Tested Overhead Proiection Series Compiled by HUBERT N. ALYEA
Princeton University
20. GROUP VIII. THE HALOGENS
Procedure: Label each plastic strip with its respective fluid, e.g., INDIA I R K , MAGIC MARICER, etc. Project C-4 half-full of bleaching solution. Immerse the strips for 5 min. Compare extent of bleaching.
2. CHLORIDES
Observation: Inks containing graphite or carbon (e.g., India Ink, pencil, some ball-point inks) will not bleach; vegetable dyes often bleach).
Dem. 6 13-Hydrolysis
To shoa:
of FeC18
Thermally accelerated hydrolysis.
Procedure: I'roject H-3 with two oval tubes quarterfull of I'eCIJ-aq of equal concentration. Heat onc.
+
-
+
3H,O Fe(OH), 3 HCI. Observations: I"eC13 At first dark yellow ferric hydroxide forms, and then this forms rcd colloidal fcrric hydroxide sol.
Dem. 6 14-Hydrolysis
of TiCL
To show: Formation of TiO? from hydrolysis of TiClr in the air. Alate~ials: Bottle of TiCI,, two-hole stopper with glass tubing inserted; 1-ft length of rubber tubing on one.
Dem. 6 16-Bleaching
of Dyes
Experiment developed by Raymond P. Garman. To show: The bleaching of a dye (methyl violet) by chlorine-aq. Materials: Methyl violet, 6 X 3-in. strip of cellophane dipped into methyl violet-aq and dried; C-1, bleaching solution made up in one of the following ways. (a) Add dilute HCI t o Chorox until faintly acid, then filter and use the clear solution. (0) Mix hypochlorite bleaching powder with 3 times its volume of HzO; filter, use the clear solution. (c) Bubble Cl, gas into H20.
Procerlure: (a) Place bottlc of TiCL on vertical stage. Rcmovc st,opper. (0) Insert rubber stopper with tuhing in bott,le of TiCl,; blow through rubber tubing.
P~ocedure: Project C-1 colored strip into it.
Observalioiis: (a) Smolie pours from the bottle opcn to the air. (b) A jet of smokc issues from the tubing.
Obsewations: The half which dips into the CIz-aq is bleached; the upper half remains violet.
-
+ 4H10 in air + 2H2O.
Reactions: TiCl, Ti(OH), TiO, smoke
-+
Ti(OH),
+ 4HC1.
Note: Skywriling can be done with this; NHa is also ejected nnd unites with ihe HCI lo form white N H O smoke. Smoke sweena sro also made with fine particles of heated hydruearb~m uils.
Reference: (1956).
filled with CIS-aq. Dip the
WOLF, A I . G.,
Dem. 6 17-Bleaching
AND
RAPP, G., 33, 414
versus Solvent Action
Experimeut devised bg Raymond P. Carman To shozc: Difference between bleaching action and solvent action on two differenttypes of inks.
3. HYPOCHLORITE (Bleaching) Dem. 6 15-Bleaching
of Ink
Experiment developed by Raymond P. Carman To show: Bleaching action of chlorine on various inks and dyes. Bleachzng solution: N a d e up in any of the following ways. (a) Bubble chlorine gas into water. (b) Nix hypochlorite bleaching powder with three times its volurnc of water; filter, use the clear solution. (c) Add dil. HCI to Chlorox or otherblearhingsolution until faintly arid; filter and use clear solution. Materials: Rlcaching solution; India ink, ordinary hluc writing ink, Magic Alarlier, vegetable dye, ballpoint pen, pencil, grcase pencil, etc. Clear plastic in. Ccll C-4. stri[is, (iX a/n X
Afaterials: Ball-point pen, ordinary writing ink; C-2, two G X a/a X '/a-in. strips of plastic; clear chlorine water or the hypochlorite described in preceding demonstrat,ion; isopropyl alcohol. Procedure: Write BALLPOINT and OIZDINARY INK with the respective inks. Project C-2 with cell one 2 / a full of dilute chlorine water, and cell two 2/3 full of isopropyl alcohol. (a) Drop the ball-point ink strip into cell 1, and the other strip into cell 2 . I'roject for 2 min. (b) Now interchange the strips. Obsewations: (a) Some Ball-point inks are not affected by bleaching solution; the ordinary ink is not affected by the alcohol. (b) Upon interchanging, chlorine bleaches the ordinary ink, and alcohol dissolves the ball-point ink. Volume 46, Number 5, May 1969
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