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Updated: June 5, 2025
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.
To understand the changes which occur when solids are dissolved where chemical action is involved, it should be remembered that no substance is completely insoluble in water, and that those products of a chemical change which are least dissociated will first form. Consider, for example, the action of hydrochloric acid upon magnesium hydroxide.
So it was now urgent to renew the air in our prison, and no doubt the air in this whole underwater boat as well. Here a question popped into my head. How did the commander of this aquatic residence go about it? Did he obtain air using chemical methods, releasing the oxygen contained in potassium chlorate by heating it, meanwhile absorbing the carbon dioxide with potassium hydroxide?
!Answer!: 74.18 cc. One gram of crude ammonium salt is treated with strong potassium hydroxide solution. The ammonia liberated is distilled and collected in 50 cc. of 0.5 N acid and the excess titrated with 1.55 cc. of 0.5 N sodium hydroxide. Calculate the percentage of NH in the sample. !Answer!: 41.17%.
Loose plugs of cotton are placed at the top of each arm and between the soda lime and the calcium chloride. A small tube containing calcium chloride is connected with the Geissler bulb proper by a ground joint and should be wired to the bulb for safety. This is designed to retain any moisture from the hydroxide solution.
Professor Moore stood stoutly for the older views, and "believed that he could demonstrate a step which connected inorganic with organic creation." Then he gave an abstruse and highly technical account of a process by which in "solutions of colloidal ferric hydroxide, exposed to strong sunlight," compounds could be formed similar to those to be found in the green plant.
!Ignition of the Iron Precipitate! Heat a platinum or porcelain crucible, cool it in a desiccator and weigh, repeating until a constant weight is obtained. Fold the top of the filter paper over the moist precipitate of ferric hydroxide and transfer it cautiously to the crucible.
How many grams of pure potassium hydroxide are required for exactly 1 liter of normal alkali solution? !Answer!: 56.1 grams. A sample of aqueous hydrochloric acid has a specific gravity of 1.12 and contains 23.81 per cent hydrochloric acid by weight. !Answers!: 0.2667 gram; 7.307 milliequivalents. !Answer!: 76.33 cc. A given solution contains 0.1063 equivalents of hydrochloric acid in 976 cc.
Of sodium and potassium hydroxide, it may be said that they can be used with all indicators, and their solutions may be boiled, but they absorb carbon dioxide readily and attack the glass of bottles, thereby losing strength; sodium carbonate may be weighed directly if its purity is assured, but the presence of carbonic acid from the carbonate is a disadvantage with many indicators; barium hydroxide solutions may be prepared which are entirely free from carbon dioxide, and such solutions immediately show by precipitation any contamination from absorption, but the hydroxide is not freely soluble in water; ammonia does not absorb carbon dioxide as readily as the caustic alkalies, but its solutions cannot be boiled nor can they be used with all indicators.
This indicator cannot, however, be successfully used with weak bases, even ammonium hydroxide; for, since it is weak acid, the salts which it forms with weak alkalies are easily hydrolyzed, and as a consequence of this hydrolysis the change of color is not sharp. This indicator is affected by even so weak an acid as carbonic acid, which must be removed by boiling the solution before titration.
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