The document discusses the theory and process of gravimetric analysis. Gravimetric analysis involves selectively converting the analyte to an insoluble form through precipitation, drying, and weighing. Key steps include preparing a soluble solution of the analyte, precipitating it using a reagent under controlled conditions, filtering and washing to separate and purify the precipitate, drying and igniting the precipitate, and calculating the analyte amount by weighing. Factors like supersaturation, precipitation temperature and pH, and washing properties influence the purity and size of precipitate crystals formed.

1. B.Sc.V Semester Paper-II
INORGANIC CHEMISTRY
1. Theory of gravimetric analysis: 4 hrs
• Principles of gravimetric analysis- super saturation,Von-Weimann equation
conditionsof precipitation,co-precipitationand post precipitation,separationof
precipitatefrom mother liquor,washing properties of washing liquid,drying,
ignitionof precipitateand weighing form.
2. Industrial Chemistry:
a) Alloys:Significance,Types of alloys (ferrous and non-ferrous alloys) 2 hrs
preparation (fusion and electro-deposition)and their applications.
b) Abrasives:Hardness, manufacture and importance of carborundum, 2 hrs
alundum,tungsten carbide.
c) Glass: Raw materials, manufacture,types, compositionand uses. 2 hrs
d) Cement: Raw materials, manufacture and mechanism of setting. 2 hrs
f) Nanomaterials:Introduction,preparation,charactersand applications
(sensors) . 2 hrs

2. Theory of gravimetric analysis
• Gravimetric analysis is the most accurate and precise methods of
quantitative analysis in which the analyte is selectively converted to an
insoluble form i.e precipitated , dried or ignited to a suitable weighable
form .
Specific steps involved in Gravimetric analysis are
➢ Preparing the suitable solution containing analyte in soluble form.
➢ Precipitation of analyte under suitable conditions using a specific
preciptating reagent (in slight excess).
➢ Digestionof ppt for the growth of ppt particles.
➢ Filtration of solution to separate the analyte.
➢ Washing of analyte / ppt to remove adhering impurities.
➢ Drying of ppt/analyte to remove moisture and adsorbed impurities at
temprature 110 oC - 120 oC .
➢ Ignition at higher temperatures 500oC- 900oC
➢ Weghing
➢ Calculation.

3. Step 1 Preparation of solution
• A preliminary separation is necessary to eliminate interfering
materials.
• Adjustment ofsolution conditions before precipitation.
Factors to be considered are :-
1. Volume of solution
2. Concentration range of analyte or test substance.
3. Presence of other constituents.
4. Concentration of other constituents
5. Temperature of solution
6. pH of solution.

4. Precipitation
After preparing solution next step is precipitation , certain conditions are important.
➢ The precipitate must be sufficiently insoluble such that solubility of precipitate is
negligible.
➢ Precipitate must contain large crystals that are easily filtered [precipitate tend to carry
some of the other constituents of the solution with them. This contamination should be
negligible.
➢ Von Weimarn discovered that particle size of precipitate is inversely propotional to the
relative supersaturation of the solution during the precipitation process .
Relative supersaturation = Q - S
S
Q- concentration of mixed reagents before precipitation and it is the degree of
supersaturation.
S- solubility of precipitate at equillibrium
This ratio is Von Weimarn equation

5. ➢ When a solution is supersaturated it is in a state of metastable equilibrium . Which
favours nucleation to give a large particles i.e a minimum number of particles come
together to produce microscopic nuclei of the solid phase.
➢ Higher the degree of supersaturation greater is the rate of nucleation and produce
more total crystals of smaller size.
➢ However if the crystal surface area is larger the impurities are adsorbed . Also the
increased growth rate of crystals increase the possibility of imperfections in the
crystal and trapping of impurities.

6. Conditions of Complteness of Precipitation
1. Precipitation must be carried out in dilute solutions which minimise the content of
impurities ( coprecipitation ) .
2. The prcipitating agent is added dropwise , in slight excess , eith constant stirring
such that large are regular / perfect shaped crystals are formed and supersaturation
is controlled.
3. Precipitation is carried out in hot conditions ( 60 oC - 80 oC ) provided precipitate is
stable .
4. The effect of co-precipitation and post precipitation (impurities) are overcome by
dissolution and reprecipitation.
5. The purity of precipitate depend upon the nature of precipitate and also conditions
of precipitation.
6. In case of curdy precipitates impurities are adsorbed on the primary particles these
can be easily removed.