Experiment 16 Gravimetric Analysis

The amount of a substance present in a sample is determined by taking a solution containing that substance and precipitating a compound containing that substance. The precipitate is then dried and weighed. (See the Stoichiometry chapter.) 

Equipment analytical balance beaker(s) crucible and cover 

Meker burner support stand triangle crucible support 

Excess (unmeasured) reactant is added to the solution to form a precipitate. 

The crucible and cover containing the dried precipitate are weighed. 

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This experiment describes the use of a fractional factorial design to examine the effects of volume of HNO3, molarity of AgN03, volume of AgN03, digestion temperature, and composition of wash water on the gravimetric analysis for chloride. 

Experiment 4 Practice of Gravimetric Analysis Using Physical Separation Methods... 

Particular attention should be paid to both the stability in solution and the thermal stability. The condesation-hydrolysis equilibria of heteropolyanions in aqueous media are shown in Fig. 8. Each heteropolyanion is stable only at pH values lower than the corresponding solid line (55). Some solid heteropolyacids are thermally stable and applicable in reactions with vapor-phase reactants conducted at high temperatures. The thermal stability is measured mainly by X-ray diffraction (XRD), thermal gravimetric analysis, and different thermal analysis (TG-DTA) experiments. According to Yamazoe et al. (56), the decomposition temperatures of H3PM012O40 and its salts depend on the kinds of cations Ba2 +, Co2+ (673 K) < Cu2+, Ni2+ (683 K)[Pg.127]

The chlorine content of Polymer Fractions I, II, and III was determined by gravimetric analysis and found in all cases to be within 1% of the value for undegraded poly (vinyl chloride). (Since it was difficult to remove the last traces of solvent, the actual chlorine content of the polymers was probably even closer to the theoretical value.) The chlorine content of the insoluble residue was much lower. Thus, the insoluble residue of samples obtained from the experiments illustrated by Table III contained typically only 46-49% Cl. 

Gravimetric analysis is a technique for determining the identity of a compound and/or the concentration of a solution by measuring mass. Gravimetric experiments often involve precipitation reactions. 

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