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It is therefore destroyed by the addition of acid, and the solution is then made neutral with the solution of bicarbonate, part of which reacts with the acid, the excess remaining in solution. The reaction during titration is the following: Na AsO + I + 2NaHCO > Na AsO + 2NaI + 2CO + H O
If, however, it is recalled that normal solutions are equivalent to each other, it will be seen that the same result may be more readily reached by dividing the weight in grams of sodium carbonate per cubic centimeter just found by titration by the weight which would be contained in the same volume of a normal solution of sodium carbonate.
These, insoluble in water, amounted to 93.94 per cent, of the fat taken. The proportion dissolved in the water used for washing was estimated by titration with alkali; the quantity of KOH required was insignificant, equaling 0.71 per cent, of the fat originally used. This portion was not further examined. The insoluble fatty acids amounted, as last stated, to 93.94 per cent.
It is the indicator most generally employed for the titration of organic acids. In general, it may be stated that when a strong acid, such as hydrochloric, sulphuric or nitric acid, is titrated against a strong base, such as sodium hydroxide, potassium hydroxide, or barium hydroxide, any of these indicators may be used, since very little hydrolysis ensues.
We can of course also determine the titration for manganese in a chameleon solution with the greatest certainty by titrating a compound of manganese with an accurately estimated content of it, for instance, a spiegeleisen or ferromanganese; the test is carried out in the following way: The substance, which is to be examined for manganese, is dissolved by means of hydrochloric acid.
The liquid must be cold at the time of titration and entirely free from nitrous compounds, as these sometimes cause a reddening of the indicator solution.
The oil appears, from some experiments which I made, to be a mixture of a glycerine salt and a cholesterine salt of fatty acids. It distills without much decomposition, giving a brown-yellow oil, which fluoresces strongly, and has a somewhat pungent smell. The molecular weight was determined by saponification with alcoholic potash, and subsequent titration of the excess of potash employed.
Kolloide!, 10 , 132-146. A good grade of material should be secured. It can be successfully used for the titration of hydrochloric, nitric, sulphuric, phosphoric, and sulphurous acids, and is particularly useful in the determination of bases, such as sodium, potassium, barium, calcium, and ammonium hydroxides, and even many of the weak organic bases.
As in the case of the bichromate process, it is necessary to reduce the iron completely to the ferrous condition before titration. The reducing agents available are zinc, sulphurous acid, or sulphureted hydrogen. Stannous chloride may also be used when the titration is made in the presence of hydrochloric acid.
From this we also see how advisable it is to stir the liquid frequently during titration. Toward the close of it, it is also advantageous, when the contents of manganese are large, to warm the solution to about 50 deg. C., because the removal of color is thereby hastened.
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