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Unformatted text preview: 10/12/11 1 Gravimetric Analysis Gravimetric analysis uses the mass of a sample to determine the amount of substance of interest Precipitation is the most common form of gravimetric analysis: Ag + (aq) + Cl- (aq) → AgCl(s) Since K sp is small (K sp [AgCl] = 1.8 x 10-10 ) most of the silver will be removed from solution in the form of precipitate From molecular formula and mass of AgCl, amount of Ag + originally in solution can be calculated Gravimetric Analysis Accuracy depends on several factors: 1. Value of K sp —if K sp is larger, more analyte will remain in solution and not be included in mass of precipitate 2. Crystal formation—crystals grow in two stages 1. Nucleation—rapid combination of molecules to form nanoscale aggregates 2. Particle growth—addition of more molecules to form “ macroscopic ” particles larger than μ m scale Gravimetric Analysis Potential problems with particle formation 1. Colloid formation—a colloid is a nanoscale particle (diameter < 1...
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This document was uploaded on 11/17/2011.
- Fall '09