B. Fluorine Dem. 596-Etching
Glass with HF
Materials: Mp box, stopper hearing 13 X 100 mm test tube; bleaching powder (chlorinated lime, CaOCL); dry ice, acetone, dil. HC1.
Etching of glass by HF. Reaction: 4HF 2H20 SiF, (gas).
+
Procedure: Project Mp box with valve open. Put in 10 g of bleaching powder lumps, add 10 ml dil. HCl. Stopper with test tube filled with acetone-dry ice mush.
Materials: CaF2, conc. H2S04, a small lead dish or folded lead-foil 11/*-in. in diameter; 4 X 4-in. glass plate.
Observations: Yellowish green chlorine gas is given off; it liquefies on, then drips off, the cold test tube in the Mp box.
Experiment developed by Raymond P. Garman. To show:
+ SiOz (in glass)
-
Procedure: T o 2 g of CaFz in the lead dish add 2 drops of H20, then 2 ml conc. H2S04;stir with a matchstick to a paste. Using the matchstick as a pen, write "HF" on the glass plate. Leave for 30 min. Now rinse off with water and project. Observations: Reference: (1936).
"HF" is etched into the glass.
ROOKHEIM, A,, J. CHEM. EDUC., 13, 93
C. Chlorine 1. ELEMENTAL CHLORINE a . Preparation of Chlorine Dem. 597-Chlorine
by Electmlysis [liquefaction)
Experiment developed by Raymond P. Garman. To show:
Preparation of chlorine by electrolysis of salt.
Materials: E-1, culture tube, NaC1-aq, dry ice, acetone, H-3 box. Procedure: Fill E-1 with NaC1-aq, insert Pt electrodes; invert culture tube full of NaC1-aq over the positive electrode. Project. Pass current to fill culture tube with Clz gas. Project H-3 box quarter filled with acetone-dry ice mush. Immerse culture of Clzinit. Observations: Chlorine gas is generated; it is not sufficiently colored to show in projection. However, it liquifies to deep yellow in the acetone-dry ice.
C. W., J. CHEM. EDUC., 2, Reference: ANDERSON, 715 (1925). Dem. 598-Chlorine
by Electmlyrir [bleaching)
Reaction:
CaOCl,
+ 2 HC1-
CaClz
+ H 2 0 + Cl,,
F. C., J. CHEM.EDUC., 12, Reference: KRAUSKOPF, 293 (1935). Dem. 600--Chlorine from Halozone and mdm Chloramine-T
Experiment developed by Raymond P. Garman. To show: Preparation of chlorine from halozone tablets and from chloramine-T. (The former are used to disinfect drinking water, the latter used chiefly in surgical dressings.) Materials: Halozone tablets, chloramine-T; dil. HC1, KI-aq, CS*, H-3. Procedure: I n H-3 project 2 culture tubes containing 10 ml ICI-aq. Into tube I drop a halozone tablet. Into tube 2 drop 0.1 g chloramine-T, then a dropperful of dil. HCl. Shake. Now add 10 ml of CSz (CARE: fire hazard) and shake. Observations: Both halozone and acidified-chloramine-T liberate chlorine, which displaces the iodine in K I to color water brown and CSI violet. References:
GERSTENZENG, E. M., J. CHEM.EDUC.,
8, 1187 (1931); 9, 318 (1932); SUSSMAN, S., ibid, 9,
1652 (1932). ~okmulas: Halozone is HOOC-CBHs. SOz.NCL, p(n,n-dichlorosulfamyl) benzoic acid. CH3-CsHS,Na Chloramine T, also called chloramine, ,C1-, is sodium p-toluene sulfon chloramid. Dem. 6 0 1-Chlorine
h n KMnOa
+ HCI
To show: Formation of Clzduring electrolysis of NaCIaq. Materials: Red dye, NaC1-aq, E-1, dc source.
To show: Generation of Clz by the interaction of I
