Gravimetric Analysis of a Soluble Chloride

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Objective: To perform gravimetric analysis of silver chloride and calculate the percent chloride in the sample. Introduction: Gravimetric analysis is based on the quantitative isolation of the desired constituent—the analyte of interest, from the sample in highly pure form or in some combined form and weighing the isolated constituent. The desired constituent is usually isolated or separated by precipitation. From the masses of sample and precipitate, the percentage of the constituent in the original sample can be calculated. Precipitation is effected by organic or inorganic precipitating agents. Two common inorganic precipitating agents are silver nitrate, which is used to precipitate halide ions such as chloride and barium chloride, which is used to precipitate sulfate ion. In these precipitate reactions, the product is a salt because it is formed by reactions between cations and anions. The three major requirements for a good gravimetric analysis are: the reagent will react only with the analyte of interest to form a precipitate, it forms one and only one product with the analyte and the analyte precipitates quantitatively from solution. In aqueous solution silver ion undergoes the following reactions with chloride: Ag+ (aq) + Cl- (aq) ↔ AgCl (s) Experimental Methods: Three crucibles were thoroughly washed with soap and water. The cleaned crucibles were then mounted to a filter flask, and 2 mL of concentrated nitric acid were allowed to soak. The acid was drained via a gentle vacuum. This was repeated 2 more times. The crucibles were then rinsed with deionized water. Three portions (0.316g, 0.305g, and 0.298g) of dried chloride sample were dissolved in 3 separate 400 mL beakers in 150 mL of deionized water and 1 mL of concentrated nitric acid. The three chloride solutions were then heated, and silver nitrate solution was added in 5 mL increments (while

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