Submitted by: Prem Behari Mathur, Central Electrochemical Reseaich Institute, Karaikudi, India Checked by: David B. Moss and Dale Ureisbach, Hiram College, Hiram, Ohio
PREPARATION
REMARKS
Obtain copper(I1) sulfate crystals, 0.5 mesh (1 c'm) or larger, if available, sodium chloride powder (fine crystals), a large circular glass jar, 12 in. in diameter, a filter paper also 12 in. in diameter, an iron plate 11 in. in diameter, and a wooden lid to fit inside the jar.
If properly insulated, the system maintains itself a t about 39'C due to heat of reaction. The size of copper crystals depends on the size of the copper sulfate crystals, being larger if larger sulfate crystals are used. For preservation, the copper crystals should be washed with water then concentrated sulfuric acid and kept. in dilute sulfuric acid solution. The metal obtained by this process is usually highly pure. The process is general and may he used to recover mercury using magnesium(I1) chloride as foreign electrolyte, gold using sodium sulfate with silver as the reductant, silver using sodium siilfate with copper as the reductant. References: DHOZDOV, .J. Awl. Chem., VSSR, 31, 202, Eng. trans. (1958). P. B. A N D MATHUR, R. B., Indian Pat. No. MATHUR, 67635, May 11, 1959.
DEMONSTRATION
Spread a layer of the copper sulfate ciystals on the bottom of the jar. Cover this layer with sodium chloride powder, place the filter paper over the salt, and put the iron plate on top of the paper The jar is carefully filled with a saturated solution of sodium chloride up to about 1.5 in. above the iron plate, and the wooden lid is allowed to float on the liquid to reduce heat loss. Within 24 hours brilliantly shining crystals of copper metal arc seen instead of copper sulfate crystals.
Journal
of Chenncal Education
.
foaember 1962
COMMON ION EFFECT Rewritten from: "Lect~ureDemonstrations in Chemistry-1" by .I. F. Hazel, University of Pennsylvania Checked by: Roger Wheaton, Michigan State Vnivcrsity, East Lansing
PREPARATION
DEMONSTRATION
Provide two 250-ml volumetric flasks, tvio rubber balloons, finely granulatedm agnesium (70-80 mesh), 3% acetic acid solution, and solid sodium acetate. Place 2-grams magnesium in each of the balloons and I50 ml of the acetic acid solution in each of the flasks To one flask add 10 to I.% of sodium acetate and shake to dissolve.
Place the neck of a balloon over each of the flasks and bind with a rubber band. Simultaneously raise the balloons to spill the metal into the flasks. Hydrogen will be produced and will fill each balloon to a diameter of .5 or 6 in. The buffered solution will require a longer time but will ultimately (5-10 min.) produce the same volume of hydrogen.
