argpreferred in order that they may
cycle within a period of 6-8 min. The equilibrium reaction may be repeated any number of t,imes without interference by the lecturer. These reactions t,ruly observe the laws of equilibria; it should be not,ed that t,he ratios between the reactants, the volume of the mixture, and the quantity of water removed are not greatly altered. The blue color is characteristic of a chloride complex of Co(II), the pink of a more highly hydrated form. ALTERNATIVE PROCEDURE
The Hydrolysis of Bismuth Chloride-The same apparatus may be used with a BiCh solut,ion (add 5 g BiClZ to 10 ml 6 N HC1, warm, and dilute to 130 ml with HzO). Witah this solution boiling stones will be necessary (carborundum chips work well), and the composition should be adjusted by adding very small amounts of acid or water so that the solution in the boiling flasks becomes clear about halfvay through the cycle. The mixture is very sensitive to the acid concentration. Jatrmal 01Chemical Edl~colion
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