WASHING THE PRECIPITATE: A precipitate may be washed directly on the filter, or it may be washed partly by decantation and partly on the filter. If by decantation, the precipitate is allowed to settle, and the supernatant liquid is poured on the filter. Wash water is added to the precipitate, and after settling, the decantation is … Read more
Material of Vessels for Solution The student must consider the effect of the solvent used on the vessel. In most cases the solvent used is an acid or mixture of acids, and for such solvents glass and porcelain are generally used. Platinum may be used, provided no chlorine or other attacking agent be present. (See … Read more
Analytical Balance Principle In this place it will be sufficient to describe the usual chemical balance, designed to carry in each pan a load up to 100 gms. This balance can be obtained at a reasonable figure, and sensitive to 1/10 of a milligram (0.0001 gm.). In the section on Assaying the student will find … Read more
FIG. 35 gives an idea of the spectroscope and of its different parts. P is a flint glass prism, having a refracting angle of 60° and resting on a brass plate fixed on a brass support, S. The brass plate carries the collimator tube C, in the end of which nearest to the prism is fixed … Read more
PREPARATION OF SOLUTION FOR BASES 1. Boil the finely-divided substance in distilled water. 2. If insoluble, add ¼ its bulk of strong HCl and boil for two or three minutes. 3. If still insoluble, treat a fresh portion with strong HCl and boil for five minutes ; then add an equal volume of water and warm. The … Read more
Note 1. Do not boil with Na2CO3 unless necessary. If only alkalies are present it is unnecessary. Note 2. If organic acids and Groups I. and II. or H2CrO4 are present add HCl, and pass H2S before boiling with Na2CO3 to make solution (4). The following should be tested for separately:— HNO3.—Black ring test, with … Read more
Take a few crystals of potassium chlorate (KClO3), place them in a clean dry test-tube, and heat them gently over a small bunsen flame; the salt begins to split, then fuses. Insert into the test-tube a splint of wood, glowing at the point, but do not allow the wood to quite touch the fused salt. The splint, which … Read more
Before starting to work at Practical Chemistry it is necessary that the student should have some knowledge of how to cut, bend, draw down, and round off the ends of glass tubing, make closed and bulbed tubes, mend test- tubes, top and bottom, and fit up a decent wash-bottle. In this chapter is included also … Read more
The measurement of the strength of an acid by the quantity of alkali required to neutralise it (termed acidimetry), and the measurement of the strength of an alkali by the quantity of acid required to neutralise it (termed alkalimetry), will be considered in this chapter. The student is asked to determine volumetrically: THE ESTIMATION OF … Read more
When we consider the ordinary gravimetric precipitations, it is evident that if the exact strength (as regards precipitation) of the precipitating reagent Apparatus, Reagents.—Apparatus as usual. For the preparation of the standard solution, pure silver nitrate (preferably triple crystallized) is required. For practice in this analysis the student may first estimate the chlorine in pure … Read more