Tested Overhead Projection Series Compiled by HUBERT N. ALYEA Princeton University
GROUP VII.
20. 1.
permit gas to escape.) Also fasten a small cone of wax on the lower t,ip of the test t,ube, as shown. KNnO4, conc. HC1 (DANGER: do not use HzSO,).
THE HALOGENS
Procedure: Omit vial A . Place 5 g 1iMnO4in vial B and into it run 5 ml of conc. HC1. Stopper at once with the tube-bearing stopper.
ELEMENTAL CHLORINE
a. Preparation of Chlorine (Continued) Dem. 602-Chlorine
from KCIO,
Obseivafzons: CL gas is generated (Dem. 601), solidihes on the test tube, melts and drips off the wax cone The cycle repeats
+ HCI
Experiment developed by Raymond P. Garman.
-
To show: The preparation of chlorine gas from KC1Oa HC1. SKC10, 24HC1 8KC1 12Hs0 9C1. 6C10,.
c.
Materials: KC103, dil. HC1, Mp box with stopper bearing a 13 X 100 mm test tube; dry ice, acetone.
To show: The photochemical combination of chlorine with hydrogen
Procedure: Project Mp box with valve open. Put 5 g KC103 in box, then 10 ml dil. HC1. Insert stopper with test tube holding acetone-dry ice mush.
Materzals: Plastic vial about 4-111 long, 1-m diam; tray about ,5' X l l j s X 2-in.; X g ribbon, forcepi-i,GIsga-i, Hs-gas.
Observations: Cl, gas is generated; it liquefies on, and drips off of, the cold test tube in the Mp box.
Procedure: Protect the projector stage by placing a 6 X 6 X l/s-irl. sheet of Plexiglas over it. Fill the vial wit,h water, inverted in water in the t,ray. Pass pure Clz to displace half of the water in the vial, and pure Ha to displace the remainder. Project, with the lamp off. Turn on the lamp. If necessary, bring burning AIg ribbon (CARE) up to the inverted vial containing t,he Cis Hz.
+
+
+
+
+
b. Physical Properties of Chlorine Dem. 603-Density
of Chlorine
Dem. 605-Phatochemical:
H,
+ CI;
+
Experiment developed bg Carl J Mancuso. To show:
Reactions of Chlorine
Chlorine g'iihis heavier than air
Materzals: A 4-02 narrow neck clear-glass square bottle of Cia gas with a 1-hole stopper bearing 1-in. length of 7 mm tubing; SD4 hlmstrip~; KI-aq, starch-aq Procedure: Project bottle of Cl? to show yellow gas. Now project C-2. Dip film strip into KI-aq, then hang in cell 1. Dip a second strip into a mixture of KI-aq starch-aq, then hang in cell 2. Project C-1 with strips hanging in it Now tilt Cls-bottle so the 6 mm tubing can be seen at the mouth of cell 2.
+
Observations: POP! The combination may be violent (CARE).
+
+ +
+
Reactions: (a) Cl; light -+ CI Cl. (6) Cl H i - + HC1 H. (c) H Clz+ HC1 Cl. This is a chain reaetion, described in more detail in the next demonstration.
+
Dem. 606-Domino
+
Model of Chain Reaction
-
To show: The model of the reaction Cl
+ H;
-f
HC1
+ H, If + Cl;
HC1
+ Cl; etc
Observations: The chlorine gas is heavier than air (71 vs 29) and sinks into the cells. I t reacts with KI to liberate brown Is, and with KI-starch to give blue color. The progress of the Cis gas as it descends into the cells is clearly followed. Reference: THOMPSON, T. G., ,J. CHEM.EUUC.,20, 377 (1943). Dem. 604-Liquefaction
of Chlorine
To show: The formation, liquefaction, and vaporization of chlorine. Materials: Special Device SD-566, see Figure eonsisting of a 2-02 wide mouth bottle bearing a one-hole stopper holding a test tube containing dry ice-acetone mush. (File a groove along t,he side of the stopper to Volume 46, Number 4, April 1969
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