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Updated: June 21, 2025
Dissolve 3 grams of sodium bicarbonate in 200 cc. of water in a 500 cc. beaker, and pour the cold solution of the antimony chloride into this, avoiding loss by effervescence. This is usually expelled by the heating upon the water bath; but if it is not wholly driven out, a point is reached during dilution at which the antimony sulphide, being no longer held in solution by the acid, separates.
"Maju torna, maju veni Cu li belli soi ciureri; Oh chi pompa chi nni fa; Maju torna, maju è cc
How many cubic centimeters of 3 N phosphoric acid must be added to 300 cc. of 0.4 N phosphoric acid in order that the resulting solution may be 0.6 N? !Answer!: 25 cc. !Answer!: 0.2835 N.
If a sample of silver coin weighing 0.2500 gram gives a precipitate of AgCl weighing 0.2991 gram, what weight of AgI could have been obtained from the same weight of sample, and what is the percentage of silver in the coin? !Answers!: 0.4898 gr.; 90.05%. !Answer!: 47.03 cc. What will be the weight of the ignited precipitate? !Answers!: 2.26 cc.; 0.2154 gram. !Answer!: 0.80 cc. !Answer!: 2.63 cc.
PROCEDURE. To the filtrate from the insoluble residue add ammonium hydroxide until the solution just smells distinctly of ammonia, but do not add an excess. If the smell of ammonia has disappeared, again add ammonium hydroxide in slight excess, and 3 cc. of bromine water, and heat again for a few minutes. A brown residue insoluble in the acid may be allowed to remain on the filter.
The balance, CC', whose accuracy contributes much to the stability of the whole in the air, consists of a string fixed at one end to the junction, D, of the bow and stick, and at the other to the stick itself at a distance of three units from the lower extremity. Next, a cord, B, is passed around the frame, and the whole is covered with thin paper.
Test a portion of the last washing with a dilute solution of ammonium sulphide to assure complete removal of the zinc. The precipitate may then be ignited and weighed as ferric oxide, as described on page 110. PROCEDURE. Acidify the filtrate from the iron determination with dilute nitric acid. Concentrate it to 150 cc. It is important that this point should not be overstepped.
It may be employed with some of the stronger organic acids, but the use of phenolphthalein is to be preferred. !Hydrochloric Acid and Sodium Hydroxide. Approximate Strength!, 0.5 N PROCEDURE. Measure out 40 cc. of concentrated, pure hydrochloric acid into a clean liter bottle, and dilute with distilled water to an approximate volume of 1000 cc.
Burettes may also be calibrated by drawing off the liquid in successive portions through a 5 cc. pipette which has been accurately calibrated, as a substitute for weighing.
Weight of sample 1.000 gram; volume of 0.25 N hydrochloric acid required for phenolphthalein end-point, 26.40 cc.; after adding an excess of acid and boiling out the carbon dioxide, the total volume of 0.25 N hydrochloric acid required for phenolphthalein end-point, 67.10 cc. !Answer!: 69.95% Na CO ; 30.02% NaHCO .
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