Le Chatelier's Principles-Conductivity of Solutions Submilled b!j: Philip Kasimer, Quinnipac College, Hamdrn, Conn. OG51S Checked by: Arthur hIcE. Smith, Humholdt State College, Arcata, Calif. 95521 Preparalion
Remarks
Set up a standard ac conductivity apparatus using a 50-75 W bulb. Provide 100 ml of distilled water in a 250 or 400-ml beaker, a 2-5 g strip of magnesium ribbon, and 10 ml of glacial acetic acid.
Explain the observed intensities on thc basis of thc ions in solution in the two instances. Compare the first situation i~ivolvingonly concentrated acetic acid and its limited io~~izntion with the second one in which the magnesium is replacing hydrogen and providing acetate ions as \ d l as Mg2+ions. The reaction is not very vigorous. Cautiow: The maguesium strip must not touch the electrodes. NOTE: Refer to Tested L)enaoi~stralioi~s,by Alyea and Dutton, (6th Ed.), p. 15 and 74 for additional demonstrations.
Demonstration
Connect the apparatus, add glacial acetic acid, and observe the intensity of the light. Next add the strip of magnesium and again note the intensity of the light. Is there any additional indication of a chemical reaction?
Volume 47, Number 6, June 1970
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A439
