Lab Template for Lab 200:

The General Procedure for Gravimetric Analysis follows these basic steps:

Weigh the sample to be analyzed
Dissolve the sample in a suitable solvent, eg, water
Add an excess of the precipitating reagent to precipitate the analyte
Filter the mixture to separate the precipitate from the solution
Wash the precipitate to remove any impurities
Dry the precipitate by heating to remove water
Cool the precipitate in a dessicator to prevent the precipitate absorbing moisture from the air
Weigh the cooled precipitate
Repeat the drying and weighing process until a constant mass for the precipitate is achieved
Calculate the percent by mass of analyte in the sample

Gravimetric Analysis Calculation(s):

Example 1:

A 10.00 gram coin that contains silver was dissolved in nitric acid. When the solution cooled, the silver ions were precipitated out as silver chloride (AgCl) by the addition os excess chloride ion (Cl^-) being added. The precipitate was collected and dried. 12.75 grams of AgCl was obtained. Determine

the mass of silver in the coin

the percent silver in the coin

Example 2:

A 3.46 g sample of limestone(CaCO₃ ) was dissolved reacted in) in 0.1M (HCl) solution according to the following equation.

CaCO₃ (s) + 2HCl (aq) => Ca²⁺(aq) + 2Cl^-(aq) + CO₂(g) + H₂O (l)

Excess 0.1M (NH₄)₂C₂O₄(aq), was added to the resulting solution to precipitate the calcium ions as calcium oxalate, CaC₂O₄(s).

The precipitate was filtered, dried and weighed at 2.03 g. Determine:

the mass of calcium in the limestone

the percent calcium in the limestone

Reference(s)

Carlson, R. (2018, November 18). Silver coin gravimetrical analysis. Retrieved from https://www.youtube.com/watch?v=_hlr_Mwl4Mw
Carlson, R. (2018, November 18). Lab 200 Gravimetic Analysis limestone. Retrieved from https://www.youtube.com/watch?v=gDsgOyJJ3hE