IONIC VERSUS COVALENT BONDING Submitted by: Dorothy A t . Goldish, California State College, Long Beach, California Checked by: Francis V. Scalzi, Hiram College, Hiram, Ohio 44234
PREPARATION
OBSERVATION
Have available sodium chloride, benzyl chloride, 5% silver nitrate solution, 2 N sodium hydroxide, 95% ethanol, dil. nitric acid, 3 test tubes, and a burner.
The ionic sodium chloride dissolves in water, hut the covalent benzyl chloride does not. I n tube 1 an immediate precipitation of silver chloride shows the presence of ionic chloride. I n tube 2 no precipitate forms, showing that ionic chloride is not present. I n tube 3 some precipitate forms, showing that some chloride is present. Some chlorine is displaced from the covalent bond by the OH- from the sodium hydroxide.
DEMONSTRATION
Put 5 ml distilled water into tubes 1 and 2, and 5 ml of ethanol into tube 3. Add a little sodium chloride to tuhe 1and one-half milliliter of benzyl chloride to tubes 2 and 3. Add a few drops of silver nitrate solution to tubes 1 and 2, and compare results. Add 1 ml of sodium hydroxide solution to tube 3, boil 1 min, cool, and add nitric acid until acid to litmus. Now add silver nitrate to this tuhe and compare with tuhe 2.
REMARKS
Tube 2 will eventually show some precipitate, if it is allowed to stand, as the chloride is slowly displaced. As a control the procedure with tube 3 may be repeated with henzyl chloride being omitted. I n this case no precipitate will form.
Volume
46, Number 7, July 1969 / A497
