Лаборатория иши №5

Weighing results:Mass of bucks with salt, g. Mass of bucks with salt load, g. The mass of salt in the flask, g.
The following formula is used to calculate the analysis results:

here,
NB - normality of sodium hydroxide solution;
EA - molar mass of detectable ammonia equivalent, 17.03;
f- aliquot multiplier;
VB - volume of spent alkaline solution, ml;
a is the mass of the sample, g.
If the mass fraction of ammonia in the sample is close to or the same as any salt of ammonia, an appropriate conclusion is drawn about the formula of the salt under test. Absolute and relative errors are found on the basis of the values ​​obtained from the teacher with the mass fraction obtained as a result of the analysis of ammonia

LABORATORY WORK №5

Obtaining gypsum-based binding products.
Purpose of work:Study of the process of production of binding products from phosphogypsum binder, which is a waste of mineral fertilizers.

THEORETICAL INFORMATION.

Gypsum binders. Gypsum binders are formed by grinding burnt gypsum (gypsum stone consists mainly of calcium sulfate CaSO4 • 2H2O, which contains two molecules of water). Depending on the temperature and conditions of firing, gypsum is formed from gypsum, solid gypsum and anhydrous cement.
Construction plaster. Calcium sulphate sedimentary rock, which contains two molecules of water, is obtained by cooking gypsum (CaSO4 • 2H2O) and anhydrous rock (CaSO4), called anhydrous gypsum, as well as some industrial wastes. The standard states that the production of the first navgips requires a natural gypsum stone with a content of CaSO4 • 2H2O of 90%, and for the second grade not less than 65%.
Natural gypsum stone is a white rock with a hardness of 2 (on the Moos scale) and a density of 2200 - 2400 kg / m3. The largest reserves of gypsum are in Bukhara region (Kogon gypsum deposit).
150 -170 ° CThe product obtained by grinding gypsum stone fired at a temperature is called construction gypsum.
Calcium sulfate, which is two molecules of water65 ° CWhen heated at, it changes its properties and the water in it gradually disappears and begins to dihydrate. In this case, the gypsum stone loses 1.5 molecules of water and turns into half a molecule of aqueous gypsum, which is characterized by the following reaction: