CHROMATOGRAPHY: INORGANIC SEPARATIONS USING CHALKBOARD CHALK Submitted by: Pard M . Lauren, Forest Hills High School, Forest IIills 75, N. Y. Adapted from: J. M . Saurer,
T E I ~JOURNAL, 40,
A535 (1963)
Cheeked by: David Onaga and Edward S. Jenkins, NSF Chemistry Institute, Montana State College, Bozeman
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PREPARATION
Prepare 10 ml of a cation mixture from equal volumes of 0.1 ill eat,ion solntions, and place t,he mixture in a 50;ml beaker. Let a stick of white chalk (Binney and Smith No. 307 or equivalent) stand in the mixture I S 1 5 mi". Using forceps, remove the chalk and expose it to a source of ammonia or HIS or both. The qninol-Hi? clathrate compomd' is a convenient source of &S. Place the chalk in a test tube and add a small amount of the clathrate to the bott,om of the tube. Lighbly stopper the tube and gently heat the bottom of the test tube with a lighter. DEMONSTRATION
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0.1 M FeCls The chalk will acquire a narrow dark yellow hand after l(t15 minutes in the mixture. Wheu exposed to the vapors of conc N I 4 , a dark blue zone will farm above the yellow hand. The color of the copper-ammonia complex can be demonstrated by adding NHJ to the CuS04. Do the same wish the FeCL and the mixture. Mizlzcre B: 0.1 M FeCIa 0.1 M Cd(N03)? A dark narrow band midway up the chalk appears on immersion. Exposure to H B produces a. light yellow zone above the yellow band.
illizture A : 0.1 M CuSOd
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Mizture C: 0.1 M HgCL 0.1 M CuS04 No visible band appears. When exposed to NHa, a dark b h e aone is produced near the top. H2S produces a black zone helow the blue one. ddizture D: 0.1 df HgCh 0.1 M FeC& A narrow dark yellow band appears on immersion. H.S produces a. dark brown zone above a. white one in whirh the narrow dark yellow aone lies. ~ i z t E: ~ ~0.1eM H ~ , ( N o I ) ~ 0.1 M CIISO~ No visible bands appear. Exposure to NH3 prodnces a dark blue upper zone and a black lower one. Mtiture F: 0.1 M Cd(NO1)$ 0.1 M HgCI? No visible bands appear. H d produces a light vellow zone near the top and a brown zone near-the bottom.
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REMARKS
The results obtained from these demonstrations may be eompared with those from similar treatment of test tube quantities of the cation aolntion and the test mixture.
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ALYEA,HUBERT,A N D DUTTON,FREDERIC,"Tested Demonstrations in Chemistry," 6th edit,ian, Chemical Edueat,ion Publishing Co., East,on, Pennsylvania, 1965, p. 162.
J O U R N A L OR CHEMICAL EDOCATIDN
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APRrL
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